Automake

2019年11月19日 阅读数:127
这篇文章主要向大家介绍Automake,主要内容包括基础应用、实用技巧、原理机制等方面,希望对大家有所帮助。

Automake是用来根据Makefile.am生成Makefile.in的工具

标准Makefile目标
'make all'
     Build programs, libraries, documentation, etc. (same as 'make').
'make install'
     Install what needs to be installed, copying the files from the
     package's tree to system-wide directories.
'make install-strip'
     Same as 'make install', then strip debugging symbols.  Some users
     like to trade space for useful bug reports...
'make uninstall'
     The opposite of 'make install': erase the installed files.  (This
     needs to be run from the same build tree that was installed.)
'make clean'
     Erase from the build tree the files built by 'make all'.
'make distclean'
     Additionally erase anything './configure' created.
'make check'
     Run the test suite, if any.
'make installcheck'
     Check the installed programs or libraries, if supported.
'make dist'
     Recreate 'PACKAGE-VERSION.tar.gz' from all the source files.

标准目录变量
Directory variable   Default value
-------------------------------------------------------
'prefix'             '/usr/local'
  'exec_prefix'      '${prefix}'
    'bindir'         '${exec_prefix}/bin'
    'libdir'         '${exec_prefix}/lib'
    ...
  'includedir'       '${prefix}/include'
  'datarootdir'      '${prefix}/share'
    'datadir'        '${datarootdir}'
    'mandir'         '${datarootdir}/man'
    'infodir'        '${datarootdir}/info'
    'docdir'         '${datarootdir}/doc/${PACKAGE}'
 
标准配置变量
The GNU Coding Standards also define a set of standard configuration
variables used during the build.  Here are some:

'CC'
     C compiler command
'CFLAGS'
     C compiler flags
'CXX'
     C++ compiler command
'CXXFLAGS'
     C++ compiler flags
'LDFLAGS'
     linker flags
'CPPFLAGS'
     C/C++ preprocessor flags
...

   Here is how one would call 'configure' to force it to use 'gcc-3' as
C compiler, use header files from '~/usr/include' when compiling, and
libraries from '~/usr/lib' when linking.

     ~/amhello-1.0 % ./configure --prefix ~/usr CC=gcc-3 
     CPPFLAGS=-I$HOME/usr/include LDFLAGS=-L$HOME/usr/lib

   Again, a full list of these variables appears in the output of
'./configure --help'.

2.2.5 Overriding Default Configuration Setting with 'config.site'
-----------------------------------------------------------------

When installing several packages using the same setup, it can be
convenient to create a file to capture common settings.  If a file named
'PREFIX/share/config.site' exists, 'configure' will source it at the
beginning of its execution.

   Recall the command from the previous section:

     ~/amhello-1.0 % ./configure --prefix ~/usr CC=gcc-3 
     CPPFLAGS=-I$HOME/usr/include LDFLAGS=-L$HOME/usr/lib

   Assuming we are installing many package in '~/usr', and will always
want to use these definitions of 'CC', 'CPPFLAGS', and 'LDFLAGS', we can
automate this by creating the following '~/usr/share/config.site' file:

     test -z "$CC" && CC=gcc-3
     test -z "$CPPFLAGS" && CPPFLAGS=-I$HOME/usr/include
     test -z "$LDFLAGS" && LDFLAGS=-L$HOME/usr/lib

   Now, any time a 'configure' script is using the '~/usr' prefix, it
will execute the above 'config.site' and define these three variables.

     ~/amhello-1.0 % ./configure --prefix ~/usr
     configure: loading site script /home/adl/usr/share/config.site
     ...

   *Note Setting Site Defaults: (autoconf)Site Defaults, for more
information about this feature.

2.2.6 Parallel Build Trees (a.k.a. VPATH Builds)
------------------------------------------------

The GNU Build System distinguishes two trees: the source tree, and the
build tree.

   The source tree is rooted in the directory containing 'configure'.
It contains all the sources files (those that are distributed), and may
be arranged using several subdirectories.

   The build tree is rooted in the directory in which 'configure' was
run, and is populated with all object files, programs, libraries, and
other derived files built from the sources (and hence not distributed).
The build tree usually has the same subdirectory layout as the source
tree; its subdirectories are created automatically by the build system.

   If 'configure' is executed in its own directory, the source and build
trees are combined: derived files are constructed in the same
directories as their sources.  This was the case in our first
installation example (*note Basic Installation::).

   A common request from users is that they want to confine all derived
files to a single directory, to keep their source directories
uncluttered.  Here is how we could run 'configure' to build everything
in a subdirectory called 'build/'.

     ~ % tar zxf ~/amhello-1.0.tar.gz
     ~ % cd amhello-1.0
     ~/amhello-1.0 % mkdir build && cd build
     ~/amhello-1.0/build % ../configure
     ...
     ~/amhello-1.0/build % make
     ...

   These setups, where source and build trees are different, are often
called "parallel builds" or "VPATH builds".  The expression _parallel
build_ is misleading: the word _parallel_ is a reference to the way the
build tree shadows the source tree, it is not about some concurrency in
the way build commands are run.  For this reason we refer to such setups
using the name _VPATH builds_ in the following.  _VPATH_ is the name of
the 'make' feature used by the 'Makefile's to allow these builds (*note
'VPATH' Search Path for All Prerequisites: (make)General Search.).

   VPATH builds have other interesting uses.  One is to build the same
sources with multiple configurations.  For instance:

     ~ % tar zxf ~/amhello-1.0.tar.gz
     ~ % cd amhello-1.0
     ~/amhello-1.0 % mkdir debug optim && cd debug
     ~/amhello-1.0/debug % ../configure CFLAGS='-g -O0'
     ...
     ~/amhello-1.0/debug % make
     ...
     ~/amhello-1.0/debug % cd ../optim
     ~/amhello-1.0/optim % ../configure CFLAGS='-O3 -fomit-frame-pointer'
     ...
     ~/amhello-1.0/optim % make
     ...

   With network file systems, a similar approach can be used to build
the same sources on different machines.  For instance, suppose that the
sources are installed on a directory shared by two hosts: 'HOST1' and
'HOST2', which may be different platforms.

     ~ % cd /nfs/src
     /nfs/src % tar zxf ~/amhello-1.0.tar.gz

   On the first host, you could create a local build directory:
     [HOST1] ~ % mkdir /tmp/amh && cd /tmp/amh
     [HOST1] /tmp/amh % /nfs/src/amhello-1.0/configure
     ...
     [HOST1] /tmp/amh % make && sudo make install
     ...

(Here we assume that the installer has configured 'sudo' so it can
execute 'make install' with root privileges; it is more convenient than
using 'su' like in *note Basic Installation::).

   On the second host, you would do exactly the same, possibly at the
same time:
     [HOST2] ~ % mkdir /tmp/amh && cd /tmp/amh
     [HOST2] /tmp/amh % /nfs/src/amhello-1.0/configure
     ...
     [HOST2] /tmp/amh % make && sudo make install
     ...

   In this scenario, nothing forbids the '/nfs/src/amhello-1.0'
directory from being read-only.  In fact VPATH builds are also a means
of building packages from a read-only medium such as a CD-ROM. (The FSF
used to sell CD-ROM with unpacked source code, before the GNU project
grew so big.)

2.2.7 Two-Part Installation
---------------------------

In our last example (*note VPATH Builds::), a source tree was shared by
two hosts, but compilation and installation were done separately on each
host.

   The GNU Build System also supports networked setups where part of the
installed files should be shared amongst multiple hosts.  It does so by
distinguishing architecture-dependent files from
architecture-independent files, and providing two 'Makefile' targets to
install each of these classes of files.

   These targets are 'install-exec' for architecture-dependent files and
'install-data' for architecture-independent files.  The command we used
up to now, 'make install', can be thought of as a shorthand for 'make
install-exec install-data'.

   From the GNU Build System point of view, the distinction between
architecture-dependent files and architecture-independent files is based
exclusively on the directory variable used to specify their installation
destination.  In the list of directory variables we provided earlier
(*note Standard Directory Variables::), all the variables based on
EXEC-PREFIX designate architecture-dependent directories whose files
will be installed by 'make install-exec'.  The others designate
architecture-independent directories and will serve files installed by
'make install-data'.  *Note The Two Parts of Install::, for more
details.

   Here is how we could revisit our two-host installation example,
assuming that (1) we want to install the package directly in '/usr', and
(2) the directory '/usr/share' is shared by the two hosts.

   On the first host we would run
     [HOST1] ~ % mkdir /tmp/amh && cd /tmp/amh
     [HOST1] /tmp/amh % /nfs/src/amhello-1.0/configure --prefix /usr
     ...
     [HOST1] /tmp/amh % make && sudo make install
     ...

   On the second host, however, we need only install the
architecture-specific files.
     [HOST2] ~ % mkdir /tmp/amh && cd /tmp/amh
     [HOST2] /tmp/amh % /nfs/src/amhello-1.0/configure --prefix /usr
     ...
     [HOST2] /tmp/amh % make && sudo make install-exec
     ...

   In packages that have installation checks, it would make sense to run
'make installcheck' (*note Basic Installation::) to verify that the
package works correctly despite the apparent partial installation.

2.2.8 Cross-Compilation
-----------------------

To "cross-compile" is to build on one platform a binary that will run on
another platform.  When speaking of cross-compilation, it is important
to distinguish between the "build platform" on which the compilation is
performed, and the "host platform" on which the resulting executable is
expected to run.  The following 'configure' options are used to specify
each of them:

'--build=BUILD'
     The system on which the package is built.
'--host=HOST'
     The system where built programs and libraries will run.

   When the '--host' is used, 'configure' will search for the
cross-compiling suite for this platform.  Cross-compilation tools
commonly have their target architecture as prefix of their name.  For
instance my cross-compiler for MinGW32 has its binaries called
'i586-mingw32msvc-gcc', 'i586-mingw32msvc-ld', 'i586-mingw32msvc-as',
etc.

   Here is how we could build 'amhello-1.0' for 'i586-mingw32msvc' on a
GNU/Linux PC.

     ~/amhello-1.0 % ./configure --build i686-pc-linux-gnu --host i586-mingw32msvc
     checking for a BSD-compatible install... /usr/bin/install -c
     checking whether build environment is sane... yes
     checking for gawk... gawk
     checking whether make sets $(MAKE)... yes
     checking for i586-mingw32msvc-strip... i586-mingw32msvc-strip
     checking for i586-mingw32msvc-gcc... i586-mingw32msvc-gcc
     checking for C compiler default output file name... a.exe
     checking whether the C compiler works... yes
     checking whether we are cross compiling... yes
     checking for suffix of executables... .exe
     checking for suffix of object files... o
     checking whether we are using the GNU C compiler... yes
     checking whether i586-mingw32msvc-gcc accepts -g... yes
     checking for i586-mingw32msvc-gcc option to accept ANSI C...
     ...
     ~/amhello-1.0 % make
     ...
     ~/amhello-1.0 % cd src; file hello.exe
     hello.exe: MS Windows PE 32-bit Intel 80386 console executable not relocatable

   The '--host' and '--build' options are usually all we need for
cross-compiling.  The only exception is if the package being built is
itself a cross-compiler: we need a third option to specify its target
architecture.

'--target=TARGET'
     When building compiler tools: the system for which the tools will
     create output.

   For instance when installing GCC, the GNU Compiler Collection, we can
use '--target=TARGET' to specify that we want to build GCC as a
cross-compiler for TARGET.  Mixing '--build' and '--target', we can
actually cross-compile a cross-compiler; such a three-way
cross-compilation is known as a "Canadian cross".

   *Note Specifying the System Type: (autoconf)Specifying Names, for
more information about these 'configure' options.

2.2.9 Renaming Programs at Install Time
---------------------------------------

The GNU Build System provides means to automatically rename executables
and manpages before they are installed (*note Man Pages::).  This is
especially convenient when installing a GNU package on a system that
already has a proprietary implementation you do not want to overwrite.
For instance, you may want to install GNU 'tar' as 'gtar' so you can
distinguish it from your vendor's 'tar'.

   This can be done using one of these three 'configure' options.

'--program-prefix=PREFIX'
     Prepend PREFIX to installed program names.
'--program-suffix=SUFFIX'
     Append SUFFIX to installed program names.
'--program-transform-name=PROGRAM'
     Run 'sed PROGRAM' on installed program names.

   The following commands would install 'hello' as
'/usr/local/bin/test-hello', for instance.

     ~/amhello-1.0 % ./configure --program-prefix test-
     ...
     ~/amhello-1.0 % make
     ...
     ~/amhello-1.0 % sudo make install
     ...

2.2.10 Building Binary Packages Using DESTDIR
---------------------------------------------

The GNU Build System's 'make install' and 'make uninstall' interface
does not exactly fit the needs of a system administrator who has to
deploy and upgrade packages on lots of hosts.  In other words, the GNU
Build System does not replace a package manager.

   Such package managers usually need to know which files have been
installed by a package, so a mere 'make install' is inappropriate.

   The 'DESTDIR' variable can be used to perform a staged installation.
The package should be configured as if it was going to be installed in
its final location (e.g., '--prefix /usr'), but when running 'make
install', the 'DESTDIR' should be set to the absolute name of a
directory into which the installation will be diverted.  From this
directory it is easy to review which files are being installed where,
and finally copy them to their final location by some means.

   For instance here is how we could create a binary package containing
a snapshot of all the files to be installed.

     ~/amhello-1.0 % ./configure --prefix /usr
     ...
     ~/amhello-1.0 % make
     ...
     ~/amhello-1.0 % make DESTDIR=$HOME/inst install
     ...
     ~/amhello-1.0 % cd ~/inst
     ~/inst % find . -type f -print > ../files.lst
     ~/inst % tar zcvf ~/amhello-1.0-i686.tar.gz `cat ../files.lst`
     ./usr/bin/hello
     ./usr/share/doc/amhello/README

   After this example, 'amhello-1.0-i686.tar.gz' is ready to be
uncompressed in '/' on many hosts.  (Using '`cat ../files.lst`' instead
of '.' as argument for 'tar' avoids entries for each subdirectory in the
archive: we would not like 'tar' to restore the modification time of
'/', '/usr/', etc.)

   Note that when building packages for several architectures, it might
be convenient to use 'make install-data' and 'make install-exec' (*note
Two-Part Install::) to gather architecture-independent files in a single
package.

   *Note Install::, for more information.

2.2.11 Preparing Distributions
------------------------------

We have already mentioned 'make dist'.  This target collects all your
source files and the necessary parts of the build system to create a
tarball named 'PACKAGE-VERSION.tar.gz'.

   Another, more useful command is 'make distcheck'.  The 'distcheck'
target constructs 'PACKAGE-VERSION.tar.gz' just as well as 'dist', but
it additionally ensures most of the use cases presented so far work:

   * It attempts a full compilation of the package (*note Basic
     Installation::), unpacking the newly constructed tarball, running
     'make', 'make check', 'make install', as well as 'make
     installcheck', and even 'make dist',
   * it tests VPATH builds with read-only source tree (*note VPATH
     Builds::),
   * it makes sure 'make clean', 'make distclean', and 'make uninstall'
     do not omit any file (*note Standard Targets::),
   * and it checks that 'DESTDIR' installations work (*note DESTDIR::).

   All of these actions are performed in a temporary subdirectory, so
that no root privileges are required.

   Releasing a package that fails 'make distcheck' means that one of the
scenarios we presented will not work and some users will be
disappointed.  Therefore it is a good practice to release a package only
after a successful 'make distcheck'.  This of course does not imply that
the package will be flawless, but at least it will prevent some of the
embarrassing errors you may find in packages released by people who have
never heard about 'distcheck' (like 'DESTDIR' not working because of a
typo, or a distributed file being erased by 'make clean', or even
'VPATH' builds not working).

   *Note Creating amhello::, to recreate 'amhello-1.0.tar.gz' using
'make distcheck'.  *Note Checking the Distribution::, for more
information about 'distcheck'.

2.2.12 Automatic Dependency Tracking
------------------------------------

Dependency tracking is performed as a side-effect of compilation.  Each
time the build system compiles a source file, it computes its list of
dependencies (in C these are the header files included by the source
being compiled).  Later, any time 'make' is run and a dependency appears
to have changed, the dependent files will be rebuilt.

   Automake generates code for automatic dependency tracking by default,
unless the developer chooses to override it; for more information, *note
Dependencies::.

   When 'configure' is executed, you can see it probing each compiler
for the dependency mechanism it supports (several mechanisms can be
used):

     ~/amhello-1.0 % ./configure --prefix /usr
     ...
     checking dependency style of gcc... gcc3
     ...

   Because dependencies are only computed as a side-effect of the
compilation, no dependency information exists the first time a package
is built.  This is OK because all the files need to be built anyway:
'make' does not have to decide which files need to be rebuilt.  In fact,
dependency tracking is completely useless for one-time builds and there
is a 'configure' option to disable this:

'--disable-dependency-tracking'
     Speed up one-time builds.

   Some compilers do not offer any practical way to derive the list of
dependencies as a side-effect of the compilation, requiring a separate
run (maybe of another tool) to compute these dependencies.  The
performance penalty implied by these methods is important enough to
disable them by default.  The option '--enable-dependency-tracking' must
be passed to 'configure' to activate them.

'--enable-dependency-tracking'
     Do not reject slow dependency extractors.

   *Note Dependency Tracking Evolution: (automake-history)Dependency
Tracking Evolution, for some discussion about the different dependency
tracking schemes used by Automake over the years.

2.2.13 Nested Packages
----------------------

Although nesting packages isn't something we would recommend to someone
who is discovering the Autotools, it is a nice feature worthy of mention
in this small advertising tour.

   Autoconfiscated packages (that means packages whose build system have
been created by Autoconf and friends) can be nested to arbitrary depth.

   A typical setup is that package A will distribute one of the
libraries it needs in a subdirectory.  This library B is a complete
package with its own GNU Build System.  The 'configure' script of A will
run the 'configure' script of B as part of its execution, building and
installing A will also build and install B. Generating a distribution
for A will also include B.

   It is possible to gather several packages like this.  GCC is a heavy
user of this feature.  This gives installers a single package to
configure, build and install, while it allows developers to work on
subpackages independently.

   When configuring nested packages, the 'configure' options given to
the top-level 'configure' are passed recursively to nested 'configure's.
A package that does not understand an option will ignore it, assuming it
is meaningful to some other package.

   The command 'configure --help=recursive' can be used to display the
options supported by all the included packages.

   *Note Subpackages::, for an example setup.

2.3 How Autotools Help
======================

There are several reasons why you may not want to implement the GNU
Build System yourself (read: write a 'configure' script and 'Makefile's
yourself).

   * As we have seen, the GNU Build System has a lot of features (*note
     Use Cases::).  Some users may expect features you have not
     implemented because you did not need them.
   * Implementing these features portably is difficult and exhausting.
     Think of writing portable shell scripts, and portable 'Makefile's,
     for systems you may not have handy.  *Note Portable Shell
     Programming: (autoconf)Portable Shell, to convince yourself.
   * You will have to upgrade your setup to follow changes to the GNU
     Coding Standards.

   The GNU Autotools take all this burden off your back and provide:

   * Tools to create a portable, complete, and self-contained GNU Build
     System, from simple instructions.  _Self-contained_ meaning the
     resulting build system does not require the GNU Autotools.
   * A central place where fixes and improvements are made: a bug-fix
     for a portability issue will benefit every package.

   Yet there also exist reasons why you may want NOT to use the
Autotools...  For instance you may be already using (or used to) another
incompatible build system.  Autotools will only be useful if you do
accept the concepts of the GNU Build System.  People who have their own
idea of how a build system should work will feel frustrated by the
Autotools.


3 General ideas
***************

The following sections cover a few basic ideas that will help you
understand how Automake works.

3.1 General Operation
=====================

Automake works by reading a 'Makefile.am' and generating a
'Makefile.in'.  Certain variables and rules defined in the 'Makefile.am'
instruct Automake to generate more specialized code; for instance, a
'bin_PROGRAMS' variable definition will cause rules for compiling and
linking programs to be generated.

   The variable definitions and rules in the 'Makefile.am' are copied
mostly verbatim into the generated file, with all variable definitions
preceding all rules.  This allows you to add almost arbitrary code into
the generated 'Makefile.in'.  For instance, the Automake distribution
includes a non-standard rule for the 'git-dist' target, which the
Automake maintainer uses to make distributions from the source control
system.

   Note that most GNU make extensions are not recognized by Automake.
Using such extensions in a 'Makefile.am' will lead to errors or
confusing behavior.

   A special exception is that the GNU make append operator, '+=', is
supported.  This operator appends its right hand argument to the
variable specified on the left.  Automake will translate the operator
into an ordinary '=' operator; '+=' will thus work with any make
program.

   Automake tries to keep comments grouped with any adjoining rules or
variable definitions.

   Generally, Automake is not particularly smart in the parsing of
unusual Makefile constructs, so you're advised to avoid fancy constructs
or "creative" use of whitespaces.  For example, <TAB> characters cannot
be used between a target name and the following "':'" character, and
variable assignments shouldn't be indented with <TAB> characters.  Also,
using more complex macro in target names can cause trouble:

     % cat Makefile.am
     $(FOO:=x): bar
     % automake
     Makefile.am:1: bad characters in variable name '$(FOO'
     Makefile.am:1: ':='-style assignments are not portable

   A rule defined in 'Makefile.am' generally overrides any such rule of
a similar name that would be automatically generated by 'automake'.
Although this is a supported feature, it is generally best to avoid
making use of it, as sometimes the generated rules are very particular.

   Similarly, a variable defined in 'Makefile.am' or 'AC_SUBST'ed from
'configure.ac' will override any definition of the variable that
'automake' would ordinarily create.  This feature is more often useful
than the ability to override a rule.  Be warned that many of the
variables generated by 'automake' are considered to be for internal use
only, and their names might change in future releases.

   When examining a variable definition, Automake will recursively
examine variables referenced in the definition.  For example, if
Automake is looking at the content of 'foo_SOURCES' in this snippet

     xs = a.c b.c
     foo_SOURCES = c.c $(xs)

   it would use the files 'a.c', 'b.c', and 'c.c' as the contents of
'foo_SOURCES'.

   Automake also allows a form of comment that is _not_ copied into the
output; all lines beginning with '##' (leading spaces allowed) are
completely ignored by Automake.

   It is customary to make the first line of 'Makefile.am' read:

     ## Process this file with automake to produce Makefile.in

3.2 Strictness
==============

While Automake is intended to be used by maintainers of GNU packages, it
does make some effort to accommodate those who wish to use it, but do
not want to use all the GNU conventions.

   To this end, Automake supports three levels of "strictness"--the
strictness indicating how stringently Automake should check standards
conformance.

   The valid strictness levels are:

'foreign'
     Automake will check for only those things that are absolutely
     required for proper operations.  For instance, whereas GNU
     standards dictate the existence of a 'NEWS' file, it will not be
     required in this mode.  This strictness will also turn off some
     warnings by default (among them, portability warnings).  The name
     comes from the fact that Automake is intended to be used for GNU
     programs; these relaxed rules are not the standard mode of
     operation.

'gnu'
     Automake will check--as much as possible--for compliance to the GNU
     standards for packages.  This is the default.

'gnits'
     Automake will check for compliance to the as-yet-unwritten "Gnits
     standards".  These are based on the GNU standards, but are even
     more detailed.  Unless you are a Gnits standards contributor, it is
     recommended that you avoid this option until such time as the Gnits
     standard is actually published (which may never happen).

   *Note Gnits::, for more information on the precise implications of
the strictness level.

3.3 The Uniform Naming Scheme
=============================

Automake variables generally follow a "uniform naming scheme" that makes
it easy to decide how programs (and other derived objects) are built,
and how they are installed.  This scheme also supports 'configure' time
determination of what should be built.

   At 'make' time, certain variables are used to determine which objects
are to be built.  The variable names are made of several pieces that are
concatenated together.

   The piece that tells 'automake' what is being built is commonly
called the "primary".  For instance, the primary 'PROGRAMS' holds a list
of programs that are to be compiled and linked.

   A different set of names is used to decide where the built objects
should be installed.  These names are prefixes to the primary, and they
indicate which standard directory should be used as the installation
directory.  The standard directory names are given in the GNU standards
(*note (standards)Directory Variables::).  Automake extends this list
with 'pkgdatadir', 'pkgincludedir', 'pkglibdir', and 'pkglibexecdir';
these are the same as the non-'pkg' versions, but with '$(PACKAGE)'
appended.  For instance, 'pkglibdir' is defined as
'$(libdir)/$(PACKAGE)'.

   For each primary, there is one additional variable named by
prepending 'EXTRA_' to the primary name.  This variable is used to list
objects that may or may not be built, depending on what 'configure'
decides.  This variable is required because Automake must statically
know the entire list of objects that may be built in order to generate a
'Makefile.in' that will work in all cases.

   For instance, 'cpio' decides at configure time which programs should
be built.  Some of the programs are installed in 'bindir', and some are
installed in 'sbindir':

     EXTRA_PROGRAMS = mt rmt
     bin_PROGRAMS = cpio pax
     sbin_PROGRAMS = $(MORE_PROGRAMS)

   Defining a primary without a prefix as a variable, e.g., 'PROGRAMS',
is an error.

   Note that the common 'dir' suffix is left off when constructing the
variable names; thus one writes 'bin_PROGRAMS' and not
'bindir_PROGRAMS'.

   Not every sort of object can be installed in every directory.
Automake will flag those attempts it finds in error (but see below how
to override the check if you really need to).  Automake will also
diagnose obvious misspellings in directory names.

   Sometimes the standard directories--even as augmented by
Automake--are not enough.  In particular it is sometimes useful, for
clarity, to install objects in a subdirectory of some predefined
directory.  To this end, Automake allows you to extend the list of
possible installation directories.  A given prefix (e.g., 'zar') is
valid if a variable of the same name with 'dir' appended is defined
(e.g., 'zardir').

   For instance, the following snippet will install 'file.xml' into
'$(datadir)/xml'.

     xmldir = $(datadir)/xml
     xml_DATA = file.xml

   This feature can also be used to override the sanity checks Automake
performs to diagnose suspicious directory/primary couples (in the
unlikely case these checks are undesirable, and you really know what
you're doing).  For example, Automake would error out on this input:

     # Forbidden directory combinations, automake will error out on this.
     pkglib_PROGRAMS = foo
     doc_LIBRARIES = libquux.a

but it will succeed with this:

     # Work around forbidden directory combinations.  Do not use this
     # without a very good reason!
     my_execbindir = $(pkglibdir)
     my_doclibdir = $(docdir)
     my_execbin_PROGRAMS = foo
     my_doclib_LIBRARIES = libquux.a

   The 'exec' substring of the 'my_execbindir' variable lets the files
be installed at the right time (*note The Two Parts of Install::).

   The special prefix 'noinst_' indicates that the objects in question
should be built but not installed at all.  This is usually used for
objects required to build the rest of your package, for instance static
libraries (*note A Library::), or helper scripts.

   The special prefix 'check_' indicates that the objects in question
should not be built until the 'make check' command is run.  Those
objects are not installed either.

   The current primary names are 'PROGRAMS', 'LIBRARIES', 'LTLIBRARIES',
'LISP', 'PYTHON', 'JAVA', 'SCRIPTS', 'DATA', 'HEADERS', 'MANS', and
'TEXINFOS'.

   Some primaries also allow additional prefixes that control other
aspects of 'automake''s behavior.  The currently defined prefixes are
'dist_', 'nodist_', 'nobase_', and 'notrans_'.  These prefixes are
explained later (*note Program and Library Variables::) (*note Man
Pages::).

3.4 Staying below the command line length limit
===============================================

Traditionally, most unix-like systems have a length limitation for the
command line arguments and environment contents when creating new
processes (see for example
<http://www.in-ulm.de/~mascheck/various/argmax/> for an overview on this
issue), which of course also applies to commands spawned by 'make'.
POSIX requires this limit to be at least 4096 bytes, and most modern
systems have quite high limits (or are unlimited).

   In order to create portable Makefiles that do not trip over these
limits, it is necessary to keep the length of file lists bounded.
Unfortunately, it is not possible to do so fully transparently within
Automake, so your help may be needed.  Typically, you can split long
file lists manually and use different installation directory names for
each list.  For example,

     data_DATA = file1 ... fileN fileN+1 ... file2N

may also be written as

     data_DATA = file1 ... fileN
     data2dir = $(datadir)
     data2_DATA = fileN+1 ... file2N

and will cause Automake to treat the two lists separately during 'make
install'.  See *note The Two Parts of Install:: for choosing directory
names that will keep the ordering of the two parts of installation Note
that 'make dist' may still only work on a host with a higher length
limit in this example.

   Automake itself employs a couple of strategies to avoid long command
lines.  For example, when '${srcdir}/' is prepended to file names, as
can happen with above '$(data_DATA)' lists, it limits the amount of
arguments passed to external commands.

   Unfortunately, some system's 'make' commands may prepend 'VPATH'
prefixes like '${srcdir}/' to file names from the source tree
automatically (*note Automatic Rule Rewriting: (autoconf)Automatic Rule
Rewriting.).  In this case, the user may have to switch to use GNU Make,
or refrain from using VPATH builds, in order to stay below the length
limit.

   For libraries and programs built from many sources, convenience
archives may be used as intermediates in order to limit the object list
length (*note Libtool Convenience Libraries::).

3.5 How derived variables are named
===================================

Sometimes a Makefile variable name is derived from some text the
maintainer supplies.  For instance, a program name listed in '_PROGRAMS'
is rewritten into the name of a '_SOURCES' variable.  In cases like
this, Automake canonicalizes the text, so that program names and the
like do not have to follow Makefile variable naming rules.  All
characters in the name except for letters, numbers, the strudel (@), and
the underscore are turned into underscores when making variable
references.

   For example, if your program is named 'sniff-glue', the derived
variable name would be 'sniff_glue_SOURCES', not 'sniff-glue_SOURCES'.
Similarly the sources for a library named 'libmumble++.a' should be
listed in the 'libmumble___a_SOURCES' variable.

   The strudel is an addition, to make the use of Autoconf substitutions
in variable names less obfuscating.

3.6 Variables reserved for the user
===================================

Some 'Makefile' variables are reserved by the GNU Coding Standards for
the use of the "user"--the person building the package.  For instance,
'CFLAGS' is one such variable.

   Sometimes package developers are tempted to set user variables such
as 'CFLAGS' because it appears to make their job easier.  However, the
package itself should never set a user variable, particularly not to
include switches that are required for proper compilation of the
package.  Since these variables are documented as being for the package
builder, that person rightfully expects to be able to override any of
these variables at build time.

   To get around this problem, Automake introduces an automake-specific
shadow variable for each user flag variable.  (Shadow variables are not
introduced for variables like 'CC', where they would make no sense.)
The shadow variable is named by prepending 'AM_' to the user variable's
name.  For instance, the shadow variable for 'YFLAGS' is 'AM_YFLAGS'.
The package maintainer--that is, the author(s) of the 'Makefile.am' and
'configure.ac' files--may adjust these shadow variables however
necessary.

   *Note Flag Variables Ordering::, for more discussion about these
variables and how they interact with per-target variables.

3.7 Programs automake might require
===================================

Automake sometimes requires helper programs so that the generated
'Makefile' can do its work properly.  There are a fairly large number of
them, and we list them here.

   Although all of these files are distributed and installed with
Automake, a couple of them are maintained separately.  The Automake
copies are updated before each release, but we mention the original
source in case you need more recent versions.

'ar-lib'
     This is a wrapper primarily for the Microsoft lib archiver, to make
     it more POSIX-like.

'compile'
     This is a wrapper for compilers that do not accept options '-c' and
     '-o' at the same time.  It is only used when absolutely required.
     Such compilers are rare, with the Microsoft C/C++ Compiler as the
     most notable exception.  This wrapper also makes the following
     common options available for that compiler, while performing file
     name translation where needed: '-I', '-L', '-l', '-Wl,' and
     '-Xlinker'.

'config.guess'
'config.sub'
     These two programs compute the canonical triplets for the given
     build, host, or target architecture.  These programs are updated
     regularly to support new architectures and fix probes broken by
     changes in new kernel versions.  Each new release of Automake comes
     with up-to-date copies of these programs.  If your copy of Automake
     is getting old, you are encouraged to fetch the latest versions of
     these files from <http://savannah.gnu.org/git/?group=config> before
     making a release.

'depcomp'
     This program understands how to run a compiler so that it will
     generate not only the desired output but also dependency
     information that is then used by the automatic dependency tracking
     feature (*note Dependencies::).

'install-sh'
     This is a replacement for the 'install' program that works on
     platforms where 'install' is unavailable or unusable.

'mdate-sh'
     This script is used to generate a 'version.texi' file.  It examines
     a file and prints some date information about it.

'missing'
     This wraps a number of programs that are typically only required by
     maintainers.  If the program in question doesn't exist, or seems to
     old, 'missing' will print an informative warning before failing
     out, to provide the user with more context and information.

'mkinstalldirs'
     This script used to be a wrapper around 'mkdir -p', which is not
     portable.  Now we prefer to use 'install-sh -d' when 'configure'
     finds that 'mkdir -p' does not work, this makes one less script to
     distribute.

     For backward compatibility 'mkinstalldirs' is still used and
     distributed when 'automake' finds it in a package.  But it is no
     longer installed automatically, and it should be safe to remove it.

'py-compile'
     This is used to byte-compile Python scripts.

'test-driver'
     This implements the default test driver offered by the parallel
     testsuite harness.

'texinfo.tex'
     Not a program, this file is required for 'make dvi', 'make ps' and
     'make pdf' to work when Texinfo sources are in the package.  The
     latest version can be downloaded from
     <http://www.gnu.org/software/texinfo/>.

'ylwrap'
     This program wraps 'lex' and 'yacc' to rename their output files.
     It also ensures that, for instance, multiple 'yacc' instances can
     be invoked in a single directory in parallel.

4 Some example packages
***********************

This section contains two small examples.

   The first example (*note Complete::) assumes you have an existing
project already using Autoconf, with handcrafted 'Makefile's, and that
you want to convert it to using Automake.  If you are discovering both
tools, it is probably better that you look at the Hello World example
presented earlier (*note Hello World::).

   The second example (*note true::) shows how two programs can be built
from the same file, using different compilation parameters.  It contains
some technical digressions that are probably best skipped on first read.

4.1 A simple example, start to finish
=====================================

Let's suppose you just finished writing 'zardoz', a program to make your
head float from vortex to vortex.  You've been using Autoconf to provide
a portability framework, but your 'Makefile.in's have been ad-hoc.  You
want to make them bulletproof, so you turn to Automake.

   The first step is to update your 'configure.ac' to include the
commands that 'automake' needs.  The way to do this is to add an
'AM_INIT_AUTOMAKE' call just after 'AC_INIT':

     AC_INIT([zardoz], [1.0])
     AM_INIT_AUTOMAKE
     ...

   Since your program doesn't have any complicating factors (e.g., it
doesn't use 'gettext', it doesn't want to build a shared library),
you're done with this part.  That was easy!

   Now you must regenerate 'configure'.  But to do that, you'll need to
tell 'autoconf' how to find the new macro you've used.  The easiest way
to do this is to use the 'aclocal' program to generate your 'aclocal.m4'
for you.  But wait... maybe you already have an 'aclocal.m4', because
you had to write some hairy macros for your program.  The 'aclocal'
program lets you put your own macros into 'acinclude.m4', so simply
rename and then run:

     mv aclocal.m4 acinclude.m4
     aclocal
     autoconf

   Now it is time to write your 'Makefile.am' for 'zardoz'.  Since
'zardoz' is a user program, you want to install it where the rest of the
user programs go: 'bindir'.  Additionally, 'zardoz' has some Texinfo
documentation.  Your 'configure.ac' script uses 'AC_REPLACE_FUNCS', so
you need to link against '$(LIBOBJS)'.  So here's what you'd write:

     bin_PROGRAMS = zardoz
     zardoz_SOURCES = main.c head.c float.c vortex9.c gun.c
     zardoz_LDADD = $(LIBOBJS)

     info_TEXINFOS = zardoz.texi

   Now you can run 'automake --add-missing' to generate your
'Makefile.in' and grab any auxiliary files you might need, and you're
done!

4.2 Building true and false
===========================

Here is another, trickier example.  It shows how to generate two
programs ('true' and 'false') from the same source file ('true.c').  The
difficult part is that each compilation of 'true.c' requires different
'cpp' flags.

     bin_PROGRAMS = true false
     false_SOURCES =
     false_LDADD = false.o

     true.o: true.c
             $(COMPILE) -DEXIT_CODE=0 -c true.c

     false.o: true.c
             $(COMPILE) -DEXIT_CODE=1 -o false.o -c true.c

   Note that there is no 'true_SOURCES' definition.  Automake will
implicitly assume that there is a source file named 'true.c' (*note
Default _SOURCES::), and define rules to compile 'true.o' and link
'true'.  The 'true.o: true.c' rule supplied by the above 'Makefile.am',
will override the Automake generated rule to build 'true.o'.

   'false_SOURCES' is defined to be empty--that way no implicit value is
substituted.  Because we have not listed the source of 'false', we have
to tell Automake how to link the program.  This is the purpose of the
'false_LDADD' line.  A 'false_DEPENDENCIES' variable, holding the
dependencies of the 'false' target will be automatically generated by
Automake from the content of 'false_LDADD'.

   The above rules won't work if your compiler doesn't accept both '-c'
and '-o'.  The simplest fix for this is to introduce a bogus dependency
(to avoid problems with a parallel 'make'):

     true.o: true.c false.o
             $(COMPILE) -DEXIT_CODE=0 -c true.c

     false.o: true.c
             $(COMPILE) -DEXIT_CODE=1 -c true.c && mv true.o false.o

   As it turns out, there is also a much easier way to do this same
task.  Some of the above technique is useful enough that we've kept the
example in the manual.  However if you were to build 'true' and 'false'
in real life, you would probably use per-program compilation flags, like
so:

     bin_PROGRAMS = false true

     false_SOURCES = true.c
     false_CPPFLAGS = -DEXIT_CODE=1

     true_SOURCES = true.c
     true_CPPFLAGS = -DEXIT_CODE=0

   In this case Automake will cause 'true.c' to be compiled twice, with
different flags.  In this instance, the names of the object files would
be chosen by automake; they would be 'false-true.o' and 'true-true.o'.
(The name of the object files rarely matters.)

5 Creating a 'Makefile.in'
**************************

To create all the 'Makefile.in's for a package, run the 'automake'
program in the top level directory, with no arguments.  'automake' will
automatically find each appropriate 'Makefile.am' (by scanning
'configure.ac'; *note configure::) and generate the corresponding
'Makefile.in'.  Note that 'automake' has a rather simplistic view of
what constitutes a package; it assumes that a package has only one
'configure.ac', at the top.  If your package has multiple
'configure.ac's, then you must run 'automake' in each directory holding
a 'configure.ac'.  (Alternatively, you may rely on Autoconf's
'autoreconf', which is able to recurse your package tree and run
'automake' where appropriate.)

   You can optionally give 'automake' an argument; '.am' is appended to
the argument and the result is used as the name of the input file.  This
feature is generally only used to automatically rebuild an out-of-date
'Makefile.in'.  Note that 'automake' must always be run from the topmost
directory of a project, even if being used to regenerate the
'Makefile.in' in some subdirectory.  This is necessary because
'automake' must scan 'configure.ac', and because 'automake' uses the
knowledge that a 'Makefile.in' is in a subdirectory to change its
behavior in some cases.

   Automake will run 'autoconf' to scan 'configure.ac' and its
dependencies (i.e., 'aclocal.m4' and any included file), therefore
'autoconf' must be in your 'PATH'.  If there is an 'AUTOCONF' variable
in your environment it will be used instead of 'autoconf', this allows
you to select a particular version of Autoconf.  By the way, don't
misunderstand this paragraph: 'automake' runs 'autoconf' to *scan* your
'configure.ac', this won't build 'configure' and you still have to run
'autoconf' yourself for this purpose.

   'automake' accepts the following options:

'-a'
'--add-missing'
     Automake requires certain common files to exist in certain
     situations; for instance, 'config.guess' is required if
     'configure.ac' invokes 'AC_CANONICAL_HOST'.  Automake is
     distributed with several of these files (*note Auxiliary
     Programs::); this option will cause the missing ones to be
     automatically added to the package, whenever possible.  In general
     if Automake tells you a file is missing, try using this option.  By
     default Automake tries to make a symbolic link pointing to its own
     copy of the missing file; this can be changed with '--copy'.

     Many of the potentially-missing files are common scripts whose
     location may be specified via the 'AC_CONFIG_AUX_DIR' macro.
     Therefore, 'AC_CONFIG_AUX_DIR''s setting affects whether a file is
     considered missing, and where the missing file is added (*note
     Optional::).

     In some strictness modes, additional files are installed, see *note
     Gnits:: for more information.

'--libdir=DIR'
     Look for Automake data files in directory DIR instead of in the
     installation directory.  This is typically used for debugging.

'--print-libdir'
     Print the path of the installation directory containing
     Automake-provided scripts and data files (like e.g., 'texinfo.texi'
     and 'install-sh').

'-c'
'--copy'
     When used with '--add-missing', causes installed files to be
     copied.  The default is to make a symbolic link.

'-f'
'--force-missing'
     When used with '--add-missing', causes standard files to be
     reinstalled even if they already exist in the source tree.  This
     involves removing the file from the source tree before creating the
     new symlink (or, with '--copy', copying the new file).

'--foreign'
     Set the global strictness to 'foreign'.  For more information, see
     *note Strictness::.

'--gnits'
     Set the global strictness to 'gnits'.  For more information, see
     *note Gnits::.

'--gnu'
     Set the global strictness to 'gnu'.  For more information, see
     *note Gnits::.  This is the default strictness.

'--help'
     Print a summary of the command line options and exit.

'-i'
'--ignore-deps'
     This disables the dependency tracking feature in generated
     'Makefile's; see *note Dependencies::.

'--include-deps'
     This enables the dependency tracking feature.  This feature is
     enabled by default.  This option is provided for historical reasons
     only and probably should not be used.

'--no-force'
     Ordinarily 'automake' creates all 'Makefile.in's mentioned in
     'configure.ac'.  This option causes it to only update those
     'Makefile.in's that are out of date with respect to one of their
     dependents.

'-o DIR'
'--output-dir=DIR'
     Put the generated 'Makefile.in' in the directory DIR.  Ordinarily
     each 'Makefile.in' is created in the directory of the corresponding
     'Makefile.am'.  This option is deprecated and will be removed in a
     future release.

'-v'
'--verbose'
     Cause Automake to print information about which files are being
     read or created.

'--version'
     Print the version number of Automake and exit.

'-W CATEGORY'
'--warnings=CATEGORY'
     Output warnings falling in CATEGORY.  CATEGORY can be one of:
     'gnu'
          warnings related to the GNU Coding Standards (*note
          (standards)Top::).
     'obsolete'
          obsolete features or constructions
     'override'
          user redefinitions of Automake rules or variables
     'portability'
          portability issues (e.g., use of 'make' features that are
          known to be not portable)
     'extra-portability'
          extra portability issues related to obscure tools.  One
          example of such a tool is the Microsoft 'lib' archiver.
     'syntax'
          weird syntax, unused variables, typos
     'unsupported'
          unsupported or incomplete features
     'all'
          all the warnings
     'none'
          turn off all the warnings
     'error'
          treat warnings as errors

     A category can be turned off by prefixing its name with 'no-'.  For
     instance, '-Wno-syntax' will hide the warnings about unused
     variables.

     The categories output by default are 'obsolete', 'syntax' and
     'unsupported'.  Additionally, 'gnu' and 'portability' are enabled
     in '--gnu' and '--gnits' strictness.

     Turning off 'portability' will also turn off 'extra-portability',
     and similarly turning on 'extra-portability' will also turn on
     'portability'.  However, turning on 'portability' or turning off
     'extra-portability' will not affect the other category.

     The environment variable 'WARNINGS' can contain a comma separated
     list of categories to enable.  It will be taken into account before
     the command-line switches, this way '-Wnone' will also ignore any
     warning category enabled by 'WARNINGS'.  This variable is also used
     by other tools like 'autoconf'; unknown categories are ignored for
     this reason.

   If the environment variable 'AUTOMAKE_JOBS' contains a positive
number, it is taken as the maximum number of Perl threads to use in
'automake' for generating multiple 'Makefile.in' files concurrently.
This is an experimental feature.

6 Scanning 'configure.ac', using 'aclocal'
******************************************

Automake scans the package's 'configure.ac' to determine certain
information about the package.  Some 'autoconf' macros are required and
some variables must be defined in 'configure.ac'.  Automake will also
use information from 'configure.ac' to further tailor its output.

   Automake also supplies some Autoconf macros to make the maintenance
easier.  These macros can automatically be put into your 'aclocal.m4'
using the 'aclocal' program.

6.1 Configuration requirements
==============================

The one real requirement of Automake is that your 'configure.ac' call
'AM_INIT_AUTOMAKE'.  This macro does several things that are required
for proper Automake operation (*note Macros::).

   Here are the other macros that Automake requires but which are not
run by 'AM_INIT_AUTOMAKE':

'AC_CONFIG_FILES'
'AC_OUTPUT'
     These two macros are usually invoked as follows near the end of
     'configure.ac'.

          ...
          AC_CONFIG_FILES([
            Makefile
            doc/Makefile
            src/Makefile
            src/lib/Makefile
            ...
          ])
          AC_OUTPUT

     Automake uses these to determine which files to create (*note
     Creating Output Files: (autoconf)Output.).  A listed file is
     considered to be an Automake generated 'Makefile' if there exists a
     file with the same name and the '.am' extension appended.
     Typically, 'AC_CONFIG_FILES([foo/Makefile])' will cause Automake to
     generate 'foo/Makefile.in' if 'foo/Makefile.am' exists.

     When using 'AC_CONFIG_FILES' with multiple input files, as in

          AC_CONFIG_FILES([Makefile:top.in:Makefile.in:bot.in])

     'automake' will generate the first '.in' input file for which a
     '.am' file exists.  If no such file exists the output file is not
     considered to be generated by Automake.

     Files created by 'AC_CONFIG_FILES', be they Automake 'Makefile's or
     not, are all removed by 'make distclean'.  Their inputs are
     automatically distributed, unless they are the output of prior
     'AC_CONFIG_FILES' commands.  Finally, rebuild rules are generated
     in the Automake 'Makefile' existing in the subdirectory of the
     output file, if there is one, or in the top-level 'Makefile'
     otherwise.

     The above machinery (cleaning, distributing, and rebuilding) works
     fine if the 'AC_CONFIG_FILES' specifications contain only literals.
     If part of the specification uses shell variables, 'automake' will
     not be able to fulfill this setup, and you will have to complete
     the missing bits by hand.  For instance, on

          file=input
          ...
          AC_CONFIG_FILES([output:$file],, [file=$file])

     'automake' will output rules to clean 'output', and rebuild it.
     However the rebuild rule will not depend on 'input', and this file
     will not be distributed either.  (You must add 'EXTRA_DIST = input'
     to your 'Makefile.am' if 'input' is a source file.)

     Similarly

          file=output
          file2=out:in
          ...
          AC_CONFIG_FILES([$file:input],, [file=$file])
          AC_CONFIG_FILES([$file2],, [file2=$file2])

     will only cause 'input' to be distributed.  No file will be cleaned
     automatically (add 'DISTCLEANFILES = output out' yourself), and no
     rebuild rule will be output.

     Obviously 'automake' cannot guess what value '$file' is going to
     hold later when 'configure' is run, and it cannot use the shell
     variable '$file' in a 'Makefile'.  However, if you make reference
     to '$file' as '${file}' (i.e., in a way that is compatible with
     'make''s syntax) and furthermore use 'AC_SUBST' to ensure that
     '${file}' is meaningful in a 'Makefile', then 'automake' will be
     able to use '${file}' to generate all of these rules.  For
     instance, here is how the Automake package itself generates
     versioned scripts for its test suite:

          AC_SUBST([APIVERSION], ...)
          ...
          AC_CONFIG_FILES(
            [tests/aclocal-${APIVERSION}:tests/aclocal.in],
            [chmod +x tests/aclocal-${APIVERSION}],
            [APIVERSION=$APIVERSION])
          AC_CONFIG_FILES(
            [tests/automake-${APIVERSION}:tests/automake.in],
            [chmod +x tests/automake-${APIVERSION}])

     Here cleaning, distributing, and rebuilding are done automatically,
     because '${APIVERSION}' is known at 'make'-time.

     Note that you should not use shell variables to declare 'Makefile'
     files for which 'automake' must create 'Makefile.in'.  Even
     'AC_SUBST' does not help here, because 'automake' needs to know the
     file name when it runs in order to check whether 'Makefile.am'
     exists.  (In the very hairy case that your setup requires such use
     of variables, you will have to tell Automake which 'Makefile.in's
     to generate on the command-line.)

     It is possible to let 'automake' emit conditional rules for
     'AC_CONFIG_FILES' with the help of 'AM_COND_IF' (*note Optional::).

     To summarize:
        * Use literals for 'Makefile's, and for other files whenever
          possible.
        * Use '$file' (or '${file}' without 'AC_SUBST([file])') for
          files that 'automake' should ignore.
        * Use '${file}' and 'AC_SUBST([file])' for files that 'automake'
          should not ignore.

6.2 Other things Automake recognizes
====================================

Every time Automake is run it calls Autoconf to trace 'configure.ac'.
This way it can recognize the use of certain macros and tailor the
generated 'Makefile.in' appropriately.  Currently recognized macros and
their effects are:

'AC_CANONICAL_BUILD'
'AC_CANONICAL_HOST'
'AC_CANONICAL_TARGET'
     Automake will ensure that 'config.guess' and 'config.sub' exist.
     Also, the 'Makefile' variables 'build_triplet', 'host_triplet' and
     'target_triplet' are introduced.  See *note Getting the Canonical
     System Type: (autoconf)Canonicalizing.

'AC_CONFIG_AUX_DIR'
     Automake will look for various helper scripts, such as
     'install-sh', in the directory named in this macro invocation.
     (The full list of scripts is: 'ar-lib', 'config.guess',
     'config.sub', 'depcomp', 'compile', 'install-sh', 'ltmain.sh',
     'mdate-sh', 'missing', 'mkinstalldirs', 'py-compile',
     'test-driver', 'texinfo.tex', 'ylwrap'.)  Not all scripts are
     always searched for; some scripts will only be sought if the
     generated 'Makefile.in' requires them.

     If 'AC_CONFIG_AUX_DIR' is not given, the scripts are looked for in
     their standard locations.  For 'mdate-sh', 'texinfo.tex', and
     'ylwrap', the standard location is the source directory
     corresponding to the current 'Makefile.am'.  For the rest, the
     standard location is the first one of '.', '..', or '../..'
     (relative to the top source directory) that provides any one of the
     helper scripts.  *Note Finding 'configure' Input: (autoconf)Input.

     Required files from 'AC_CONFIG_AUX_DIR' are automatically
     distributed, even if there is no 'Makefile.am' in this directory.

'AC_CONFIG_LIBOBJ_DIR'
     Automake will require the sources file declared with 'AC_LIBSOURCE'
     (see below) in the directory specified by this macro.

'AC_CONFIG_HEADERS'
     Automake will generate rules to rebuild these headers from the
     corresponding templates (usually, the template for a 'foo.h' header
     being 'foo.h.in').  Older versions of Automake required the use of
     'AM_CONFIG_HEADER'; this is no longer the case, and that macro has
     indeed been removed.

     As with 'AC_CONFIG_FILES' (*note Requirements::), parts of the
     specification using shell variables will be ignored as far as
     cleaning, distributing, and rebuilding is concerned.

'AC_CONFIG_LINKS'
     Automake will generate rules to remove 'configure' generated links
     on 'make distclean' and to distribute named source files as part of
     'make dist'.

     As for 'AC_CONFIG_FILES' (*note Requirements::), parts of the
     specification using shell variables will be ignored as far as
     cleaning and distributing is concerned.  (There are no rebuild
     rules for links.)

'AC_LIBOBJ'
'AC_LIBSOURCE'
'AC_LIBSOURCES'
     Automake will automatically distribute any file listed in
     'AC_LIBSOURCE' or 'AC_LIBSOURCES'.

     Note that the 'AC_LIBOBJ' macro calls 'AC_LIBSOURCE'.  So if an
     Autoconf macro is documented to call 'AC_LIBOBJ([file])', then
     'file.c' will be distributed automatically by Automake.  This
     encompasses many macros like 'AC_FUNC_ALLOCA', 'AC_FUNC_MEMCMP',
     'AC_REPLACE_FUNCS', and others.

     By the way, direct assignments to 'LIBOBJS' are no longer
     supported.  You should always use 'AC_LIBOBJ' for this purpose.
     *Note 'AC_LIBOBJ' vs. 'LIBOBJS': (autoconf)AC_LIBOBJ vs LIBOBJS.

'AC_PROG_RANLIB'
     This is required if any libraries are built in the package.  *Note
     Particular Program Checks: (autoconf)Particular Programs.

'AC_PROG_CXX'
     This is required if any C++ source is included.  *Note Particular
     Program Checks: (autoconf)Particular Programs.

'AC_PROG_OBJC'
     This is required if any Objective C source is included.  *Note
     Particular Program Checks: (autoconf)Particular Programs.

'AC_PROG_OBJCXX'
     This is required if any Objective C++ source is included.  *Note
     Particular Program Checks: (autoconf)Particular Programs.

'AC_PROG_F77'
     This is required if any Fortran 77 source is included.  *Note
     Particular Program Checks: (autoconf)Particular Programs.

'AC_F77_LIBRARY_LDFLAGS'
     This is required for programs and shared libraries that are a
     mixture of languages that include Fortran 77 (*note Mixing Fortran
     77 With C and C++::).  *Note Autoconf macros supplied with
     Automake: Macros.

'AC_FC_SRCEXT'
     Automake will add the flags computed by 'AC_FC_SRCEXT' to
     compilation of files with the respective source extension (*note
     Fortran Compiler Characteristics: (autoconf)Fortran Compiler.).

'AC_PROG_FC'
     This is required if any Fortran 90/95 source is included.  This
     macro is distributed with Autoconf version 2.58 and later.  *Note
     Particular Program Checks: (autoconf)Particular Programs.

'AC_PROG_LIBTOOL'
     Automake will turn on processing for 'libtool' (*note Introduction:
     (libtool)Top.).

'AC_PROG_YACC'
     If a Yacc source file is seen, then you must either use this macro
     or define the variable 'YACC' in 'configure.ac'.  The former is
     preferred (*note Particular Program Checks: (autoconf)Particular
     Programs.).

'AC_PROG_LEX'
     If a Lex source file is seen, then this macro must be used.  *Note
     Particular Program Checks: (autoconf)Particular Programs.

'AC_REQUIRE_AUX_FILE'
     For each 'AC_REQUIRE_AUX_FILE([FILE])', 'automake' will ensure that
     'FILE' exists in the aux directory, and will complain otherwise.
     It will also automatically distribute the file.  This macro should
     be used by third-party Autoconf macros that require some supporting
     files in the aux directory specified with 'AC_CONFIG_AUX_DIR'
     above.  *Note Finding 'configure' Input: (autoconf)Input.

'AC_SUBST'
     The first argument is automatically defined as a variable in each
     generated 'Makefile.in', unless 'AM_SUBST_NOTMAKE' is also used for
     this variable.  *Note Setting Output Variables: (autoconf)Setting
     Output Variables.

     For every substituted variable VAR, 'automake' will add a line 'VAR
     = VALUE' to each 'Makefile.in' file.  Many Autoconf macros invoke
     'AC_SUBST' to set output variables this way, e.g., 'AC_PATH_XTRA'
     defines 'X_CFLAGS' and 'X_LIBS'.  Thus, you can access these
     variables as '$(X_CFLAGS)' and '$(X_LIBS)' in any 'Makefile.am' if
     'AC_PATH_XTRA' is called.

'AM_CONDITIONAL'
     This introduces an Automake conditional (*note Conditionals::).

'AM_COND_IF'
     This macro allows 'automake' to detect subsequent access within
     'configure.ac' to a conditional previously introduced with
     'AM_CONDITIONAL', thus enabling conditional 'AC_CONFIG_FILES'
     (*note Usage of Conditionals::).

'AM_GNU_GETTEXT'
     This macro is required for packages that use GNU gettext (*note
     gettext::).  It is distributed with gettext.  If Automake sees this
     macro it ensures that the package meets some of gettext's
     requirements.

'AM_GNU_GETTEXT_INTL_SUBDIR'
     This macro specifies that the 'intl/' subdirectory is to be built,
     even if the 'AM_GNU_GETTEXT' macro was invoked with a first
     argument of 'external'.

'AM_MAINTAINER_MODE([DEFAULT-MODE])'
     This macro adds an '--enable-maintainer-mode' option to
     'configure'.  If this is used, 'automake' will cause
     "maintainer-only" rules to be turned off by default in the
     generated 'Makefile.in's, unless DEFAULT-MODE is 'enable'.  This
     macro defines the 'MAINTAINER_MODE' conditional, which you can use
     in your own 'Makefile.am'.  *Note maintainer-mode::.

'AM_SUBST_NOTMAKE(VAR)'
     Prevent Automake from defining a variable VAR, even if it is
     substituted by 'config.status'.  Normally, Automake defines a
     'make' variable for each 'configure' substitution, i.e., for each
     'AC_SUBST([VAR])'.  This macro prevents that definition from
     Automake.  If 'AC_SUBST' has not been called for this variable,
     then 'AM_SUBST_NOTMAKE' has no effects.  Preventing variable
     definitions may be useful for substitution of multi-line values,
     where 'VAR = @VALUE@' might yield unintended results.

'm4_include'
     Files included by 'configure.ac' using this macro will be detected
     by Automake and automatically distributed.  They will also appear
     as dependencies in 'Makefile' rules.

     'm4_include' is seldom used by 'configure.ac' authors, but can
     appear in 'aclocal.m4' when 'aclocal' detects that some required
     macros come from files local to your package (as opposed to macros
     installed in a system-wide directory, *note aclocal Invocation::).

6.3 Auto-generating aclocal.m4
==============================

Automake includes a number of Autoconf macros that can be used in your
package (*note Macros::); some of them are actually required by Automake
in certain situations.  These macros must be defined in your
'aclocal.m4'; otherwise they will not be seen by 'autoconf'.

   The 'aclocal' program will automatically generate 'aclocal.m4' files
based on the contents of 'configure.ac'.  This provides a convenient way
to get Automake-provided macros, without having to search around.  The
'aclocal' mechanism allows other packages to supply their own macros
(*note Extending aclocal::).  You can also use it to maintain your own
set of custom macros (*note Local Macros::).

   At startup, 'aclocal' scans all the '.m4' files it can find, looking
for macro definitions (*note Macro Search Path::).  Then it scans
'configure.ac'.  Any mention of one of the macros found in the first
step causes that macro, and any macros it in turn requires, to be put
into 'aclocal.m4'.

   _Putting_ the file that contains the macro definition into
'aclocal.m4' is usually done by copying the entire text of this file,
including unused macro definitions as well as both '#' and 'dnl'
comments.  If you want to make a comment that will be completely ignored
by 'aclocal', use '##' as the comment leader.

   When a file selected by 'aclocal' is located in a subdirectory
specified as a relative search path with 'aclocal''s '-I' argument,
'aclocal' assumes the file belongs to the package and uses 'm4_include'
instead of copying it into 'aclocal.m4'.  This makes the package
smaller, eases dependency tracking, and cause the file to be distributed
automatically.  (*Note Local Macros::, for an example.)  Any macro that
is found in a system-wide directory, or via an absolute search path will
be copied.  So use '-I `pwd`/reldir' instead of '-I reldir' whenever
some relative directory should be considered outside the package.

   The contents of 'acinclude.m4', if this file exists, are also
automatically included in 'aclocal.m4'.  We recommend against using
'acinclude.m4' in new packages (*note Local Macros::).

   While computing 'aclocal.m4', 'aclocal' runs 'autom4te' (*note Using
'Autom4te': (autoconf)Using autom4te.) in order to trace the macros that
are really used, and omit from 'aclocal.m4' all macros that are
mentioned but otherwise unexpanded (this can happen when a macro is
called conditionally).  'autom4te' is expected to be in the 'PATH', just
as 'autoconf'.  Its location can be overridden using the 'AUTOM4TE'
environment variable.

6.3.1 aclocal Options
---------------------

'aclocal' accepts the following options:

'--automake-acdir=DIR'
     Look for the automake-provided macro files in DIR instead of in the
     installation directory.  This is typically used for debugging.

'--system-acdir=DIR'
     Look for the system-wide third-party macro files (and the special
     'dirlist' file) in DIR instead of in the installation directory.
     This is typically used for debugging.

'--diff[=COMMAND]'
     Run COMMAND on M4 file that would be installed or overwritten by
     '--install'.  The default COMMAND is 'diff -u'.  This option
     implies '--install' and '--dry-run'.

'--dry-run'
     Do not actually overwrite (or create) 'aclocal.m4' and M4 files
     installed by '--install'.

'--help'
     Print a summary of the command line options and exit.

'-I DIR'
     Add the directory DIR to the list of directories searched for '.m4'
     files.

'--install'
     Install system-wide third-party macros into the first directory
     specified with '-I DIR' instead of copying them in the output file.
     Note that this will happen also if DIR is an absolute path.

     When this option is used, and only when this option is used,
     'aclocal' will also honor '#serial NUMBER' lines that appear in
     macros: an M4 file is ignored if there exists another M4 file with
     the same basename and a greater serial number in the search path
     (*note Serials::).

'--force'
     Always overwrite the output file.  The default is to overwrite the
     output file only when really needed, i.e., when its contents
     changes or if one of its dependencies is younger.

     This option forces the update of 'aclocal.m4' (or the file
     specified with '--output' below) and only this file, it has
     absolutely no influence on files that may need to be installed by
     '--install'.

'--output=FILE'
     Cause the output to be put into FILE instead of 'aclocal.m4'.

'--print-ac-dir'
     Prints the name of the directory that 'aclocal' will search to find
     third-party '.m4' files.  When this option is given, normal
     processing is suppressed.  This option was used _in the past_ by
     third-party packages to determine where to install '.m4' macro
     files, but _this usage is today discouraged_, since it causes
     '$(prefix)' not to be thoroughly honoured (which violates the GNU
     Coding Standards), and a similar semantics can be better obtained
     with the 'ACLOCAL_PATH' environment variable; *note Extending
     aclocal::.

'--verbose'
     Print the names of the files it examines.

'--version'
     Print the version number of Automake and exit.

'-W CATEGORY'
'--warnings=CATEGORY'
     Output warnings falling in CATEGORY.  CATEGORY can be one of:
     'syntax'
          dubious syntactic constructs, underquoted macros, unused
          macros, etc.
     'unsupported'
          unknown macros
     'all'
          all the warnings, this is the default
     'none'
          turn off all the warnings
     'error'
          treat warnings as errors

     All warnings are output by default.

     The environment variable 'WARNINGS' is honored in the same way as
     it is for 'automake' (*note automake Invocation::).

6.3.2 Macro Search Path
-----------------------

By default, 'aclocal' searches for '.m4' files in the following
directories, in this order:

'ACDIR-APIVERSION'
     This is where the '.m4' macros distributed with Automake itself are
     stored.  APIVERSION depends on the Automake release used; for
     example, for Automake 1.11.x, APIVERSION = '1.11'.

'ACDIR'
     This directory is intended for third party '.m4' files, and is
     configured when 'automake' itself is built.  This is
     '@datadir@/aclocal/', which typically expands to
     '${prefix}/share/aclocal/'.  To find the compiled-in value of
     ACDIR, use the '--print-ac-dir' option (*note aclocal Options::).

   As an example, suppose that 'automake-1.11.2' was configured with
'--prefix=/usr/local'.  Then, the search path would be:

  1. '/usr/local/share/aclocal-1.11.2/'
  2. '/usr/local/share/aclocal/'

   The paths for the ACDIR and ACDIR-APIVERSION directories can be
changed respectively through aclocal options '--system-acdir' and
'--automake-acdir' (*note aclocal Options::).  Note however that these
options are only intended for use by the internal Automake test suite,
or for debugging under highly unusual situations; they are not
ordinarily needed by end-users.

   As explained in (*note aclocal Options::), there are several options
that can be used to change or extend this search path.

Modifying the Macro Search Path: '-I DIR'
.........................................

Any extra directories specified using '-I' options (*note aclocal
Options::) are _prepended_ to this search list.  Thus, 'aclocal -I /foo
-I /bar' results in the following search path:

  1. '/foo'
  2. '/bar'
  3. ACDIR-APIVERSION
  4. ACDIR

Modifying the Macro Search Path: 'dirlist'
..........................................

There is a third mechanism for customizing the search path.  If a
'dirlist' file exists in ACDIR, then that file is assumed to contain a
list of directory patterns, one per line.  'aclocal' expands these
patterns to directory names, and adds them to the search list _after_
all other directories.  'dirlist' entries may use shell wildcards such
as '*', '?', or '[...]'.

   For example, suppose 'ACDIR/dirlist' contains the following:

     /test1
     /test2
     /test3*

and that 'aclocal' was called with the '-I /foo -I /bar' options.  Then,
the search path would be

  1. '/foo'
  2. '/bar'
  3. ACDIR-APIVERSION
  4. ACDIR
  5. '/test1'
  6. '/test2'

and all directories with path names starting with '/test3'.

   If the '--system-acdir=DIR' option is used, then 'aclocal' will
search for the 'dirlist' file in DIR; but remember the warnings above
against the use of '--system-acdir'.

   'dirlist' is useful in the following situation: suppose that
'automake' version '1.11.2' is installed with '--prefix=/usr' by the
system vendor.  Thus, the default search directories are

  1. '/usr/share/aclocal-1.11/'
  2. '/usr/share/aclocal/'

   However, suppose further that many packages have been manually
installed on the system, with $prefix=/usr/local, as is typical.  In
that case, many of these "extra" '.m4' files are in
'/usr/local/share/aclocal'.  The only way to force '/usr/bin/aclocal' to
find these "extra" '.m4' files is to always call 'aclocal -I
/usr/local/share/aclocal'.  This is inconvenient.  With 'dirlist', one
may create a file '/usr/share/aclocal/dirlist' containing only the
single line

     /usr/local/share/aclocal

   Now, the "default" search path on the affected system is

  1. '/usr/share/aclocal-1.11/'
  2. '/usr/share/aclocal/'
  3. '/usr/local/share/aclocal/'

   without the need for '-I' options; '-I' options can be reserved for
project-specific needs ('my-source-dir/m4/'), rather than using it to
work around local system-dependent tool installation directories.

   Similarly, 'dirlist' can be handy if you have installed a local copy
of Automake in your account and want 'aclocal' to look for macros
installed at other places on the system.

Modifying the Macro Search Path: 'ACLOCAL_PATH'
...............................................

The fourth and last mechanism to customize the macro search path is also
the simplest.  Any directory included in the colon-separated environment
variable 'ACLOCAL_PATH' is added to the search path and takes precedence
over system directories (including those found via 'dirlist'), with the
exception of the versioned directory ACDIR-APIVERSION (*note Macro
Search Path::).  However, directories passed via '-I' will take
precedence over directories in 'ACLOCAL_PATH'.

   Also note that, if the '--install' option is used, any '.m4' file
containing a required macro that is found in a directory listed in
'ACLOCAL_PATH' will be installed locally.  In this case, serial numbers
in '.m4' are honoured too, *note Serials::.

   Conversely to 'dirlist', 'ACLOCAL_PATH' is useful if you are using a
global copy of Automake and want 'aclocal' to look for macros somewhere
under your home directory.

Planned future incompatibilities
................................

The order in which the directories in the macro search path are
currently looked up is confusing and/or suboptimal in various aspects,
and is probably going to be changed in the future Automake release.  In
particular, directories in 'ACLOCAL_PATH' and 'ACDIR' might end up
taking precedence over 'ACDIR-APIVERSION', and directories in
'ACDIR/dirlist' might end up taking precedence over 'ACDIR'.  _This is a
possible future incompatibility!_

6.3.3 Writing your own aclocal macros
-------------------------------------

The 'aclocal' program doesn't have any built-in knowledge of any macros,
so it is easy to extend it with your own macros.

   This can be used by libraries that want to supply their own Autoconf
macros for use by other programs.  For instance, the 'gettext' library
supplies a macro 'AM_GNU_GETTEXT' that should be used by any package
using 'gettext'.  When the library is installed, it installs this macro
so that 'aclocal' will find it.

   A macro file's name should end in '.m4'.  Such files should be
installed in '$(datadir)/aclocal'.  This is as simple as writing:

     aclocaldir = $(datadir)/aclocal
     aclocal_DATA = mymacro.m4 myothermacro.m4

Please do use '$(datadir)/aclocal', and not something based on the
result of 'aclocal --print-ac-dir' (*note Hard-Coded Install Paths::,
for arguments).  It might also be helpful to suggest to the user to add
the '$(datadir)/aclocal' directory to his 'ACLOCAL_PATH' variable (*note
ACLOCAL_PATH::) so that 'aclocal' will find the '.m4' files installed by
your package automatically.

   A file of macros should be a series of properly quoted 'AC_DEFUN''s
(*note (autoconf)Macro Definitions::).  The 'aclocal' programs also
understands 'AC_REQUIRE' (*note (autoconf)Prerequisite Macros::), so it
is safe to put each macro in a separate file.  Each file should have no
side effects but macro definitions.  Especially, any call to 'AC_PREREQ'
should be done inside the defined macro, not at the beginning of the
file.

   Starting with Automake 1.8, 'aclocal' will warn about all underquoted
calls to 'AC_DEFUN'.  We realize this will annoy a lot of people,
because 'aclocal' was not so strict in the past and many third party
macros are underquoted; and we have to apologize for this temporary
inconvenience.  The reason we have to be stricter is that a future
implementation of 'aclocal' (*note Future of aclocal::) will have to
temporarily include all of these third party '.m4' files, maybe several
times, including even files that are not actually needed.  Doing so
should alleviate many problems of the current implementation, however it
requires a stricter style from the macro authors.  Hopefully it is easy
to revise the existing macros.  For instance,

     # bad style
     AC_PREREQ(2.68)
     AC_DEFUN(AX_FOOBAR,
     [AC_REQUIRE([AX_SOMETHING])dnl
     AX_FOO
     AX_BAR
     ])

should be rewritten as

     AC_DEFUN([AX_FOOBAR],
     [AC_PREREQ([2.68])dnl
     AC_REQUIRE([AX_SOMETHING])dnl
     AX_FOO
     AX_BAR
     ])

   Wrapping the 'AC_PREREQ' call inside the macro ensures that Autoconf
2.68 will not be required if 'AX_FOOBAR' is not actually used.  Most
importantly, quoting the first argument of 'AC_DEFUN' allows the macro
to be redefined or included twice (otherwise this first argument would
be expanded during the second definition).  For consistency we like to
quote even arguments such as '2.68' that do not require it.

   If you have been directed here by the 'aclocal' diagnostic but are
not the maintainer of the implicated macro, you will want to contact the
maintainer of that macro.  Please make sure you have the latest version
of the macro and that the problem hasn't already been reported before
doing so: people tend to work faster when they aren't flooded by mails.

   Another situation where 'aclocal' is commonly used is to manage
macros that are used locally by the package, *note Local Macros::.

6.3.4 Handling Local Macros
---------------------------

Feature tests offered by Autoconf do not cover all needs.  People often
have to supplement existing tests with their own macros, or with
third-party macros.

   There are two ways to organize custom macros in a package.

   The first possibility (the historical practice) is to list all your
macros in 'acinclude.m4'.  This file will be included in 'aclocal.m4'
when you run 'aclocal', and its macro(s) will henceforth be visible to
'autoconf'.  However if it contains numerous macros, it will rapidly
become difficult to maintain, and it will be almost impossible to share
macros between packages.

   The second possibility, which we do recommend, is to write each macro
in its own file and gather all these files in a directory.  This
directory is usually called 'm4/'.  Then it's enough to update
'configure.ac' by adding a proper call to 'AC_CONFIG_MACRO_DIRS':

     AC_CONFIG_MACRO_DIRS([m4])

   'aclocal' will then take care of automatically adding 'm4/' to its
search path for m4 files.

   When 'aclocal' is run, it will build an 'aclocal.m4' that
'm4_include's any file from 'm4/' that defines a required macro.  Macros
not found locally will still be searched in system-wide directories, as
explained in *note Macro Search Path::.

   Custom macros should be distributed for the same reason that
'configure.ac' is: so that other people have all the sources of your
package if they want to work on it.  Actually, this distribution happens
automatically because all 'm4_include'd files are distributed.

   However there is no consensus on the distribution of third-party
macros that your package may use.  Many libraries install their own
macro in the system-wide 'aclocal' directory (*note Extending
aclocal::).  For instance, Guile ships with a file called 'guile.m4'
that contains the macro 'GUILE_FLAGS' that can be used to define setup
compiler and linker flags appropriate for using Guile.  Using
'GUILE_FLAGS' in 'configure.ac' will cause 'aclocal' to copy 'guile.m4'
into 'aclocal.m4', but as 'guile.m4' is not part of the project, it will
not be distributed.  Technically, that means a user who needs to rebuild
'aclocal.m4' will have to install Guile first.  This is probably OK, if
Guile already is a requirement to build the package.  However, if Guile
is only an optional feature, or if your package might run on
architectures where Guile cannot be installed, this requirement will
hinder development.  An easy solution is to copy such third-party macros
in your local 'm4/' directory so they get distributed.

   Since Automake 1.10, 'aclocal' offers the option '--install' to copy
these system-wide third-party macros in your local macro directory,
helping to solve the above problem.

   With this setup, system-wide macros will be copied to 'm4/' the first
time you run 'aclocal'.  Then the locally installed macros will have
precedence over the system-wide installed macros each time 'aclocal' is
run again.

   One reason why you should keep '--install' in the flags even after
the first run is that when you later edit 'configure.ac' and depend on a
new macro, this macro will be installed in your 'm4/' automatically.
Another one is that serial numbers (*note Serials::) can be used to
update the macros in your source tree automatically when new system-wide
versions are installed.  A serial number should be a single line of the
form

     #serial NNN

where NNN contains only digits and dots.  It should appear in the M4
file before any macro definition.  It is a good practice to maintain a
serial number for each macro you distribute, even if you do not use the
'--install' option of 'aclocal': this allows other people to use it.

6.3.5 Serial Numbers
--------------------

Because third-party macros defined in '*.m4' files are naturally shared
between multiple projects, some people like to version them.  This makes
it easier to tell which of two M4 files is newer.  Since at least 1996,
the tradition is to use a '#serial' line for this.

   A serial number should be a single line of the form

     # serial VERSION

where VERSION is a version number containing only digits and dots.
Usually people use a single integer, and they increment it each time
they change the macro (hence the name of "serial").  Such a line should
appear in the M4 file before any macro definition.

   The '#' must be the first character on the line, and it is OK to have
extra words after the version, as in

     #serial VERSION GARBAGE

   Normally these serial numbers are completely ignored by 'aclocal' and
'autoconf', like any genuine comment.  However when using 'aclocal''s
'--install' feature, these serial numbers will modify the way 'aclocal'
selects the macros to install in the package: if two files with the same
basename exist in your search path, and if at least one of them uses a
'#serial' line, 'aclocal' will ignore the file that has the older
'#serial' line (or the file that has none).

   Note that a serial number applies to a whole M4 file, not to any
macro it contains.  A file can contains multiple macros, but only one
serial.

   Here is a use case that illustrates the use of '--install' and its
interaction with serial numbers.  Let's assume we maintain a package
called MyPackage, the 'configure.ac' of which requires a third-party
macro 'AX_THIRD_PARTY' defined in '/usr/share/aclocal/thirdparty.m4' as
follows:

     # serial 1
     AC_DEFUN([AX_THIRD_PARTY], [...])

   MyPackage uses an 'm4/' directory to store local macros as explained
in *note Local Macros::, and has

     AC_CONFIG_MACRO_DIRS([m4])

in its 'configure.ac'.

   Initially the 'm4/' directory is empty.  The first time we run
'aclocal --install', it will notice that

   * 'configure.ac' uses 'AX_THIRD_PARTY'
   * No local macros define 'AX_THIRD_PARTY'
   * '/usr/share/aclocal/thirdparty.m4' defines 'AX_THIRD_PARTY' with
     serial 1.

Because '/usr/share/aclocal/thirdparty.m4' is a system-wide macro and
'aclocal' was given the '--install' option, it will copy this file in
'm4/thirdparty.m4', and output an 'aclocal.m4' that contains
'm4_include([m4/thirdparty.m4])'.

   The next time 'aclocal --install' is run, something different
happens.  'aclocal' notices that

   * 'configure.ac' uses 'AX_THIRD_PARTY'
   * 'm4/thirdparty.m4' defines 'AX_THIRD_PARTY' with serial 1.
   * '/usr/share/aclocal/thirdparty.m4' defines 'AX_THIRD_PARTY' with
     serial 1.

Because both files have the same serial number, 'aclocal' uses the first
it found in its search path order (*note Macro Search Path::).
'aclocal' therefore ignores '/usr/share/aclocal/thirdparty.m4' and
outputs an 'aclocal.m4' that contains 'm4_include([m4/thirdparty.m4])'.

   Local directories specified with '-I' are always searched before
system-wide directories, so a local file will always be preferred to the
system-wide file in case of equal serial numbers.

   Now suppose the system-wide third-party macro is changed.  This can
happen if the package installing this macro is updated.  Let's suppose
the new macro has serial number 2.  The next time 'aclocal --install' is
run the situation is the following:

   * 'configure.ac' uses 'AX_THIRD_PARTY'
   * 'm4/thirdparty.m4' defines 'AX_THIRD_PARTY' with serial 1.
   * '/usr/share/aclocal/thirdparty.m4' defines 'AX_THIRD_PARTY' with
     serial 2.

When 'aclocal' sees a greater serial number, it immediately forgets
anything it knows from files that have the same basename and a smaller
serial number.  So after it has found '/usr/share/aclocal/thirdparty.m4'
with serial 2, 'aclocal' will proceed as if it had never seen
'm4/thirdparty.m4'.  This brings us back to a situation similar to that
at the beginning of our example, where no local file defined the macro.
'aclocal' will install the new version of the macro in
'm4/thirdparty.m4', in this case overriding the old version.  MyPackage
just had its macro updated as a side effect of running 'aclocal'.

   If you are leery of letting 'aclocal' update your local macro, you
can run 'aclocal --diff' to review the changes 'aclocal --install' would
perform on these macros.

   Finally, note that the '--force' option of 'aclocal' has absolutely
no effect on the files installed by '--install'.  For instance, if you
have modified your local macros, do not expect '--install --force' to
replace the local macros by their system-wide versions.  If you want to
do so, simply erase the local macros you want to revert, and run
'aclocal --install'.

6.3.6 The Future of 'aclocal'
-----------------------------

'aclocal' is expected to disappear.  This feature really should not be
offered by Automake.  Automake should focus on generating 'Makefile's;
dealing with M4 macros really is Autoconf's job.  The fact that some
people install Automake just to use 'aclocal', but do not use 'automake'
otherwise is an indication of how that feature is misplaced.

   The new implementation will probably be done slightly differently.
For instance, it could enforce the 'm4/'-style layout discussed in *note
Local Macros::.

   We have no idea when and how this will happen.  This has been
discussed several times in the past, but someone still has to commit to
that non-trivial task.

   From the user point of view, 'aclocal''s removal might turn out to be
painful.  There is a simple precaution that you may take to make that
switch more seamless: never call 'aclocal' yourself.  Keep this guy
under the exclusive control of 'autoreconf' and Automake's rebuild
rules.  Hopefully you won't need to worry about things breaking, when
'aclocal' disappears, because everything will have been taken care of.
If otherwise you used to call 'aclocal' directly yourself or from some
script, you will quickly notice the change.

   Many packages come with a script called 'bootstrap.sh' or
'autogen.sh', that will just call 'aclocal', 'libtoolize', 'gettextize'
or 'autopoint', 'autoconf', 'autoheader', and 'automake' in the right
order.  Actually this is precisely what 'autoreconf' can do for you.  If
your package has such a 'bootstrap.sh' or 'autogen.sh' script, consider
using 'autoreconf'.  That should simplify its logic a lot (less things
to maintain, yum!), it's even likely you will not need the script
anymore, and more to the point you will not call 'aclocal' directly
anymore.

   For the time being, third-party packages should continue to install
public macros into '/usr/share/aclocal/'.  If 'aclocal' is replaced by
another tool it might make sense to rename the directory, but supporting
'/usr/share/aclocal/' for backward compatibility should be really easy
provided all macros are properly written (*note Extending aclocal::).

6.4 Autoconf macros supplied with Automake
==========================================

Automake ships with several Autoconf macros that you can use from your
'configure.ac'.  When you use one of them it will be included by
'aclocal' in 'aclocal.m4'.

6.4.1 Public Macros
-------------------

'AM_INIT_AUTOMAKE([OPTIONS])'
     Runs many macros required for proper operation of the generated
     Makefiles.

     Today, 'AM_INIT_AUTOMAKE' is called with a single argument: a
     space-separated list of Automake options that should be applied to
     every 'Makefile.am' in the tree.  The effect is as if each option
     were listed in 'AUTOMAKE_OPTIONS' (*note Options::).

     This macro can also be called in another, _deprecated_ form:
     'AM_INIT_AUTOMAKE(PACKAGE, VERSION, [NO-DEFINE])'.  In this form,
     there are two required arguments: the package and the version
     number.  This usage is mostly obsolete because the PACKAGE and
     VERSION can be obtained from Autoconf's 'AC_INIT' macro.  However,
     differently from what happens for 'AC_INIT' invocations, this
     'AM_INIT_AUTOMAKE' invocation supports shell variables' expansions
     in the 'PACKAGE' and 'VERSION' arguments, and this can be still be
     useful in some selected situations.  Our hope is that future
     Autoconf versions will improve their support for package versions
     defined dynamically at configure runtime; when (and if) this
     happens, support for the two-args 'AM_INIT_AUTOMAKE' invocation
     will likely be removed from Automake.

     If your 'configure.ac' has:

          AC_INIT([src/foo.c])
          AM_INIT_AUTOMAKE([mumble], [1.5])

     you should modernize it as follows:

          AC_INIT([mumble], [1.5])
          AC_CONFIG_SRCDIR([src/foo.c])
          AM_INIT_AUTOMAKE

     Note that if you're upgrading your 'configure.ac' from an earlier
     version of Automake, it is not always correct to simply move the
     package and version arguments from 'AM_INIT_AUTOMAKE' directly to
     'AC_INIT', as in the example above.  The first argument to
     'AC_INIT' should be the name of your package (e.g., 'GNU
     Automake'), not the tarball name (e.g., 'automake') that you used
     to pass to 'AM_INIT_AUTOMAKE'.  Autoconf tries to derive a tarball
     name from the package name, which should work for most but not all
     package names.  (If it doesn't work for yours, you can use the
     four-argument form of 'AC_INIT' to provide the tarball name
     explicitly).

     By default this macro 'AC_DEFINE''s 'PACKAGE' and 'VERSION'.  This
     can be avoided by passing the 'no-define' option (*note List of
     Automake options::):
          AM_INIT_AUTOMAKE([no-define ...])

'AM_PATH_LISPDIR'
     Searches for the program 'emacs', and, if found, sets the output
     variable 'lispdir' to the full path to Emacs' site-lisp directory.

     Note that this test assumes the 'emacs' found to be a version that
     supports Emacs Lisp (such as GNU Emacs or XEmacs).  Other emacsen
     can cause this test to hang (some, like old versions of MicroEmacs,
     start up in interactive mode, requiring 'C-x C-c' to exit, which is
     hardly obvious for a non-emacs user).  In most cases, however, you
     should be able to use 'C-c' to kill the test.  In order to avoid
     problems, you can set 'EMACS' to "no" in the environment, or use
     the '--with-lispdir' option to 'configure' to explicitly set the
     correct path (if you're sure you have an 'emacs' that supports
     Emacs Lisp).

'AM_PROG_AR([ACT-IF-FAIL])'
     You must use this macro when you use the archiver in your project,
     if you want support for unusual archivers such as Microsoft 'lib'.
     The content of the optional argument is executed if the archiver
     interface is not recognized; the default action is to abort
     configure with an error message.

'AM_PROG_AS'
     Use this macro when you have assembly code in your project.  This
     will choose the assembler for you (by default the C compiler) and
     set 'CCAS', and will also set 'CCASFLAGS' if required.

'AM_PROG_CC_C_O'
     This is an obsolescent macro that checks that the C compiler
     supports the '-c' and '-o' options together.  Note that, since
     Automake 1.14, the 'AC_PROG_CC' is rewritten to implement such
     checks itself, and thus the explicit use of 'AM_PROG_CC_C_O' should
     no longer be required.

'AM_PROG_LEX'
     Like 'AC_PROG_LEX' (*note Particular Program Checks:
     (autoconf)Particular Programs.), but uses the 'missing' script on
     systems that do not have 'lex'.  HP-UX 10 is one such system.

'AM_PROG_GCJ'
     This macro finds the 'gcj' program or causes an error.  It sets
     'GCJ' and 'GCJFLAGS'.  'gcj' is the Java front-end to the GNU
     Compiler Collection.

'AM_PROG_UPC([COMPILER-SEARCH-LIST])'
     Find a compiler for Unified Parallel C and define the 'UPC'
     variable.  The default COMPILER-SEARCH-LIST is 'upcc upc'.  This
     macro will abort 'configure' if no Unified Parallel C compiler is
     found.

'AM_MISSING_PROG(NAME, PROGRAM)'
     Find a maintainer tool PROGRAM and define the NAME environment
     variable with its location.  If PROGRAM is not detected, then NAME
     will instead invoke the 'missing' script, in order to give useful
     advice to the user about the missing maintainer tool.  *Note
     maintainer-mode::, for more information on when the 'missing'
     script is appropriate.

'AM_SILENT_RULES'
     Control the machinery for less verbose build output (*note Automake
     Silent Rules::).

'AM_WITH_DMALLOC'
     Add support for the Dmalloc package (http://dmalloc.com/).  If the
     user runs 'configure' with '--with-dmalloc', then define
     'WITH_DMALLOC' and add '-ldmalloc' to 'LIBS'.

6.4.2 Obsolete Macros
---------------------

Although using some of the following macros was required in past
releases, you should not use any of them in new code.  _All these macros
will be removed in the next major Automake version_; if you are still
using them, running 'autoupdate' should adjust your 'configure.ac'
automatically (*note Using 'autoupdate' to Modernize 'configure.ac':
(autoconf)autoupdate Invocation.).  _Do it NOW!_

'AM_PROG_MKDIR_P'

     From Automake 1.8 to 1.9.6 this macro used to define the output
     variable 'mkdir_p' to one of 'mkdir -p', 'install-sh -d', or
     'mkinstalldirs'.

     Nowadays Autoconf provides a similar functionality with
     'AC_PROG_MKDIR_P' (*note Particular Program Checks:
     (autoconf)Particular Programs.), however this defines the output
     variable 'MKDIR_P' instead.  In case you are still using the
     'AM_PROG_MKDIR_P' macro in your 'configure.ac', or its provided
     variable '$(mkdir_p)' in your 'Makefile.am', you are advised to
     switch ASAP to the more modern Autoconf-provided interface instead;
     both the macro and the variable might be removed in a future major
     Automake release.

6.4.3 Private Macros
--------------------

The following macros are private macros you should not call directly.
They are called by the other public macros when appropriate.  Do not
rely on them, as they might be changed in a future version.  Consider
them as implementation details; or better, do not consider them at all:
skip this section!

'_AM_DEPENDENCIES'
'AM_SET_DEPDIR'
'AM_DEP_TRACK'
'AM_OUTPUT_DEPENDENCY_COMMANDS'
     These macros are used to implement Automake's automatic dependency
     tracking scheme.  They are called automatically by Automake when
     required, and there should be no need to invoke them manually.

'AM_MAKE_INCLUDE'
     This macro is used to discover how the user's 'make' handles
     'include' statements.  This macro is automatically invoked when
     needed; there should be no need to invoke it manually.

'AM_PROG_INSTALL_STRIP'
     This is used to find a version of 'install' that can be used to
     strip a program at installation time.  This macro is automatically
     included when required.

'AM_SANITY_CHECK'
     This checks to make sure that a file created in the build directory
     is newer than a file in the source directory.  This can fail on
     systems where the clock is set incorrectly.  This macro is
     automatically run from 'AM_INIT_AUTOMAKE'.

7 Directories
*************

For simple projects that distribute all files in the same directory it
is enough to have a single 'Makefile.am' that builds everything in
place.

   In larger projects, it is common to organize files in different
directories, in a tree.  For example, there could be a directory for the
program's source, one for the testsuite, and one for the documentation;
or, for very large projects, there could be one directory per program,
per library or per module.

   The traditional approach is to build these subdirectories
recursively, employing _make recursion_: each directory contains its own
'Makefile', and when 'make' is run from the top-level directory, it
enters each subdirectory in turn, and invokes there a new 'make'
instance to build the directory's contents.

   Because this approach is very widespread, Automake offers built-in
support for it.  However, it is worth nothing that the use of make
recursion has its own serious issues and drawbacks, and that it's well
possible to have packages with a multi directory layout that make little
or no use of such recursion (examples of such packages are GNU Bison and
GNU Automake itself); see also the *note Alternative:: section below.

7.1 Recursing subdirectories
============================

In packages using make recursion, the top level 'Makefile.am' must tell
Automake which subdirectories are to be built.  This is done via the
'SUBDIRS' variable.

   The 'SUBDIRS' variable holds a list of subdirectories in which
building of various sorts can occur.  The rules for many targets (e.g.,
'all') in the generated 'Makefile' will run commands both locally and in
all specified subdirectories.  Note that the directories listed in
'SUBDIRS' are not required to contain 'Makefile.am's; only 'Makefile's
(after configuration).  This allows inclusion of libraries from packages
that do not use Automake (such as 'gettext'; see also *note Third-Party
Makefiles::).

   In packages that use subdirectories, the top-level 'Makefile.am' is
often very short.  For instance, here is the 'Makefile.am' from the GNU
Hello distribution:

     EXTRA_DIST = BUGS ChangeLog.O README-alpha
     SUBDIRS = doc intl po src tests

   When Automake invokes 'make' in a subdirectory, it uses the value of
the 'MAKE' variable.  It passes the value of the variable 'AM_MAKEFLAGS'
to the 'make' invocation; this can be set in 'Makefile.am' if there are
flags you must always pass to 'make'.

   The directories mentioned in 'SUBDIRS' are usually direct children of
the current directory, each subdirectory containing its own
'Makefile.am' with a 'SUBDIRS' pointing to deeper subdirectories.
Automake can be used to construct packages of arbitrary depth this way.

   By default, Automake generates 'Makefiles' that work depth-first in
postfix order: the subdirectories are built before the current
directory.  However, it is possible to change this ordering.  You can do
this by putting '.' into 'SUBDIRS'.  For instance, putting '.' first
will cause a prefix ordering of directories.

   Using

     SUBDIRS = lib src . test

will cause 'lib/' to be built before 'src/', then the current directory
will be built, finally the 'test/' directory will be built.  It is
customary to arrange test directories to be built after everything else
since they are meant to test what has been constructed.

   In addition to the built-in recursive targets defined by Automake
('all', 'check', etc.), the developer can also define his own recursive
targets.  That is done by passing the names of such targets as arguments
to the m4 macro 'AM_EXTRA_RECURSIVE_TARGETS' in 'configure.ac'.
Automake generates rules to handle the recursion for such targets; and
the developer can define real actions for them by defining corresponding
'-local' targets.

     % cat configure.ac
     AC_INIT([pkg-name], [1.0]
     AM_INIT_AUTOMAKE
     AM_EXTRA_RECURSIVE_TARGETS([foo])
     AC_CONFIG_FILES([Makefile sub/Makefile sub/src/Makefile])
     AC_OUTPUT
     % cat Makefile.am
     SUBDIRS = sub
     foo-local:
             @echo This will be run by "make foo".
     % cat sub/Makefile.am
     SUBDIRS = src
     % cat sub/src/Makefile.am
     foo-local:
             @echo This too will be run by a "make foo" issued either in
             @echo the 'sub/src/' directory, the 'sub/' directory, or the
             @echo top-level directory.

7.2 Conditional Subdirectories
==============================

It is possible to define the 'SUBDIRS' variable conditionally if, like
in the case of GNU Inetutils, you want to only build a subset of the
entire package.

   To illustrate how this works, let's assume we have two directories
'src/' and 'opt/'.  'src/' should always be built, but we want to decide
in 'configure' whether 'opt/' will be built or not.  (For this example
we will assume that 'opt/' should be built when the variable '$want_opt'
was set to 'yes'.)

   Running 'make' should thus recurse into 'src/' always, and then maybe
in 'opt/'.

   However 'make dist' should always recurse into both 'src/' and
'opt/'.  Because 'opt/' should be distributed even if it is not needed
in the current configuration.  This means 'opt/Makefile' should be
created _unconditionally_.

   There are two ways to setup a project like this.  You can use
Automake conditionals (*note Conditionals::) or use Autoconf 'AC_SUBST'
variables (*note Setting Output Variables: (autoconf)Setting Output
Variables.).  Using Automake conditionals is the preferred solution.
Before we illustrate these two possibilities, let's introduce
'DIST_SUBDIRS'.

7.2.1 'SUBDIRS' vs. 'DIST_SUBDIRS'
----------------------------------

Automake considers two sets of directories, defined by the variables
'SUBDIRS' and 'DIST_SUBDIRS'.

   'SUBDIRS' contains the subdirectories of the current directory that
must be built (*note Subdirectories::).  It must be defined manually;
Automake will never guess a directory is to be built.  As we will see in
the next two sections, it is possible to define it conditionally so that
some directory will be omitted from the build.

   'DIST_SUBDIRS' is used in rules that need to recurse in all
directories, even those that have been conditionally left out of the
build.  Recall our example where we may not want to build subdirectory
'opt/', but yet we want to distribute it?  This is where 'DIST_SUBDIRS'
comes into play: 'opt' may not appear in 'SUBDIRS', but it must appear
in 'DIST_SUBDIRS'.

   Precisely, 'DIST_SUBDIRS' is used by 'make maintainer-clean', 'make
distclean' and 'make dist'.  All other recursive rules use 'SUBDIRS'.

   If 'SUBDIRS' is defined conditionally using Automake conditionals,
Automake will define 'DIST_SUBDIRS' automatically from the possible
values of 'SUBDIRS' in all conditions.

   If 'SUBDIRS' contains 'AC_SUBST' variables, 'DIST_SUBDIRS' will not
be defined correctly because Automake does not know the possible values
of these variables.  In this case 'DIST_SUBDIRS' needs to be defined
manually.

7.2.2 Subdirectories with 'AM_CONDITIONAL'
------------------------------------------

'configure' should output the 'Makefile' for each directory and define a
condition into which 'opt/' should be built.

     ...
     AM_CONDITIONAL([COND_OPT], [test "$want_opt" = yes])
     AC_CONFIG_FILES([Makefile src/Makefile opt/Makefile])
     ...

   Then 'SUBDIRS' can be defined in the top-level 'Makefile.am' as
follows.

     if COND_OPT
       MAYBE_OPT = opt
     endif
     SUBDIRS = src $(MAYBE_OPT)

   As you can see, running 'make' will rightly recurse into 'src/' and
maybe 'opt/'.

   As you can't see, running 'make dist' will recurse into both 'src/'
and 'opt/' directories because 'make dist', unlike 'make all', doesn't
use the 'SUBDIRS' variable.  It uses the 'DIST_SUBDIRS' variable.

   In this case Automake will define 'DIST_SUBDIRS = src opt'
automatically because it knows that 'MAYBE_OPT' can contain 'opt' in
some condition.

7.2.3 Subdirectories with 'AC_SUBST'
------------------------------------

Another possibility is to define 'MAYBE_OPT' from './configure' using
'AC_SUBST':

     ...
     if test "$want_opt" = yes; then
       MAYBE_OPT=opt
     else
       MAYBE_OPT=
     fi
     AC_SUBST([MAYBE_OPT])
     AC_CONFIG_FILES([Makefile src/Makefile opt/Makefile])
     ...

   In this case the top-level 'Makefile.am' should look as follows.

     SUBDIRS = src $(MAYBE_OPT)
     DIST_SUBDIRS = src opt

   The drawback is that since Automake cannot guess what the possible
values of 'MAYBE_OPT' are, it is necessary to define 'DIST_SUBDIRS'.

7.2.4 Unconfigured Subdirectories
---------------------------------

The semantics of 'DIST_SUBDIRS' are often misunderstood by some users
that try to _configure and build_ subdirectories conditionally.  Here by
configuring we mean creating the 'Makefile' (it might also involve
running a nested 'configure' script: this is a costly operation that
explains why people want to do it conditionally, but only the 'Makefile'
is relevant to the discussion).

   The above examples all assume that every 'Makefile' is created, even
in directories that are not going to be built.  The simple reason is
that we want 'make dist' to distribute even the directories that are not
being built (e.g., platform-dependent code), hence 'make dist' must
recurse into the subdirectory, hence this directory must be configured
and appear in 'DIST_SUBDIRS'.

   Building packages that do not configure every subdirectory is a
tricky business, and we do not recommend it to the novice as it is easy
to produce an incomplete tarball by mistake.  We will not discuss this
topic in depth here, yet for the adventurous here are a few rules to
remember.

   * 'SUBDIRS' should always be a subset of 'DIST_SUBDIRS'.

     It makes little sense to have a directory in 'SUBDIRS' that is not
     in 'DIST_SUBDIRS'.  Think of the former as a way to tell which
     directories listed in the latter should be built.
   * Any directory listed in 'DIST_SUBDIRS' and 'SUBDIRS' must be
     configured.

     I.e., the 'Makefile' must exists or the recursive 'make' rules will
     not be able to process the directory.
   * Any configured directory must be listed in 'DIST_SUBDIRS'.

     So that the cleaning rules remove the generated 'Makefile's.  It
     would be correct to see 'DIST_SUBDIRS' as a variable that lists all
     the directories that have been configured.

   In order to prevent recursion in some unconfigured directory you must
therefore ensure that this directory does not appear in 'DIST_SUBDIRS'
(and 'SUBDIRS').  For instance, if you define 'SUBDIRS' conditionally
using 'AC_SUBST' and do not define 'DIST_SUBDIRS' explicitly, it will be
default to '$(SUBDIRS)'; another possibility is to force 'DIST_SUBDIRS =
$(SUBDIRS)'.

   Of course, directories that are omitted from 'DIST_SUBDIRS' will not
be distributed unless you make other arrangements for this to happen
(for instance, always running 'make dist' in a configuration where all
directories are known to appear in 'DIST_SUBDIRS'; or writing a
'dist-hook' target to distribute these directories).

   In few packages, unconfigured directories are not even expected to be
distributed.  Although these packages do not require the aforementioned
extra arrangements, there is another pitfall.  If the name of a
directory appears in 'SUBDIRS' or 'DIST_SUBDIRS', 'automake' will make
sure the directory exists.  Consequently 'automake' cannot be run on
such a distribution when one directory has been omitted.  One way to
avoid this check is to use the 'AC_SUBST' method to declare conditional
directories; since 'automake' does not know the values of 'AC_SUBST'
variables it cannot ensure the corresponding directory exists.

7.3 An Alternative Approach to Subdirectories
=============================================

If you've ever read Peter Miller's excellent paper, Recursive Make
Considered Harmful (http://miller.emu.id.au/pmiller/books/rmch/), the
preceding sections on the use of make recursion will probably come as
unwelcome advice.  For those who haven't read the paper, Miller's main
thesis is that recursive 'make' invocations are both slow and
error-prone.

   Automake provides sufficient cross-directory support (1) to enable
you to write a single 'Makefile.am' for a complex multi-directory
package.

   By default an installable file specified in a subdirectory will have
its directory name stripped before installation.  For instance, in this
example, the header file will be installed as '$(includedir)/stdio.h':

     include_HEADERS = inc/stdio.h

   However, the 'nobase_' prefix can be used to circumvent this path
stripping.  In this example, the header file will be installed as
'$(includedir)/sys/types.h':

     nobase_include_HEADERS = sys/types.h

   'nobase_' should be specified first when used in conjunction with
either 'dist_' or 'nodist_' (*note Fine-grained Distribution Control::).
For instance:

     nobase_dist_pkgdata_DATA = images/vortex.pgm sounds/whirl.ogg

   Finally, note that a variable using the 'nobase_' prefix can often be
replaced by several variables, one for each destination directory (*note
Uniform::).  For instance, the last example could be rewritten as
follows:

     imagesdir = $(pkgdatadir)/images
     soundsdir = $(pkgdatadir)/sounds
     dist_images_DATA = images/vortex.pgm
     dist_sounds_DATA = sounds/whirl.ogg

This latter syntax makes it possible to change one destination directory
without changing the layout of the source tree.

   Currently, 'nobase_*_LTLIBRARIES' are the only exception to this
rule, in that there is no particular installation order guarantee for an
otherwise equivalent set of variables without 'nobase_' prefix.

   ---------- Footnotes ----------

   (1) We believe.  This work is new and there are probably warts.
*Note Introduction::, for information on reporting bugs.

7.4 Nesting Packages
====================

In the GNU Build System, packages can be nested to arbitrary depth.
This means that a package can embed other packages with their own
'configure', 'Makefile's, etc.

   These other packages should just appear as subdirectories of their
parent package.  They must be listed in 'SUBDIRS' like other ordinary
directories.  However the subpackage's 'Makefile's should be output by
its own 'configure' script, not by the parent's 'configure'.  This is
achieved using the 'AC_CONFIG_SUBDIRS' Autoconf macro (*note
AC_CONFIG_SUBDIRS: (autoconf)Subdirectories.).

   Here is an example package for an 'arm' program that links with a
'hand' library that is a nested package in subdirectory 'hand/'.

   'arm''s 'configure.ac':

     AC_INIT([arm], [1.0])
     AC_CONFIG_AUX_DIR([.])
     AM_INIT_AUTOMAKE
     AC_PROG_CC
     AC_CONFIG_FILES([Makefile])
     # Call hand's ./configure script recursively.
     AC_CONFIG_SUBDIRS([hand])
     AC_OUTPUT

   'arm''s 'Makefile.am':

     # Build the library in the hand subdirectory first.
     SUBDIRS = hand

     # Include hand's header when compiling this directory.
     AM_CPPFLAGS = -I$(srcdir)/hand

     bin_PROGRAMS = arm
     arm_SOURCES = arm.c
     # link with the hand library.
     arm_LDADD = hand/libhand.a

   Now here is 'hand''s 'hand/configure.ac':

     AC_INIT([hand], [1.2])
     AC_CONFIG_AUX_DIR([.])
     AM_INIT_AUTOMAKE
     AC_PROG_CC
     AM_PROG_AR
     AC_PROG_RANLIB
     AC_CONFIG_FILES([Makefile])
     AC_OUTPUT

and its 'hand/Makefile.am':

     lib_LIBRARIES = libhand.a
     libhand_a_SOURCES = hand.c

   When 'make dist' is run from the top-level directory it will create
an archive 'arm-1.0.tar.gz' that contains the 'arm' code as well as the
'hand' subdirectory.  This package can be built and installed like any
ordinary package, with the usual './configure && make && make install'
sequence (the 'hand' subpackage will be built and installed by the
process).

   When 'make dist' is run from the hand directory, it will create a
self-contained 'hand-1.2.tar.gz' archive.  So although it appears to be
embedded in another package, it can still be used separately.

   The purpose of the 'AC_CONFIG_AUX_DIR([.])' instruction is to force
Automake and Autoconf to search for auxiliary scripts in the current
directory.  For instance, this means that there will be two copies of
'install-sh': one in the top-level of the 'arm' package, and another one
in the 'hand/' subdirectory for the 'hand' package.

   The historical default is to search for these auxiliary scripts in
the parent directory and the grandparent directory.  So if the
'AC_CONFIG_AUX_DIR([.])' line was removed from 'hand/configure.ac', that
subpackage would share the auxiliary script of the 'arm' package.  This
may looks like a gain in size (a few kilobytes), but it is actually a
loss of modularity as the 'hand' subpackage is no longer self-contained
('make dist' in the subdirectory will not work anymore).

   Packages that do not use Automake need more work to be integrated
this way.  *Note Third-Party Makefiles::.

8 Building Programs and Libraries
*********************************

A large part of Automake's functionality is dedicated to making it easy
to build programs and libraries.

8.1 Building a program
======================

In order to build a program, you need to tell Automake which sources are
part of it, and which libraries it should be linked with.

   This section also covers conditional compilation of sources or
programs.  Most of the comments about these also apply to libraries
(*note A Library::) and libtool libraries (*note A Shared Library::).

8.1.1 Defining program sources
------------------------------

In a directory containing source that gets built into a program (as
opposed to a library or a script), the 'PROGRAMS' primary is used.
Programs can be installed in 'bindir', 'sbindir', 'libexecdir',
'pkglibexecdir', or not at all ('noinst_').  They can also be built only
for 'make check', in which case the prefix is 'check_'.

   For instance:

     bin_PROGRAMS = hello

   In this simple case, the resulting 'Makefile.in' will contain code to
generate a program named 'hello'.

   Associated with each program are several assisting variables that are
named after the program.  These variables are all optional, and have
reasonable defaults.  Each variable, its use, and default is spelled out
below; we use the "hello" example throughout.

   The variable 'hello_SOURCES' is used to specify which source files
get built into an executable:

     hello_SOURCES = hello.c version.c getopt.c getopt1.c getopt.h system.h

   This causes each mentioned '.c' file to be compiled into the
corresponding '.o'.  Then all are linked to produce 'hello'.

   If 'hello_SOURCES' is not specified, then it defaults to the single
file 'hello.c' (*note Default _SOURCES::).

   Multiple programs can be built in a single directory.  Multiple
programs can share a single source file, which must be listed in each
'_SOURCES' definition.

   Header files listed in a '_SOURCES' definition will be included in
the distribution but otherwise ignored.  In case it isn't obvious, you
should not include the header file generated by 'configure' in a
'_SOURCES' variable; this file should not be distributed.  Lex ('.l')
and Yacc ('.y') files can also be listed; see *note Yacc and Lex::.

8.1.2 Linking the program
-------------------------

If you need to link against libraries that are not found by 'configure',
you can use 'LDADD' to do so.  This variable is used to specify
additional objects or libraries to link with; it is inappropriate for
specifying specific linker flags, you should use 'AM_LDFLAGS' for this
purpose.

   Sometimes, multiple programs are built in one directory but do not
share the same link-time requirements.  In this case, you can use the
'PROG_LDADD' variable (where PROG is the name of the program as it
appears in some '_PROGRAMS' variable, and usually written in lowercase)
to override 'LDADD'.  If this variable exists for a given program, then
that program is not linked using 'LDADD'.

   For instance, in GNU cpio, 'pax', 'cpio' and 'mt' are linked against
the library 'libcpio.a'.  However, 'rmt' is built in the same directory,
and has no such link requirement.  Also, 'mt' and 'rmt' are only built
on certain architectures.  Here is what cpio's 'src/Makefile.am' looks
like (abridged):

     bin_PROGRAMS = cpio pax $(MT)
     libexec_PROGRAMS = $(RMT)
     EXTRA_PROGRAMS = mt rmt

     LDADD = ../lib/libcpio.a $(INTLLIBS)
     rmt_LDADD =

     cpio_SOURCES = ...
     pax_SOURCES = ...
     mt_SOURCES = ...
     rmt_SOURCES = ...

   'PROG_LDADD' is inappropriate for passing program-specific linker
flags (except for '-l', '-L', '-dlopen' and '-dlpreopen').  So, use the
'PROG_LDFLAGS' variable for this purpose.

   It is also occasionally useful to have a program depend on some other
target that is not actually part of that program.  This can be done
using either the 'PROG_DEPENDENCIES' or the 'EXTRA_PROG_DEPENDENCIES'
variable.  Each program depends on the contents both variables, but no
further interpretation is done.

   Since these dependencies are associated to the link rule used to
create the programs they should normally list files used by the link
command.  That is '*.$(OBJEXT)', '*.a', or '*.la' files.  In rare cases
you may need to add other kinds of files such as linker scripts, but
_listing a source file in '_DEPENDENCIES' is wrong_.  If some source
file needs to be built before all the components of a program are built,
consider using the 'BUILT_SOURCES' variable instead (*note Sources::).

   If 'PROG_DEPENDENCIES' is not supplied, it is computed by Automake.
The automatically-assigned value is the contents of 'PROG_LDADD', with
most configure substitutions, '-l', '-L', '-dlopen' and '-dlpreopen'
options removed.  The configure substitutions that are left in are only
'$(LIBOBJS)' and '$(ALLOCA)'; these are left because it is known that
they will not cause an invalid value for 'PROG_DEPENDENCIES' to be
generated.

   *note Conditional Sources:: shows a situation where '_DEPENDENCIES'
may be used.

   The 'EXTRA_PROG_DEPENDENCIES' may be useful for cases where you
merely want to augment the 'automake'-generated 'PROG_DEPENDENCIES'
rather than replacing it.

   We recommend that you avoid using '-l' options in 'LDADD' or
'PROG_LDADD' when referring to libraries built by your package.
Instead, write the file name of the library explicitly as in the above
'cpio' example.  Use '-l' only to list third-party libraries.  If you
follow this rule, the default value of 'PROG_DEPENDENCIES' will list all
your local libraries and omit the other ones.

8.1.3 Conditional compilation of sources
----------------------------------------

You can't put a configure substitution (e.g., '@FOO@' or '$(FOO)' where
'FOO' is defined via 'AC_SUBST') into a '_SOURCES' variable.  The reason
for this is a bit hard to explain, but suffice to say that it simply
won't work.  Automake will give an error if you try to do this.

   Fortunately there are two other ways to achieve the same result.  One
is to use configure substitutions in '_LDADD' variables, the other is to
use an Automake conditional.

Conditional Compilation using '_LDADD' Substitutions
....................................................

Automake must know all the source files that could possibly go into a
program, even if not all the files are built in every circumstance.  Any
files that are only conditionally built should be listed in the
appropriate 'EXTRA_' variable.  For instance, if 'hello-linux.c' or
'hello-generic.c' were conditionally included in 'hello', the
'Makefile.am' would contain:

     bin_PROGRAMS = hello
     hello_SOURCES = hello-common.c
     EXTRA_hello_SOURCES = hello-linux.c hello-generic.c
     hello_LDADD = $(HELLO_SYSTEM)
     hello_DEPENDENCIES = $(HELLO_SYSTEM)

You can then setup the '$(HELLO_SYSTEM)' substitution from
'configure.ac':

     ...
     case $host in
       *linux*) HELLO_SYSTEM='hello-linux.$(OBJEXT)' ;;
       *)       HELLO_SYSTEM='hello-generic.$(OBJEXT)' ;;
     esac
     AC_SUBST([HELLO_SYSTEM])
     ...

   In this case, the variable 'HELLO_SYSTEM' should be replaced by
either 'hello-linux.o' or 'hello-generic.o', and added to both
'hello_DEPENDENCIES' and 'hello_LDADD' in order to be built and linked
in.

Conditional Compilation using Automake Conditionals
...................................................

An often simpler way to compile source files conditionally is to use
Automake conditionals.  For instance, you could use this 'Makefile.am'
construct to build the same 'hello' example:

     bin_PROGRAMS = hello
     if LINUX
     hello_SOURCES = hello-linux.c hello-common.c
     else
     hello_SOURCES = hello-generic.c hello-common.c
     endif

   In this case, 'configure.ac' should setup the 'LINUX' conditional
using 'AM_CONDITIONAL' (*note Conditionals::).

   When using conditionals like this you don't need to use the 'EXTRA_'
variable, because Automake will examine the contents of each variable to
construct the complete list of source files.

   If your program uses a lot of files, you will probably prefer a
conditional '+='.

     bin_PROGRAMS = hello
     hello_SOURCES = hello-common.c
     if LINUX
     hello_SOURCES += hello-linux.c
     else
     hello_SOURCES += hello-generic.c
     endif

8.1.4 Conditional compilation of programs
-----------------------------------------

Sometimes it is useful to determine the programs that are to be built at
configure time.  For instance, GNU 'cpio' only builds 'mt' and 'rmt'
under special circumstances.  The means to achieve conditional
compilation of programs are the same you can use to compile source files
conditionally: substitutions or conditionals.

Conditional Programs using 'configure' Substitutions
....................................................

In this case, you must notify Automake of all the programs that can
possibly be built, but at the same time cause the generated
'Makefile.in' to use the programs specified by 'configure'.  This is
done by having 'configure' substitute values into each '_PROGRAMS'
definition, while listing all optionally built programs in
'EXTRA_PROGRAMS'.

     bin_PROGRAMS = cpio pax $(MT)
     libexec_PROGRAMS = $(RMT)
     EXTRA_PROGRAMS = mt rmt

   As explained in *note EXEEXT::, Automake will rewrite 'bin_PROGRAMS',
'libexec_PROGRAMS', and 'EXTRA_PROGRAMS', appending '$(EXEEXT)' to each
binary.  Obviously it cannot rewrite values obtained at run-time through
'configure' substitutions, therefore you should take care of appending
'$(EXEEXT)' yourself, as in 'AC_SUBST([MT], ['mt${EXEEXT}'])'.

Conditional Programs using Automake Conditionals
................................................

You can also use Automake conditionals (*note Conditionals::) to select
programs to be built.  In this case you don't have to worry about
'$(EXEEXT)' or 'EXTRA_PROGRAMS'.

     bin_PROGRAMS = cpio pax
     if WANT_MT
       bin_PROGRAMS += mt
     endif
     if WANT_RMT
       libexec_PROGRAMS = rmt
     endif

8.2 Building a library
======================

Building a library is much like building a program.  In this case, the
name of the primary is 'LIBRARIES'.  Libraries can be installed in
'libdir' or 'pkglibdir'.

   *Note A Shared Library::, for information on how to build shared
libraries using libtool and the 'LTLIBRARIES' primary.

   Each '_LIBRARIES' variable is a list of the libraries to be built.
For instance, to create a library named 'libcpio.a', but not install it,
you would write:

     noinst_LIBRARIES = libcpio.a
     libcpio_a_SOURCES = ...

   The sources that go into a library are determined exactly as they are
for programs, via the '_SOURCES' variables.  Note that the library name
is canonicalized (*note Canonicalization::), so the '_SOURCES' variable
corresponding to 'libcpio.a' is 'libcpio_a_SOURCES', not
'libcpio.a_SOURCES'.

   Extra objects can be added to a library using the 'LIBRARY_LIBADD'
variable.  This should be used for objects determined by 'configure'.
Again from 'cpio':

     libcpio_a_LIBADD = $(LIBOBJS) $(ALLOCA)

   In addition, sources for extra objects that will not exist until
configure-time must be added to the 'BUILT_SOURCES' variable (*note
Sources::).

   Building a static library is done by compiling all object files, then
by invoking '$(AR) $(ARFLAGS)' followed by the name of the library and
the list of objects, and finally by calling '$(RANLIB)' on that library.
You should call 'AC_PROG_RANLIB' from your 'configure.ac' to define
'RANLIB' (Automake will complain otherwise).  You should also call
'AM_PROG_AR' to define 'AR', in order to support unusual archivers such
as Microsoft lib.  'ARFLAGS' will default to 'cru'; you can override
this variable by setting it in your 'Makefile.am' or by 'AC_SUBST'ing it
from your 'configure.ac'.  You can override the 'AR' variable by
defining a per-library 'maude_AR' variable (*note Program and Library
Variables::).

   Be careful when selecting library components conditionally.  Because
building an empty library is not portable, you should ensure that any
library always contains at least one object.

   To use a static library when building a program, add it to 'LDADD'
for this program.  In the following example, the program 'cpio' is
statically linked with the library 'libcpio.a'.

     noinst_LIBRARIES = libcpio.a
     libcpio_a_SOURCES = ...

     bin_PROGRAMS = cpio
     cpio_SOURCES = cpio.c ...
     cpio_LDADD = libcpio.a

8.3 Building a Shared Library
=============================

Building shared libraries portably is a relatively complex matter.  For
this reason, GNU Libtool (*note Introduction: (libtool)Top.) was created
to help build shared libraries in a platform-independent way.

8.3.1 The Libtool Concept
-------------------------

Libtool abstracts shared and static libraries into a unified concept
henceforth called "libtool libraries".  Libtool libraries are files
using the '.la' suffix, and can designate a static library, a shared
library, or maybe both.  Their exact nature cannot be determined until
'./configure' is run: not all platforms support all kinds of libraries,
and users can explicitly select which libraries should be built.
(However the package's maintainers can tune the default, *note The
'AC_PROG_LIBTOOL' macro: (libtool)AC_PROG_LIBTOOL.)

   Because object files for shared and static libraries must be compiled
differently, libtool is also used during compilation.  Object files
built by libtool are called "libtool objects": these are files using the
'.lo' suffix.  Libtool libraries are built from these libtool objects.

   You should not assume anything about the structure of '.la' or '.lo'
files and how libtool constructs them: this is libtool's concern, and
the last thing one wants is to learn about libtool's guts.  However the
existence of these files matters, because they are used as targets and
dependencies in 'Makefile's rules when building libtool libraries.
There are situations where you may have to refer to these, for instance
when expressing dependencies for building source files conditionally
(*note Conditional Libtool Sources::).

   People considering writing a plug-in system, with dynamically loaded
modules, should look into 'libltdl': libtool's dlopening library (*note
Using libltdl: (libtool)Using libltdl.).  This offers a portable
dlopening facility to load libtool libraries dynamically, and can also
achieve static linking where unavoidable.

   Before we discuss how to use libtool with Automake in details, it
should be noted that the libtool manual also has a section about how to
use Automake with libtool (*note Using Automake with Libtool:
(libtool)Using Automake.).

8.3.2 Building Libtool Libraries
--------------------------------

Automake uses libtool to build libraries declared with the 'LTLIBRARIES'
primary.  Each '_LTLIBRARIES' variable is a list of libtool libraries to
build.  For instance, to create a libtool library named 'libgettext.la',
and install it in 'libdir', write:

     lib_LTLIBRARIES = libgettext.la
     libgettext_la_SOURCES = gettext.c gettext.h ...

   Automake predefines the variable 'pkglibdir', so you can use
'pkglib_LTLIBRARIES' to install libraries in '$(libdir)/@PACKAGE@/'.

   If 'gettext.h' is a public header file that needs to be installed in
order for people to use the library, it should be declared using a
'_HEADERS' variable, not in 'libgettext_la_SOURCES'.  Headers listed in
the latter should be internal headers that are not part of the public
interface.

     lib_LTLIBRARIES = libgettext.la
     libgettext_la_SOURCES = gettext.c ...
     include_HEADERS = gettext.h ...

   A package can build and install such a library along with other
programs that use it.  This dependency should be specified using
'LDADD'.  The following example builds a program named 'hello' that is
linked with 'libgettext.la'.

     lib_LTLIBRARIES = libgettext.la
     libgettext_la_SOURCES = gettext.c ...

     bin_PROGRAMS = hello
     hello_SOURCES = hello.c ...
     hello_LDADD = libgettext.la

Whether 'hello' is statically or dynamically linked with 'libgettext.la'
is not yet known: this will depend on the configuration of libtool and
the capabilities of the host.

8.3.3 Building Libtool Libraries Conditionally
----------------------------------------------

Like conditional programs (*note Conditional Programs::), there are two
main ways to build conditional libraries: using Automake conditionals or
using Autoconf 'AC_SUBST'itutions.

   The important implementation detail you have to be aware of is that
the place where a library will be installed matters to libtool: it needs
to be indicated _at link-time_ using the '-rpath' option.

   For libraries whose destination directory is known when Automake
runs, Automake will automatically supply the appropriate '-rpath' option
to libtool.  This is the case for libraries listed explicitly in some
installable '_LTLIBRARIES' variables such as 'lib_LTLIBRARIES'.

   However, for libraries determined at configure time (and thus
mentioned in 'EXTRA_LTLIBRARIES'), Automake does not know the final
installation directory.  For such libraries you must add the '-rpath'
option to the appropriate '_LDFLAGS' variable by hand.

   The examples below illustrate the differences between these two
methods.

   Here is an example where 'WANTEDLIBS' is an 'AC_SUBST'ed variable set
at './configure'-time to either 'libfoo.la', 'libbar.la', both, or none.
Although '$(WANTEDLIBS)' appears in the 'lib_LTLIBRARIES', Automake
cannot guess it relates to 'libfoo.la' or 'libbar.la' at the time it
creates the link rule for these two libraries.  Therefore the '-rpath'
argument must be explicitly supplied.

     EXTRA_LTLIBRARIES = libfoo.la libbar.la
     lib_LTLIBRARIES = $(WANTEDLIBS)
     libfoo_la_SOURCES = foo.c ...
     libfoo_la_LDFLAGS = -rpath '$(libdir)'
     libbar_la_SOURCES = bar.c ...
     libbar_la_LDFLAGS = -rpath '$(libdir)'

   Here is how the same 'Makefile.am' would look using Automake
conditionals named 'WANT_LIBFOO' and 'WANT_LIBBAR'.  Now Automake is
able to compute the '-rpath' setting itself, because it's clear that
both libraries will end up in '$(libdir)' if they are installed.

     lib_LTLIBRARIES =
     if WANT_LIBFOO
     lib_LTLIBRARIES += libfoo.la
     endif
     if WANT_LIBBAR
     lib_LTLIBRARIES += libbar.la
     endif
     libfoo_la_SOURCES = foo.c ...
     libbar_la_SOURCES = bar.c ...

8.3.4 Libtool Libraries with Conditional Sources
------------------------------------------------

Conditional compilation of sources in a library can be achieved in the
same way as conditional compilation of sources in a program (*note
Conditional Sources::).  The only difference is that '_LIBADD' should be
used instead of '_LDADD' and that it should mention libtool objects
('.lo' files).

   So, to mimic the 'hello' example from *note Conditional Sources::, we
could build a 'libhello.la' library using either 'hello-linux.c' or
'hello-generic.c' with the following 'Makefile.am'.

     lib_LTLIBRARIES = libhello.la
     libhello_la_SOURCES = hello-common.c
     EXTRA_libhello_la_SOURCES = hello-linux.c hello-generic.c
     libhello_la_LIBADD = $(HELLO_SYSTEM)
     libhello_la_DEPENDENCIES = $(HELLO_SYSTEM)

And make sure 'configure' defines 'HELLO_SYSTEM' as either
'hello-linux.lo' or 'hello-generic.lo'.

   Or we could simply use an Automake conditional as follows.

     lib_LTLIBRARIES = libhello.la
     libhello_la_SOURCES = hello-common.c
     if LINUX
     libhello_la_SOURCES += hello-linux.c
     else
     libhello_la_SOURCES += hello-generic.c
     endif

8.3.5 Libtool Convenience Libraries
-----------------------------------

Sometimes you want to build libtool libraries that should not be
installed.  These are called "libtool convenience libraries" and are
typically used to encapsulate many sublibraries, later gathered into one
big installed library.

   Libtool convenience libraries are declared by directory-less
variables such as 'noinst_LTLIBRARIES', 'check_LTLIBRARIES', or even
'EXTRA_LTLIBRARIES'.  Unlike installed libtool libraries they do not
need an '-rpath' flag at link time (actually this is the only
difference).

   Convenience libraries listed in 'noinst_LTLIBRARIES' are always
built.  Those listed in 'check_LTLIBRARIES' are built only upon 'make
check'.  Finally, libraries listed in 'EXTRA_LTLIBRARIES' are never
built explicitly: Automake outputs rules to build them, but if the
library does not appear as a Makefile dependency anywhere it won't be
built (this is why 'EXTRA_LTLIBRARIES' is used for conditional
compilation).

   Here is a sample setup merging libtool convenience libraries from
subdirectories into one main 'libtop.la' library.

     # -- Top-level Makefile.am --
     SUBDIRS = sub1 sub2 ...
     lib_LTLIBRARIES = libtop.la
     libtop_la_SOURCES =
     libtop_la_LIBADD = 
       sub1/libsub1.la 
       sub2/libsub2.la 
       ...

     # -- sub1/Makefile.am --
     noinst_LTLIBRARIES = libsub1.la
     libsub1_la_SOURCES = ...

     # -- sub2/Makefile.am --
     # showing nested convenience libraries
     SUBDIRS = sub2.1 sub2.2 ...
     noinst_LTLIBRARIES = libsub2.la
     libsub2_la_SOURCES =
     libsub2_la_LIBADD = 
       sub21/libsub21.la 
       sub22/libsub22.la 
       ...

   When using such setup, beware that 'automake' will assume 'libtop.la'
is to be linked with the C linker.  This is because 'libtop_la_SOURCES'
is empty, so 'automake' picks C as default language.  If
'libtop_la_SOURCES' was not empty, 'automake' would select the linker as
explained in *note How the Linker is Chosen::.

   If one of the sublibraries contains non-C source, it is important
that the appropriate linker be chosen.  One way to achieve this is to
pretend that there is such a non-C file among the sources of the
library, thus forcing 'automake' to select the appropriate linker.  Here
is the top-level 'Makefile' of our example updated to force C++ linking.

     SUBDIRS = sub1 sub2 ...
     lib_LTLIBRARIES = libtop.la
     libtop_la_SOURCES =
     # Dummy C++ source to cause C++ linking.
     nodist_EXTRA_libtop_la_SOURCES = dummy.cxx
     libtop_la_LIBADD = 
       sub1/libsub1.la 
       sub2/libsub2.la 
       ...

   'EXTRA_*_SOURCES' variables are used to keep track of source files
that might be compiled (this is mostly useful when doing conditional
compilation using 'AC_SUBST', *note Conditional Libtool Sources::), and
the 'nodist_' prefix means the listed sources are not to be distributed
(*note Program and Library Variables::).  In effect the file 'dummy.cxx'
does not need to exist in the source tree.  Of course if you have some
real source file to list in 'libtop_la_SOURCES' there is no point in
cheating with 'nodist_EXTRA_libtop_la_SOURCES'.

8.3.6 Libtool Modules
---------------------

These are libtool libraries meant to be dlopened.  They are indicated to
libtool by passing '-module' at link-time.

     pkglib_LTLIBRARIES = mymodule.la
     mymodule_la_SOURCES = doit.c
     mymodule_la_LDFLAGS = -module

   Ordinarily, Automake requires that a library's name start with 'lib'.
However, when building a dynamically loadable module you might wish to
use a "nonstandard" name.  Automake will not complain about such
nonstandard names if it knows the library being built is a libtool
module, i.e., if '-module' explicitly appears in the library's
'_LDFLAGS' variable (or in the common 'AM_LDFLAGS' variable when no
per-library '_LDFLAGS' variable is defined).

   As always, 'AC_SUBST' variables are black boxes to Automake since
their values are not yet known when 'automake' is run.  Therefore if
'-module' is set via such a variable, Automake cannot notice it and will
proceed as if the library was an ordinary libtool library, with strict
naming.

   If 'mymodule_la_SOURCES' is not specified, then it defaults to the
single file 'mymodule.c' (*note Default _SOURCES::).

8.3.7 '_LIBADD', '_LDFLAGS', and '_LIBTOOLFLAGS'
------------------------------------------------

As shown in previous sections, the 'LIBRARY_LIBADD' variable should be
used to list extra libtool objects ('.lo' files) or libtool libraries
('.la') to add to LIBRARY.

   The 'LIBRARY_LDFLAGS' variable is the place to list additional
libtool linking flags, such as '-version-info', '-static', and a lot
more.  *Note Link mode: (libtool)Link mode.

   The 'libtool' command has two kinds of options: mode-specific options
and generic options.  Mode-specific options such as the aforementioned
linking flags should be lumped with the other flags passed to the tool
invoked by 'libtool' (hence the use of 'LIBRARY_LDFLAGS' for libtool
linking flags).  Generic options include '--tag=TAG' and '--silent'
(*note Invoking 'libtool': (libtool)Invoking libtool. for more options)
should appear before the mode selection on the command line; in
'Makefile.am's they should be listed in the 'LIBRARY_LIBTOOLFLAGS'
variable.

   If 'LIBRARY_LIBTOOLFLAGS' is not defined, then the variable
'AM_LIBTOOLFLAGS' is used instead.

   These flags are passed to libtool after the '--tag=TAG' option
computed by Automake (if any), so 'LIBRARY_LIBTOOLFLAGS' (or
'AM_LIBTOOLFLAGS') is a good place to override or supplement the
'--tag=TAG' setting.

   The libtool rules also use a 'LIBTOOLFLAGS' variable that should not
be set in 'Makefile.am': this is a user variable (*note Flag Variables
Ordering::.  It allows users to run 'make LIBTOOLFLAGS=--silent', for
instance.  Note that the verbosity of 'libtool' can also be influenced
by the Automake support for silent rules (*note Automake Silent
Rules::).

8.3.8 'LTLIBOBJS' and 'LTALLOCA'
--------------------------------

Where an ordinary library might include '$(LIBOBJS)' or '$(ALLOCA)'
(*note LIBOBJS::), a libtool library must use '$(LTLIBOBJS)' or
'$(LTALLOCA)'.  This is required because the object files that libtool
operates on do not necessarily end in '.o'.

   Nowadays, the computation of 'LTLIBOBJS' from 'LIBOBJS' is performed
automatically by Autoconf (*note 'AC_LIBOBJ' vs. 'LIBOBJS':
(autoconf)AC_LIBOBJ vs LIBOBJS.).

8.3.9 Common Issues Related to Libtool's Use
--------------------------------------------

8.3.9.1 Error: 'required file `./ltmain.sh' not found'
......................................................

Libtool comes with a tool called 'libtoolize' that will install
libtool's supporting files into a package.  Running this command will
install 'ltmain.sh'.  You should execute it before 'aclocal' and
'automake'.

   People upgrading old packages to newer autotools are likely to face
this issue because older Automake versions used to call 'libtoolize'.
Therefore old build scripts do not call 'libtoolize'.

   Since Automake 1.6, it has been decided that running 'libtoolize' was
none of Automake's business.  Instead, that functionality has been moved
into the 'autoreconf' command (*note Using 'autoreconf':
(autoconf)autoreconf Invocation.).  If you do not want to remember what
to run and when, just learn the 'autoreconf' command.  Hopefully,
replacing existing 'bootstrap.sh' or 'autogen.sh' scripts by a call to
'autoreconf' should also free you from any similar incompatible change
in the future.

8.3.9.2 Objects 'created with both libtool and without'
.......................................................

Sometimes, the same source file is used both to build a libtool library
and to build another non-libtool target (be it a program or another
library).

   Let's consider the following 'Makefile.am'.

     bin_PROGRAMS = prog
     prog_SOURCES = prog.c foo.c ...

     lib_LTLIBRARIES = libfoo.la
     libfoo_la_SOURCES = foo.c ...

(In this trivial case the issue could be avoided by linking 'libfoo.la'
with 'prog' instead of listing 'foo.c' in 'prog_SOURCES'.  But let's
assume we really want to keep 'prog' and 'libfoo.la' separate.)

   Technically, it means that we should build 'foo.$(OBJEXT)' for
'prog', and 'foo.lo' for 'libfoo.la'.  The problem is that in the course
of creating 'foo.lo', libtool may erase (or replace) 'foo.$(OBJEXT)',
and this cannot be avoided.

   Therefore, when Automake detects this situation it will complain with
a message such as
     object 'foo.$(OBJEXT)' created both with libtool and without

   A workaround for this issue is to ensure that these two objects get
different basenames.  As explained in *note Renamed Objects::, this
happens automatically when per-targets flags are used.

     bin_PROGRAMS = prog
     prog_SOURCES = prog.c foo.c ...
     prog_CFLAGS = $(AM_CFLAGS)

     lib_LTLIBRARIES = libfoo.la
     libfoo_la_SOURCES = foo.c ...

Adding 'prog_CFLAGS = $(AM_CFLAGS)' is almost a no-op, because when the
'prog_CFLAGS' is defined, it is used instead of 'AM_CFLAGS'.  However as
a side effect it will cause 'prog.c' and 'foo.c' to be compiled as
'prog-prog.$(OBJEXT)' and 'prog-foo.$(OBJEXT)', which solves the issue.

8.4 Program and Library Variables
=================================

Associated with each program is a collection of variables that can be
used to modify how that program is built.  There is a similar list of
such variables for each library.  The canonical name of the program (or
library) is used as a base for naming these variables.

   In the list below, we use the name "maude" to refer to the program or
library.  In your 'Makefile.am' you would replace this with the
canonical name of your program.  This list also refers to "maude" as a
program, but in general the same rules apply for both static and dynamic
libraries; the documentation below notes situations where programs and
libraries differ.

'maude_SOURCES'
     This variable, if it exists, lists all the source files that are
     compiled to build the program.  These files are added to the
     distribution by default.  When building the program, Automake will
     cause each source file to be compiled to a single '.o' file (or
     '.lo' when using libtool).  Normally these object files are named
     after the source file, but other factors can change this.  If a
     file in the '_SOURCES' variable has an unrecognized extension,
     Automake will do one of two things with it.  If a suffix rule
     exists for turning files with the unrecognized extension into '.o'
     files, then 'automake' will treat this file as it will any other
     source file (*note Support for Other Languages::).  Otherwise, the
     file will be ignored as though it were a header file.

     The prefixes 'dist_' and 'nodist_' can be used to control whether
     files listed in a '_SOURCES' variable are distributed.  'dist_' is
     redundant, as sources are distributed by default, but it can be
     specified for clarity if desired.

     It is possible to have both 'dist_' and 'nodist_' variants of a
     given '_SOURCES' variable at once; this lets you easily distribute
     some files and not others, for instance:

          nodist_maude_SOURCES = nodist.c
          dist_maude_SOURCES = dist-me.c

     By default the output file (on Unix systems, the '.o' file) will be
     put into the current build directory.  However, if the option
     'subdir-objects' is in effect in the current directory then the
     '.o' file will be put into the subdirectory named after the source
     file.  For instance, with 'subdir-objects' enabled,
     'sub/dir/file.c' will be compiled to 'sub/dir/file.o'.  Some people
     prefer this mode of operation.  You can specify 'subdir-objects' in
     'AUTOMAKE_OPTIONS' (*note Options::).

'EXTRA_maude_SOURCES'
     Automake needs to know the list of files you intend to compile
     _statically_.  For one thing, this is the only way Automake has of
     knowing what sort of language support a given 'Makefile.in'
     requires.  (1) This means that, for example, you can't put a
     configure substitution like '@my_sources@' into a '_SOURCES'
     variable.  If you intend to conditionally compile source files and
     use 'configure' to substitute the appropriate object names into,
     e.g., '_LDADD' (see below), then you should list the corresponding
     source files in the 'EXTRA_' variable.

     This variable also supports 'dist_' and 'nodist_' prefixes.  For
     instance, 'nodist_EXTRA_maude_SOURCES' would list extra sources
     that may need to be built, but should not be distributed.

'maude_AR'
     A static library is created by default by invoking '$(AR)
     $(ARFLAGS)' followed by the name of the library and then the
     objects being put into the library.  You can override this by
     setting the '_AR' variable.  This is usually used with C++; some
     C++ compilers require a special invocation in order to instantiate
     all the templates that should go into a library.  For instance, the
     SGI C++ compiler likes this variable set like so:
          libmaude_a_AR = $(CXX) -ar -o

'maude_LIBADD'
     Extra objects can be added to a _library_ using the '_LIBADD'
     variable.  For instance, this should be used for objects determined
     by 'configure' (*note A Library::).

     In the case of libtool libraries, 'maude_LIBADD' can also refer to
     other libtool libraries.

'maude_LDADD'
     Extra objects ('*.$(OBJEXT)') and libraries ('*.a', '*.la') can be
     added to a _program_ by listing them in the '_LDADD' variable.  For
     instance, this should be used for objects determined by 'configure'
     (*note Linking::).

     '_LDADD' and '_LIBADD' are inappropriate for passing
     program-specific linker flags (except for '-l', '-L', '-dlopen' and
     '-dlpreopen').  Use the '_LDFLAGS' variable for this purpose.

     For instance, if your 'configure.ac' uses 'AC_PATH_XTRA', you could
     link your program against the X libraries like so:

          maude_LDADD = $(X_PRE_LIBS) $(X_LIBS) $(X_EXTRA_LIBS)

     We recommend that you use '-l' and '-L' only when referring to
     third-party libraries, and give the explicit file names of any
     library built by your package.  Doing so will ensure that
     'maude_DEPENDENCIES' (see below) is correctly defined by default.

'maude_LDFLAGS'
     This variable is used to pass extra flags to the link step of a
     program or a shared library.  It overrides the 'AM_LDFLAGS'
     variable.

'maude_LIBTOOLFLAGS'
     This variable is used to pass extra options to 'libtool'.  It
     overrides the 'AM_LIBTOOLFLAGS' variable.  These options are output
     before 'libtool''s '--mode=MODE' option, so they should not be
     mode-specific options (those belong to the compiler or linker
     flags).  *Note Libtool Flags::.

'maude_DEPENDENCIES'
'EXTRA_maude_DEPENDENCIES'
     It is also occasionally useful to have a target (program or
     library) depend on some other file that is not actually part of
     that target.  This can be done using the '_DEPENDENCIES' variable.
     Each target depends on the contents of such a variable, but no
     further interpretation is done.

     Since these dependencies are associated to the link rule used to
     create the programs they should normally list files used by the
     link command.  That is '*.$(OBJEXT)', '*.a', or '*.la' files for
     programs; '*.lo' and '*.la' files for Libtool libraries; and
     '*.$(OBJEXT)' files for static libraries.  In rare cases you may
     need to add other kinds of files such as linker scripts, but
     _listing a source file in '_DEPENDENCIES' is wrong_.  If some
     source file needs to be built before all the components of a
     program are built, consider using the 'BUILT_SOURCES' variable
     (*note Sources::).

     If '_DEPENDENCIES' is not supplied, it is computed by Automake.
     The automatically-assigned value is the contents of '_LDADD' or
     '_LIBADD', with most configure substitutions, '-l', '-L', '-dlopen'
     and '-dlpreopen' options removed.  The configure substitutions that
     are left in are only '$(LIBOBJS)' and '$(ALLOCA)'; these are left
     because it is known that they will not cause an invalid value for
     '_DEPENDENCIES' to be generated.

     '_DEPENDENCIES' is more likely used to perform conditional
     compilation using an 'AC_SUBST' variable that contains a list of
     objects.  *Note Conditional Sources::, and *note Conditional
     Libtool Sources::.

     The 'EXTRA_*_DEPENDENCIES' variable may be useful for cases where
     you merely want to augment the 'automake'-generated '_DEPENDENCIES'
     variable rather than replacing it.

'maude_LINK'
     You can override the linker on a per-program basis.  By default the
     linker is chosen according to the languages used by the program.
     For instance, a program that includes C++ source code would use the
     C++ compiler to link.  The '_LINK' variable must hold the name of a
     command that can be passed all the '.o' file names and libraries to
     link against as arguments.  Note that the name of the underlying
     program is _not_ passed to '_LINK'; typically one uses '$@':

          maude_LINK = $(CCLD) -magic -o $@

     If a '_LINK' variable is not supplied, it may still be generated
     and used by Automake due to the use of per-target link flags such
     as '_CFLAGS', '_LDFLAGS' or '_LIBTOOLFLAGS', in cases where they
     apply.

'maude_CCASFLAGS'
'maude_CFLAGS'
'maude_CPPFLAGS'
'maude_CXXFLAGS'
'maude_FFLAGS'
'maude_GCJFLAGS'
'maude_LFLAGS'
'maude_OBJCFLAGS'
'maude_OBJCXXFLAGS'
'maude_RFLAGS'
'maude_UPCFLAGS'
'maude_YFLAGS'
     Automake allows you to set compilation flags on a per-program (or
     per-library) basis.  A single source file can be included in
     several programs, and it will potentially be compiled with
     different flags for each program.  This works for any language
     directly supported by Automake.  These "per-target compilation
     flags" are '_CCASFLAGS', '_CFLAGS', '_CPPFLAGS', '_CXXFLAGS',
     '_FFLAGS', '_GCJFLAGS', '_LFLAGS', '_OBJCFLAGS', '_OBJCXXFLAGS',
     '_RFLAGS', '_UPCFLAGS', and '_YFLAGS'.

     When using a per-target compilation flag, Automake will choose a
     different name for the intermediate object files.  Ordinarily a
     file like 'sample.c' will be compiled to produce 'sample.o'.
     However, if the program's '_CFLAGS' variable is set, then the
     object file will be named, for instance, 'maude-sample.o'.  (See
     also *note Renamed Objects::).

     In compilations with per-target flags, the ordinary 'AM_' form of
     the flags variable is _not_ automatically included in the
     compilation (however, the user form of the variable _is_ included).
     So for instance, if you want the hypothetical 'maude' compilations
     to also use the value of 'AM_CFLAGS', you would need to write:

          maude_CFLAGS = ... your flags ... $(AM_CFLAGS)

     *Note Flag Variables Ordering::, for more discussion about the
     interaction between user variables, 'AM_' shadow variables, and
     per-target variables.

'maude_SHORTNAME'
     On some platforms the allowable file names are very short.  In
     order to support these systems and per-target compilation flags at
     the same time, Automake allows you to set a "short name" that will
     influence how intermediate object files are named.  For instance,
     in the following example,

          bin_PROGRAMS = maude
          maude_CPPFLAGS = -DSOMEFLAG
          maude_SHORTNAME = m
          maude_SOURCES = sample.c ...

     the object file would be named 'm-sample.o' rather than
     'maude-sample.o'.

     This facility is rarely needed in practice, and we recommend
     avoiding it until you find it is required.

   ---------- Footnotes ----------

   (1) There are other, more obscure reasons for this limitation as
well.

8.5 Default '_SOURCES'
======================

'_SOURCES' variables are used to specify source files of programs (*note
A Program::), libraries (*note A Library::), and Libtool libraries
(*note A Shared Library::).

   When no such variable is specified for a target, Automake will define
one itself.  The default is to compile a single C file whose base name
is the name of the target itself, with any extension replaced by
'AM_DEFAULT_SOURCE_EXT', which defaults to '.c'.

   For example if you have the following somewhere in your 'Makefile.am'
with no corresponding 'libfoo_a_SOURCES':

     lib_LIBRARIES = libfoo.a sub/libc++.a

'libfoo.a' will be built using a default source file named 'libfoo.c',
and 'sub/libc++.a' will be built from 'sub/libc++.c'.  (In older
versions 'sub/libc++.a' would be built from 'sub_libc___a.c', i.e., the
default source was the canonized name of the target, with '.c' appended.
We believe the new behavior is more sensible, but for backward
compatibility 'automake' will use the old name if a file or a rule with
that name exists and 'AM_DEFAULT_SOURCE_EXT' is not used.)

   Default sources are mainly useful in test suites, when building many
test programs each from a single source.  For instance, in

     check_PROGRAMS = test1 test2 test3
     AM_DEFAULT_SOURCE_EXT = .cpp

'test1', 'test2', and 'test3' will be built from 'test1.cpp',
'test2.cpp', and 'test3.cpp'.  Without the last line, they will be built
from 'test1.c', 'test2.c', and 'test3.c'.

   Another case where this is convenient is building many Libtool
modules ('moduleN.la'), each defined in its own file ('moduleN.c').

     AM_LDFLAGS = -module
     lib_LTLIBRARIES = module1.la module2.la module3.la

   Finally, there is one situation where this default source computation
needs to be avoided: when a target should not be built from sources.  We
already saw such an example in *note true::; this happens when all the
constituents of a target have already been compiled and just need to be
combined using a '_LDADD' variable.  Then it is necessary to define an
empty '_SOURCES' variable, so that 'automake' does not compute a
default.

     bin_PROGRAMS = target
     target_SOURCES =
     target_LDADD = libmain.a libmisc.a

8.6 Special handling for 'LIBOBJS' and 'ALLOCA'
===============================================

The '$(LIBOBJS)' and '$(ALLOCA)' variables list object files that should
be compiled into the project to provide an implementation for functions
that are missing or broken on the host system.  They are substituted by
'configure'.

   These variables are defined by Autoconf macros such as 'AC_LIBOBJ',
'AC_REPLACE_FUNCS' (*note Generic Function Checks: (autoconf)Generic
Functions.), or 'AC_FUNC_ALLOCA' (*note Particular Function Checks:
(autoconf)Particular Functions.).  Many other Autoconf macros call
'AC_LIBOBJ' or 'AC_REPLACE_FUNCS' to populate '$(LIBOBJS)'.

   Using these variables is very similar to doing conditional
compilation using 'AC_SUBST' variables, as described in *note
Conditional Sources::.  That is, when building a program, '$(LIBOBJS)'
and '$(ALLOCA)' should be added to the associated '*_LDADD' variable, or
to the '*_LIBADD' variable when building a library.  However there is no
need to list the corresponding sources in 'EXTRA_*_SOURCES' nor to
define '*_DEPENDENCIES'.  Automake automatically adds '$(LIBOBJS)' and
'$(ALLOCA)' to the dependencies, and it will discover the list of
corresponding source files automatically (by tracing the invocations of
the 'AC_LIBSOURCE' Autoconf macros).  If you have already defined
'*_DEPENDENCIES' explicitly for an unrelated reason, then you either
need to add these variables manually, or use 'EXTRA_*_DEPENDENCIES'
instead of '*_DEPENDENCIES'.

   These variables are usually used to build a portability library that
is linked with all the programs of the project.  We now review a sample
setup.  First, 'configure.ac' contains some checks that affect either
'LIBOBJS' or 'ALLOCA'.

     # configure.ac
     ...
     AC_CONFIG_LIBOBJ_DIR([lib])
     ...
     AC_FUNC_MALLOC             dnl May add malloc.$(OBJEXT) to LIBOBJS
     AC_FUNC_MEMCMP             dnl May add memcmp.$(OBJEXT) to LIBOBJS
     AC_REPLACE_FUNCS([strdup]) dnl May add strdup.$(OBJEXT) to LIBOBJS
     AC_FUNC_ALLOCA             dnl May add alloca.$(OBJEXT) to ALLOCA
     ...
     AC_CONFIG_FILES([
       lib/Makefile
       src/Makefile
     ])
     AC_OUTPUT

   The 'AC_CONFIG_LIBOBJ_DIR' tells Autoconf that the source files of
these object files are to be found in the 'lib/' directory.  Automake
can also use this information, otherwise it expects the source files are
to be in the directory where the '$(LIBOBJS)' and '$(ALLOCA)' variables
are used.

   The 'lib/' directory should therefore contain 'malloc.c', 'memcmp.c',
'strdup.c', 'alloca.c'.  Here is its 'Makefile.am':

     # lib/Makefile.am

     noinst_LIBRARIES = libcompat.a
     libcompat_a_SOURCES =
     libcompat_a_LIBADD = $(LIBOBJS) $(ALLOCA)

   The library can have any name, of course, and anyway it is not going
to be installed: it just holds the replacement versions of the missing
or broken functions so we can later link them in.  Many projects also
include extra functions, specific to the project, in that library: they
are simply added on the '_SOURCES' line.

   There is a small trap here, though: '$(LIBOBJS)' and '$(ALLOCA)'
might be empty, and building an empty library is not portable.  You
should ensure that there is always something to put in 'libcompat.a'.
Most projects will also add some utility functions in that directory,
and list them in 'libcompat_a_SOURCES', so in practice 'libcompat.a'
cannot be empty.

   Finally here is how this library could be used from the 'src/'
directory.

     # src/Makefile.am

     # Link all programs in this directory with libcompat.a
     LDADD = ../lib/libcompat.a

     bin_PROGRAMS = tool1 tool2 ...
     tool1_SOURCES = ...
     tool2_SOURCES = ...

   When option 'subdir-objects' is not used, as in the above example,
the variables '$(LIBOBJS)' or '$(ALLOCA)' can only be used in the
directory where their sources lie.  E.g., here it would be wrong to use
'$(LIBOBJS)' or '$(ALLOCA)' in 'src/Makefile.am'.  However if both
'subdir-objects' and 'AC_CONFIG_LIBOBJ_DIR' are used, it is OK to use
these variables in other directories.  For instance 'src/Makefile.am'
could be changed as follows.

     # src/Makefile.am

     AUTOMAKE_OPTIONS = subdir-objects
     LDADD = $(LIBOBJS) $(ALLOCA)

     bin_PROGRAMS = tool1 tool2 ...
     tool1_SOURCES = ...
     tool2_SOURCES = ...

   Because '$(LIBOBJS)' and '$(ALLOCA)' contain object file names that
end with '.$(OBJEXT)', they are not suitable for Libtool libraries
(where the expected object extension is '.lo'): 'LTLIBOBJS' and
'LTALLOCA' should be used instead.

   'LTLIBOBJS' is defined automatically by Autoconf and should not be
defined by hand (as in the past), however at the time of writing
'LTALLOCA' still needs to be defined from 'ALLOCA' manually.  *Note
'AC_LIBOBJ' vs. 'LIBOBJS': (autoconf)AC_LIBOBJ vs LIBOBJS.

8.7 Variables used when building a program
==========================================

Occasionally it is useful to know which 'Makefile' variables Automake
uses for compilations, and in which order (*note Flag Variables
Ordering::); for instance, you might need to do your own compilation in
some special cases.

   Some variables are inherited from Autoconf; these are 'CC', 'CFLAGS',
'CPPFLAGS', 'DEFS', 'LDFLAGS', and 'LIBS'.

   There are some additional variables that Automake defines on its own:

'AM_CPPFLAGS'
     The contents of this variable are passed to every compilation that
     invokes the C preprocessor; it is a list of arguments to the
     preprocessor.  For instance, '-I' and '-D' options should be listed
     here.

     Automake already provides some '-I' options automatically, in a
     separate variable that is also passed to every compilation that
     invokes the C preprocessor.  In particular it generates '-I.',
     '-I$(srcdir)', and a '-I' pointing to the directory holding
     'config.h' (if you've used 'AC_CONFIG_HEADERS').  You can disable
     the default '-I' options using the 'nostdinc' option.

     When a file to be included is generated during the build and not
     part of a distribution tarball, its location is under
     '$(builddir)', not under '$(srcdir)'.  This matters especially for
     packages that use header files placed in sub-directories and want
     to allow builds outside the source tree (*note VPATH Builds::).  In
     that case we recommend to use a pair of '-I' options, such as,
     e.g., '-Isome/subdir -I$(srcdir)/some/subdir' or
     '-I$(top_builddir)/some/subdir -I$(top_srcdir)/some/subdir'.  Note
     that the reference to the build tree should come before the
     reference to the source tree, so that accidentally leftover
     generated files in the source directory are ignored.

     'AM_CPPFLAGS' is ignored in preference to a per-executable (or
     per-library) '_CPPFLAGS' variable if it is defined.

'INCLUDES'
     This does the same job as 'AM_CPPFLAGS' (or any per-target
     '_CPPFLAGS' variable if it is used).  It is an older name for the
     same functionality.  This variable is deprecated; we suggest using
     'AM_CPPFLAGS' and per-target '_CPPFLAGS' instead.

'AM_CFLAGS'
     This is the variable the 'Makefile.am' author can use to pass in
     additional C compiler flags.  In some situations, this is not used,
     in preference to the per-executable (or per-library) '_CFLAGS'.

'COMPILE'
     This is the command used to actually compile a C source file.  The
     file name is appended to form the complete command line.

'AM_LDFLAGS'
     This is the variable the 'Makefile.am' author can use to pass in
     additional linker flags.  In some situations, this is not used, in
     preference to the per-executable (or per-library) '_LDFLAGS'.

'LINK'
     This is the command used to actually link a C program.  It already
     includes '-o $@' and the usual variable references (for instance,
     'CFLAGS'); it takes as "arguments" the names of the object files
     and libraries to link in.  This variable is not used when the
     linker is overridden with a per-target '_LINK' variable or
     per-target flags cause Automake to define such a '_LINK' variable.

8.8 Yacc and Lex support
========================

Automake has somewhat idiosyncratic support for Yacc and Lex.

   Automake assumes that the '.c' file generated by 'yacc' (or 'lex')
should be named using the basename of the input file.  That is, for a
yacc source file 'foo.y', Automake will cause the intermediate file to
be named 'foo.c' (as opposed to 'y.tab.c', which is more traditional).

   The extension of a yacc source file is used to determine the
extension of the resulting C or C++ source and header files.  Note that
header files are generated only when the '-d' Yacc option is used; see
below for more information about this flag, and how to specify it.
Files with the extension '.y' will thus be turned into '.c' sources and
'.h' headers; likewise, '.yy' will become '.cc' and '.hh', '.y++' will
become 'c++' and 'h++', '.yxx' will become '.cxx' and '.hxx', and '.ypp'
will become '.cpp' and '.hpp'.

   Similarly, lex source files can be used to generate C or C++; the
extensions '.l', '.ll', '.l++', '.lxx', and '.lpp' are recognized.

   You should never explicitly mention the intermediate (C or C++) file
in any 'SOURCES' variable; only list the source file.

   The intermediate files generated by 'yacc' (or 'lex') will be
included in any distribution that is made.  That way the user doesn't
need to have 'yacc' or 'lex'.

   If a 'yacc' source file is seen, then your 'configure.ac' must define
the variable 'YACC'.  This is most easily done by invoking the macro
'AC_PROG_YACC' (*note Particular Program Checks: (autoconf)Particular
Programs.).

   When 'yacc' is invoked, it is passed 'AM_YFLAGS' and 'YFLAGS'.  The
latter is a user variable and the former is intended for the
'Makefile.am' author.

   'AM_YFLAGS' is usually used to pass the '-d' option to 'yacc'.
Automake knows what this means and will automatically adjust its rules
to update and distribute the header file built by 'yacc -d'(1).  What
Automake cannot guess, though, is where this header will be used: it is
up to you to ensure the header gets built before it is first used.
Typically this is necessary in order for dependency tracking to work
when the header is included by another file.  The common solution is
listing the header file in 'BUILT_SOURCES' (*note Sources::) as follows.

     BUILT_SOURCES = parser.h
     AM_YFLAGS = -d
     bin_PROGRAMS = foo
     foo_SOURCES = ... parser.y ...

   If a 'lex' source file is seen, then your 'configure.ac' must define
the variable 'LEX'.  You can use 'AC_PROG_LEX' to do this (*note
Particular Program Checks: (autoconf)Particular Programs.), but using
'AM_PROG_LEX' macro (*note Macros::) is recommended.

   When 'lex' is invoked, it is passed 'AM_LFLAGS' and 'LFLAGS'.  The
latter is a user variable and the former is intended for the
'Makefile.am' author.

   When 'AM_MAINTAINER_MODE' (*note maintainer-mode::) is used, the
rebuild rule for distributed Yacc and Lex sources are only used when
'maintainer-mode' is enabled, or when the files have been erased.

   When 'lex' or 'yacc' sources are used, 'automake -a' automatically
installs an auxiliary program called 'ylwrap' in your package (*note
Auxiliary Programs::).  This program is used by the build rules to
rename the output of these tools, and makes it possible to include
multiple 'yacc' (or 'lex') source files in a single directory.  (This is
necessary because yacc's output file name is fixed, and a parallel make
could conceivably invoke more than one instance of 'yacc'
simultaneously.)

   For 'yacc', simply managing locking is insufficient.  The output of
'yacc' always uses the same symbol names internally, so it isn't
possible to link two 'yacc' parsers into the same executable.

   We recommend using the following renaming hack used in 'gdb':
     #define yymaxdepth c_maxdepth
     #define yyparse c_parse
     #define yylex   c_lex
     #define yyerror c_error
     #define yylval  c_lval
     #define yychar  c_char
     #define yydebug c_debug
     #define yypact  c_pact
     #define yyr1    c_r1
     #define yyr2    c_r2
     #define yydef   c_def
     #define yychk   c_chk
     #define yypgo   c_pgo
     #define yyact   c_act
     #define yyexca  c_exca
     #define yyerrflag c_errflag
     #define yynerrs c_nerrs
     #define yyps    c_ps
     #define yypv    c_pv
     #define yys     c_s
     #define yy_yys  c_yys
     #define yystate c_state
     #define yytmp   c_tmp
     #define yyv     c_v
     #define yy_yyv  c_yyv
     #define yyval   c_val
     #define yylloc  c_lloc
     #define yyreds  c_reds
     #define yytoks  c_toks
     #define yylhs   c_yylhs
     #define yylen   c_yylen
     #define yydefred c_yydefred
     #define yydgoto  c_yydgoto
     #define yysindex c_yysindex
     #define yyrindex c_yyrindex
     #define yygindex c_yygindex
     #define yytable  c_yytable
     #define yycheck  c_yycheck
     #define yyname   c_yyname
     #define yyrule   c_yyrule

   For each define, replace the 'c_' prefix with whatever you like.
These defines work for 'bison', 'byacc', and traditional 'yacc's.  If
you find a parser generator that uses a symbol not covered here, please
report the new name so it can be added to the list.

   ---------- Footnotes ----------

   (1) Please note that 'automake' recognizes '-d' in 'AM_YFLAGS' only
if it is not clustered with other options; for example, it won't be
recognized if 'AM_YFLAGS' is '-dt', but it will be if 'AM_YFLAGS' is '-d
-t' or '-t -d'.

8.9 C++ Support
===============

Automake includes full support for C++.

   Any package including C++ code must define the output variable 'CXX'
in 'configure.ac'; the simplest way to do this is to use the
'AC_PROG_CXX' macro (*note Particular Program Checks:
(autoconf)Particular Programs.).

   A few additional variables are defined when a C++ source file is
seen:

'CXX'
     The name of the C++ compiler.

'CXXFLAGS'
     Any flags to pass to the C++ compiler.

'AM_CXXFLAGS'
     The maintainer's variant of 'CXXFLAGS'.

'CXXCOMPILE'
     The command used to actually compile a C++ source file.  The file
     name is appended to form the complete command line.

'CXXLINK'
     The command used to actually link a C++ program.

8.10 Objective C Support
========================

Automake includes some support for Objective C.

   Any package including Objective C code must define the output
variable 'OBJC' in 'configure.ac'; the simplest way to do this is to use
the 'AC_PROG_OBJC' macro (*note Particular Program Checks:
(autoconf)Particular Programs.).

   A few additional variables are defined when an Objective C source
file is seen:

'OBJC'
     The name of the Objective C compiler.

'OBJCFLAGS'
     Any flags to pass to the Objective C compiler.

'AM_OBJCFLAGS'
     The maintainer's variant of 'OBJCFLAGS'.

'OBJCCOMPILE'
     The command used to actually compile an Objective C source file.
     The file name is appended to form the complete command line.

'OBJCLINK'
     The command used to actually link an Objective C program.

8.11 Objective C++ Support
==========================

Automake includes some support for Objective C++.

   Any package including Objective C++ code must define the output
variable 'OBJCXX' in 'configure.ac'; the simplest way to do this is to
use the 'AC_PROG_OBJCXX' macro (*note Particular Program Checks:
(autoconf)Particular Programs.).

   A few additional variables are defined when an Objective C++ source
file is seen:

'OBJCXX'
     The name of the Objective C++ compiler.

'OBJCXXFLAGS'
     Any flags to pass to the Objective C++ compiler.

'AM_OBJCXXFLAGS'
     The maintainer's variant of 'OBJCXXFLAGS'.

'OBJCXXCOMPILE'
     The command used to actually compile an Objective C++ source file.
     The file name is appended to form the complete command line.

'OBJCXXLINK'
     The command used to actually link an Objective C++ program.

8.12 Unified Parallel C Support
===============================

Automake includes some support for Unified Parallel C.

   Any package including Unified Parallel C code must define the output
variable 'UPC' in 'configure.ac'; the simplest way to do this is to use
the 'AM_PROG_UPC' macro (*note Public Macros::).

   A few additional variables are defined when a Unified Parallel C
source file is seen:

'UPC'
     The name of the Unified Parallel C compiler.

'UPCFLAGS'
     Any flags to pass to the Unified Parallel C compiler.

'AM_UPCFLAGS'
     The maintainer's variant of 'UPCFLAGS'.

'UPCCOMPILE'
     The command used to actually compile a Unified Parallel C source
     file.  The file name is appended to form the complete command line.

'UPCLINK'
     The command used to actually link a Unified Parallel C program.

8.13 Assembly Support
=====================

Automake includes some support for assembly code.  There are two forms
of assembler files: normal ('*.s') and preprocessed by 'CPP' ('*.S' or
'*.sx').

   The variable 'CCAS' holds the name of the compiler used to build
assembly code.  This compiler must work a bit like a C compiler; in
particular it must accept '-c' and '-o'.  The values of 'CCASFLAGS' and
'AM_CCASFLAGS' (or its per-target definition) is passed to the
compilation.  For preprocessed files, 'DEFS', 'DEFAULT_INCLUDES',
'INCLUDES', 'CPPFLAGS' and 'AM_CPPFLAGS' are also used.

   The autoconf macro 'AM_PROG_AS' will define 'CCAS' and 'CCASFLAGS'
for you (unless they are already set, it simply sets 'CCAS' to the C
compiler and 'CCASFLAGS' to the C compiler flags), but you are free to
define these variables by other means.

   Only the suffixes '.s', '.S', and '.sx' are recognized by 'automake'
as being files containing assembly code.

8.14 Fortran 77 Support
=======================

Automake includes full support for Fortran 77.

   Any package including Fortran 77 code must define the output variable
'F77' in 'configure.ac'; the simplest way to do this is to use the
'AC_PROG_F77' macro (*note Particular Program Checks:
(autoconf)Particular Programs.).

   A few additional variables are defined when a Fortran 77 source file
is seen:

'F77'
     The name of the Fortran 77 compiler.

'FFLAGS'
     Any flags to pass to the Fortran 77 compiler.

'AM_FFLAGS'
     The maintainer's variant of 'FFLAGS'.

'RFLAGS'
     Any flags to pass to the Ratfor compiler.

'AM_RFLAGS'
     The maintainer's variant of 'RFLAGS'.

'F77COMPILE'
     The command used to actually compile a Fortran 77 source file.  The
     file name is appended to form the complete command line.

'FLINK'
     The command used to actually link a pure Fortran 77 program or
     shared library.

   Automake can handle preprocessing Fortran 77 and Ratfor source files
in addition to compiling them(1).  Automake also contains some support
for creating programs and shared libraries that are a mixture of Fortran
77 and other languages (*note Mixing Fortran 77 With C and C++::).

   These issues are covered in the following sections.

   ---------- Footnotes ----------

   (1) Much, if not most, of the information in the following sections
pertaining to preprocessing Fortran 77 programs was taken almost
verbatim from *note Catalogue of Rules: (make)Catalogue of Rules.

8.14.1 Preprocessing Fortran 77
-------------------------------

'N.f' is made automatically from 'N.F' or 'N.r'.  This rule runs just
the preprocessor to convert a preprocessable Fortran 77 or Ratfor source
file into a strict Fortran 77 source file.  The precise command used is
as follows:

'.F'
     '$(F77) -F $(DEFS) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS)
     $(AM_FFLAGS) $(FFLAGS)'

'.r'
     '$(F77) -F $(AM_FFLAGS) $(FFLAGS) $(AM_RFLAGS) $(RFLAGS)'

8.14.2 Compiling Fortran 77 Files
---------------------------------

'N.o' is made automatically from 'N.f', 'N.F' or 'N.r' by running the
Fortran 77 compiler.  The precise command used is as follows:

'.f'
     '$(F77) -c $(AM_FFLAGS) $(FFLAGS)'

'.F'
     '$(F77) -c $(DEFS) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS)
     $(AM_FFLAGS) $(FFLAGS)'

'.r'
     '$(F77) -c $(AM_FFLAGS) $(FFLAGS) $(AM_RFLAGS) $(RFLAGS)'

8.14.3 Mixing Fortran 77 With C and C++
---------------------------------------

Automake currently provides _limited_ support for creating programs and
shared libraries that are a mixture of Fortran 77 and C and/or C++.
However, there are many other issues related to mixing Fortran 77 with
other languages that are _not_ (currently) handled by Automake, but that
are handled by other packages(1).

   Automake can help in two ways:

  1. Automatic selection of the linker depending on which combinations
     of source code.

  2. Automatic selection of the appropriate linker flags (e.g., '-L' and
     '-l') to pass to the automatically selected linker in order to link
     in the appropriate Fortran 77 intrinsic and run-time libraries.

     These extra Fortran 77 linker flags are supplied in the output
     variable 'FLIBS' by the 'AC_F77_LIBRARY_LDFLAGS' Autoconf macro.
     *Note Fortran Compiler Characteristics: (autoconf)Fortran Compiler.

   If Automake detects that a program or shared library (as mentioned in
some '_PROGRAMS' or '_LTLIBRARIES' primary) contains source code that is
a mixture of Fortran 77 and C and/or C++, then it requires that the
macro 'AC_F77_LIBRARY_LDFLAGS' be called in 'configure.ac', and that
either '$(FLIBS)' appear in the appropriate '_LDADD' (for programs) or
'_LIBADD' (for shared libraries) variables.  It is the responsibility of
the person writing the 'Makefile.am' to make sure that '$(FLIBS)'
appears in the appropriate '_LDADD' or '_LIBADD' variable.

   For example, consider the following 'Makefile.am':

     bin_PROGRAMS = foo
     foo_SOURCES  = main.cc foo.f
     foo_LDADD    = libfoo.la $(FLIBS)

     pkglib_LTLIBRARIES = libfoo.la
     libfoo_la_SOURCES  = bar.f baz.c zardoz.cc
     libfoo_la_LIBADD   = $(FLIBS)

   In this case, Automake will insist that 'AC_F77_LIBRARY_LDFLAGS' is
mentioned in 'configure.ac'.  Also, if '$(FLIBS)' hadn't been mentioned
in 'foo_LDADD' and 'libfoo_la_LIBADD', then Automake would have issued a
warning.

   ---------- Footnotes ----------

   (1) For example, the cfortran package
(http://www-zeus.desy.de/~burow/cfortran/) addresses all of these
inter-language issues, and runs under nearly all Fortran 77, C and C++
compilers on nearly all platforms.  However, 'cfortran' is not yet Free
Software, but it will be in the next major release.

8.14.3.1 How the Linker is Chosen
.................................

When a program or library mixes several languages, Automake choose the
linker according to the following priorities.  (The names in parentheses
are the variables containing the link command.)

  1. Native Java ('GCJLINK')
  2. Objective C++ ('OBJCXXLINK')
  3. C++ ('CXXLINK')
  4. Fortran 77 ('F77LINK')
  5. Fortran ('FCLINK')
  6. Objective C ('OBJCLINK')
  7. Unified Parallel C ('UPCLINK')
  8. C ('LINK')

   For example, if Fortran 77, C and C++ source code is compiled into a
program, then the C++ linker will be used.  In this case, if the C or
Fortran 77 linkers required any special libraries that weren't included
by the C++ linker, then they must be manually added to an '_LDADD' or
'_LIBADD' variable by the user writing the 'Makefile.am'.

   Automake only looks at the file names listed in '_SOURCES' variables
to choose the linker, and defaults to the C linker.  Sometimes this is
inconvenient because you are linking against a library written in
another language and would like to set the linker more appropriately.
*Note Libtool Convenience Libraries::, for a trick with
'nodist_EXTRA_..._SOURCES'.

   A per-target '_LINK' variable will override the above selection.
Per-target link flags will cause Automake to write a per-target '_LINK'
variable according to the language chosen as above.

8.15 Fortran 9x Support
=======================

Automake includes support for Fortran 9x.

   Any package including Fortran 9x code must define the output variable
'FC' in 'configure.ac'; the simplest way to do this is to use the
'AC_PROG_FC' macro (*note Particular Program Checks:
(autoconf)Particular Programs.).

   A few additional variables are defined when a Fortran 9x source file
is seen:

'FC'
     The name of the Fortran 9x compiler.

'FCFLAGS'
     Any flags to pass to the Fortran 9x compiler.

'AM_FCFLAGS'
     The maintainer's variant of 'FCFLAGS'.

'FCCOMPILE'
     The command used to actually compile a Fortran 9x source file.  The
     file name is appended to form the complete command line.

'FCLINK'
     The command used to actually link a pure Fortran 9x program or
     shared library.

8.15.1 Compiling Fortran 9x Files
---------------------------------

'FILE.o' is made automatically from 'FILE.f90', 'FILE.f95', 'FILE.f03',
or 'FILE.f08' by running the Fortran 9x compiler.  The precise command
used is as follows:

'.f90'
     '$(FC) $(AM_FCFLAGS) $(FCFLAGS) -c $(FCFLAGS_f90) $<'

'.f95'
     '$(FC) $(AM_FCFLAGS) $(FCFLAGS) -c $(FCFLAGS_f95) $<'

'.f03'
     '$(FC) $(AM_FCFLAGS) $(FCFLAGS) -c $(FCFLAGS_f03) $<'

'.f08'
     '$(FC) $(AM_FCFLAGS) $(FCFLAGS) -c $(FCFLAGS_f08) $<'

8.16 Compiling Java sources using gcj
=====================================

Automake includes support for natively compiled Java, using 'gcj', the
Java front end to the GNU Compiler Collection (rudimentary support for
compiling Java to bytecode using the 'javac' compiler is also present,
_albeit deprecated_; *note Java::).

   Any package including Java code to be compiled must define the output
variable 'GCJ' in 'configure.ac'; the variable 'GCJFLAGS' must also be
defined somehow (either in 'configure.ac' or 'Makefile.am').  The
simplest way to do this is to use the 'AM_PROG_GCJ' macro.

   By default, programs including Java source files are linked with
'gcj'.

   As always, the contents of 'AM_GCJFLAGS' are passed to every
compilation invoking 'gcj' (in its role as an ahead-of-time compiler,
when invoking it to create '.class' files, 'AM_JAVACFLAGS' is used
instead).  If it is necessary to pass options to 'gcj' from
'Makefile.am', this variable, and not the user variable 'GCJFLAGS',
should be used.

   'gcj' can be used to compile '.java', '.class', '.zip', or '.jar'
files.

   When linking, 'gcj' requires that the main class be specified using
the '--main=' option.  The easiest way to do this is to use the
'_LDFLAGS' variable for the program.

8.17 Vala Support
=================

Automake provides initial support for Vala
(<http://www.vala-project.org/>).  This requires valac version 0.7.0 or
later, and currently requires the user to use GNU 'make'.

     foo_SOURCES = foo.vala bar.vala zardoc.c

   Any '.vala' file listed in a '_SOURCES' variable will be compiled
into C code by the Vala compiler.  The generated '.c' files are
distributed.  The end user does not need to have a Vala compiler
installed.

   Automake ships with an Autoconf macro called 'AM_PROG_VALAC' that
will locate the Vala compiler and optionally check its version number.

 -- Macro: AM_PROG_VALAC ([MINIMUM-VERSION], [ACTION-IF-FOUND],
     [ACTION-IF-NOT-FOUND]) Search for a Vala compiler in 'PATH'.  If it
     is found, the variable 'VALAC' is set to point to it (see below for
     more details).  This macro takes three optional arguments.  The
     first argument, if present, is the minimum version of the Vala
     compiler required to compile this package.  If a compiler is found
     and satisfies MINIMUM-VERSION, then ACTION-IF-FOUND is run (this
     defaults to do nothing).  Otherwise, ACTION-IF-NOT-FOUND is run.
     If ACTION-IF-NOT-FOUND is not specified, the default value is to
     print a warning in case no compiler is found, or if a too-old
     version of the compiler is found.

   There are a few variables that are used when compiling Vala sources:

'VALAC'
     Absolute path to the Vala compiler, or simply 'valac' if no
     suitable compiler Vala could be found at configure runtime.

'VALAFLAGS'
     Additional arguments for the Vala compiler.

'AM_VALAFLAGS'
     The maintainer's variant of 'VALAFLAGS'.

          lib_LTLIBRARIES = libfoo.la
          libfoo_la_SOURCES = foo.vala

   Note that currently, you cannot use per-target '*_VALAFLAGS' (*note
Renamed Objects::) to produce different C files from one Vala source
file.

8.18 Support for Other Languages
================================

Automake currently only includes full support for C, C++ (*note C++
Support::), Objective C (*note Objective C Support::), Objective C++
(*note Objective C++ Support::), Fortran 77 (*note Fortran 77
Support::), Fortran 9x (*note Fortran 9x Support::), and Java (*note
Java Support with gcj::).  There is only rudimentary support for other
languages, support for which will be improved based on user demand.

   Some limited support for adding your own languages is available via
the suffix rule handling (*note Suffixes::).

8.19 Automatic dependency tracking
==================================

As a developer it is often painful to continually update the
'Makefile.am' whenever the include-file dependencies change in a
project.  Automake supplies a way to automatically track dependency
changes (*note Dependency Tracking::).

   Automake always uses complete dependencies for a compilation,
including system headers.  Automake's model is that dependency
computation should be a side effect of the build.  To this end,
dependencies are computed by running all compilations through a special
wrapper program called 'depcomp'.  'depcomp' understands how to coax
many different C and C++ compilers into generating dependency
information in the format it requires.  'automake -a' will install
'depcomp' into your source tree for you.  If 'depcomp' can't figure out
how to properly invoke your compiler, dependency tracking will simply be
disabled for your build.

   Experience with earlier versions of Automake (*note Dependency
Tracking Evolution: (automake-history)Dependency Tracking Evolution.)
taught us that it is not reliable to generate dependencies only on the
maintainer's system, as configurations vary too much.  So instead
Automake implements dependency tracking at build time.

   Automatic dependency tracking can be suppressed by putting
'no-dependencies' in the variable 'AUTOMAKE_OPTIONS', or passing
'no-dependencies' as an argument to 'AM_INIT_AUTOMAKE' (this should be
the preferred way).  Or, you can invoke 'automake' with the '-i' option.
Dependency tracking is enabled by default.

   The person building your package also can choose to disable
dependency tracking by configuring with '--disable-dependency-tracking'.

8.20 Support for executable extensions
======================================

On some platforms, such as Windows, executables are expected to have an
extension such as '.exe'.  On these platforms, some compilers (GCC among
them) will automatically generate 'foo.exe' when asked to generate
'foo'.

   Automake provides mostly-transparent support for this.  Unfortunately
_mostly_ doesn't yet mean _fully_.  Until the English dictionary is
revised, you will have to assist Automake if your package must support
those platforms.

   One thing you must be aware of is that, internally, Automake rewrites
something like this:

     bin_PROGRAMS = liver

   to this:

     bin_PROGRAMS = liver$(EXEEXT)

   The targets Automake generates are likewise given the '$(EXEEXT)'
extension.

   The variables 'TESTS' and 'XFAIL_TESTS' (*note Simple Tests::) are
also rewritten if they contain filenames that have been declared as
programs in the same 'Makefile'.  (This is mostly useful when some
programs from 'check_PROGRAMS' are listed in 'TESTS'.)

   However, Automake cannot apply this rewriting to 'configure'
substitutions.  This means that if you are conditionally building a
program using such a substitution, then your 'configure.ac' must take
care to add '$(EXEEXT)' when constructing the output variable.

   Sometimes maintainers like to write an explicit link rule for their
program.  Without executable extension support, this is easy--you simply
write a rule whose target is the name of the program.  However, when
executable extension support is enabled, you must instead add the
'$(EXEEXT)' suffix.

   This might be a nuisance for maintainers who know their package will
never run on a platform that has executable extensions.  For those
maintainers, the 'no-exeext' option (*note Options::) will disable this
feature.  This works in a fairly ugly way; if 'no-exeext' is seen, then
the presence of a rule for a target named 'foo' in 'Makefile.am' will
override an 'automake'-generated rule for 'foo$(EXEEXT)'.  Without the
'no-exeext' option, this use will give a diagnostic.

9 Other Derived Objects
***********************

Automake can handle derived objects that are not C programs.  Sometimes
the support for actually building such objects must be explicitly
supplied, but Automake will still automatically handle installation and
distribution.

9.1 Executable Scripts
======================

It is possible to define and install programs that are scripts.  Such
programs are listed using the 'SCRIPTS' primary name.  When the script
is distributed in its final, installable form, the 'Makefile' usually
looks as follows:

     # Install my_script in $(bindir) and distribute it.
     dist_bin_SCRIPTS = my_script

   Scripts are not distributed by default; as we have just seen, those
that should be distributed can be specified using a 'dist_' prefix as
with other primaries.

   Scripts can be installed in 'bindir', 'sbindir', 'libexecdir',
'pkglibexecdir', or 'pkgdatadir'.

   Scripts that need not be installed can be listed in 'noinst_SCRIPTS',
and among them, those which are needed only by 'make check' should go in
'check_SCRIPTS'.

   When a script needs to be built, the 'Makefile.am' should include the
appropriate rules.  For instance the 'automake' program itself is a Perl
script that is generated from 'automake.in'.  Here is how this is
handled:

     bin_SCRIPTS = automake
     CLEANFILES = $(bin_SCRIPTS)
     EXTRA_DIST = automake.in

     do_subst = sed -e 's,[@]datadir[@],$(datadir),g' 
                 -e 's,[@]PERL[@],$(PERL),g' 
                 -e 's,[@]PACKAGE[@],$(PACKAGE),g' 
                 -e 's,[@]VERSION[@],$(VERSION),g' 
                 ...

     automake: automake.in Makefile
             $(do_subst) < $(srcdir)/automake.in > automake
             chmod +x automake

   Such scripts for which a build rule has been supplied need to be
deleted explicitly using 'CLEANFILES' (*note Clean::), and their sources
have to be distributed, usually with 'EXTRA_DIST' (*note Basics of
Distribution::).

   Another common way to build scripts is to process them from
'configure' with 'AC_CONFIG_FILES'.  In this situation Automake knows
which files should be cleaned and distributed, and what the rebuild
rules should look like.

   For instance if 'configure.ac' contains

     AC_CONFIG_FILES([src/my_script], [chmod +x src/my_script])

to build 'src/my_script' from 'src/my_script.in', then a
'src/Makefile.am' to install this script in '$(bindir)' can be as simple
as

     bin_SCRIPTS = my_script
     CLEANFILES = $(bin_SCRIPTS)

There is no need for 'EXTRA_DIST' or any build rule: Automake infers
them from 'AC_CONFIG_FILES' (*note Requirements::).  'CLEANFILES' is
still useful, because by default Automake will clean targets of
'AC_CONFIG_FILES' in 'distclean', not 'clean'.

   Although this looks simpler, building scripts this way has one
drawback: directory variables such as '$(datadir)' are not fully
expanded and may refer to other directory variables.

9.2 Header files
================

Header files that must be installed are specified by the 'HEADERS'
family of variables.  Headers can be installed in 'includedir',
'oldincludedir', 'pkgincludedir' or any other directory you may have
defined (*note Uniform::).  For instance,

     include_HEADERS = foo.h bar/bar.h

will install the two files as '$(includedir)/foo.h' and
'$(includedir)/bar.h'.

   The 'nobase_' prefix is also supported,

     nobase_include_HEADERS = foo.h bar/bar.h

will install the two files as '$(includedir)/foo.h' and
'$(includedir)/bar/bar.h' (*note Alternative::).

   Usually, only header files that accompany installed libraries need to
be installed.  Headers used by programs or convenience libraries are not
installed.  The 'noinst_HEADERS' variable can be used for such headers.
However when the header actually belongs to a single convenience library
or program, we recommend listing it in the program's or library's
'_SOURCES' variable (*note Program Sources::) instead of in
'noinst_HEADERS'.  This is clearer for the 'Makefile.am' reader.
'noinst_HEADERS' would be the right variable to use in a directory
containing only headers and no associated library or program.

   All header files must be listed somewhere; in a '_SOURCES' variable
or in a '_HEADERS' variable.  Missing ones will not appear in the
distribution.

   For header files that are built and must not be distributed, use the
'nodist_' prefix as in 'nodist_include_HEADERS' or
'nodist_prog_SOURCES'.  If these generated headers are needed during the
build, you must also ensure they exist before they are used (*note
Sources::).

9.3 Architecture-independent data files
=======================================

Automake supports the installation of miscellaneous data files using the
'DATA' family of variables.

   Such data can be installed in the directories 'datadir',
'sysconfdir', 'sharedstatedir', 'localstatedir', or 'pkgdatadir'.

   By default, data files are _not_ included in a distribution.  Of
course, you can use the 'dist_' prefix to change this on a per-variable
basis.

   Here is how Automake declares its auxiliary data files:

     dist_pkgdata_DATA = clean-kr.am clean.am ...

9.4 Built Sources
=================

Because Automake's automatic dependency tracking works as a side-effect
of compilation (*note Dependencies::) there is a bootstrap issue: a
target should not be compiled before its dependencies are made, but
these dependencies are unknown until the target is first compiled.

   Ordinarily this is not a problem, because dependencies are
distributed sources: they preexist and do not need to be built.  Suppose
that 'foo.c' includes 'foo.h'.  When it first compiles 'foo.o', 'make'
only knows that 'foo.o' depends on 'foo.c'.  As a side-effect of this
compilation 'depcomp' records the 'foo.h' dependency so that following
invocations of 'make' will honor it.  In these conditions, it's clear
there is no problem: either 'foo.o' doesn't exist and has to be built
(regardless of the dependencies), or accurate dependencies exist and
they can be used to decide whether 'foo.o' should be rebuilt.

   It's a different story if 'foo.h' doesn't exist by the first 'make'
run.  For instance, there might be a rule to build 'foo.h'.  This time
'file.o''s build will fail because the compiler can't find 'foo.h'.
'make' failed to trigger the rule to build 'foo.h' first by lack of
dependency information.

   The 'BUILT_SOURCES' variable is a workaround for this problem.  A
source file listed in 'BUILT_SOURCES' is made on 'make all' or 'make
check' (or even 'make install') before other targets are processed.
However, such a source file is not _compiled_ unless explicitly
requested by mentioning it in some other '_SOURCES' variable.

   So, to conclude our introductory example, we could use 'BUILT_SOURCES
= foo.h' to ensure 'foo.h' gets built before any other target (including
'foo.o') during 'make all' or 'make check'.

   'BUILT_SOURCES' is actually a bit of a misnomer, as any file which
must be created early in the build process can be listed in this
variable.  Moreover, all built sources do not necessarily have to be
listed in 'BUILT_SOURCES'.  For instance, a generated '.c' file doesn't
need to appear in 'BUILT_SOURCES' (unless it is included by another
source), because it's a known dependency of the associated object.

   It might be important to emphasize that 'BUILT_SOURCES' is honored
only by 'make all', 'make check' and 'make install'.  This means you
cannot build a specific target (e.g., 'make foo') in a clean tree if it
depends on a built source.  However it will succeed if you have run
'make all' earlier, because accurate dependencies are already available.

   The next section illustrates and discusses the handling of built
sources on a toy example.

9.4.1 Built Sources Example
---------------------------

Suppose that 'foo.c' includes 'bindir.h', which is
installation-dependent and not distributed: it needs to be built.  Here
'bindir.h' defines the preprocessor macro 'bindir' to the value of the
'make' variable 'bindir' (inherited from 'configure').

   We suggest several implementations below.  It's not meant to be an
exhaustive listing of all ways to handle built sources, but it will give
you a few ideas if you encounter this issue.

First Try
.........

This first implementation will illustrate the bootstrap issue mentioned
in the previous section (*note Sources::).

   Here is a tentative 'Makefile.am'.

     # This won't work.
     bin_PROGRAMS = foo
     foo_SOURCES = foo.c
     nodist_foo_SOURCES = bindir.h
     CLEANFILES = bindir.h
     bindir.h: Makefile
             echo '#define bindir "$(bindir)"' >$@

   This setup doesn't work, because Automake doesn't know that 'foo.c'
includes 'bindir.h'.  Remember, automatic dependency tracking works as a
side-effect of compilation, so the dependencies of 'foo.o' will be known
only after 'foo.o' has been compiled (*note Dependencies::).  The
symptom is as follows.

     % make
     source='foo.c' object='foo.o' libtool=no 
     depfile='.deps/foo.Po' tmpdepfile='.deps/foo.TPo' 
     depmode=gcc /bin/sh ./depcomp 
     gcc -I. -I. -g -O2 -c `test -f 'foo.c' || echo './'`foo.c
     foo.c:2: bindir.h: No such file or directory
     make: *** [foo.o] Error 1

   In this example 'bindir.h' is not distributed nor installed, and it
is not even being built on-time.  One may wonder if the
'nodist_foo_SOURCES = bindir.h' line has any use at all.  This line
simply states that 'bindir.h' is a source of 'foo', so for instance, it
should be inspected while generating tags (*note Tags::).  In other
words, it does not help our present problem, and the build would fail
identically without it.

Using 'BUILT_SOURCES'
.....................

A solution is to require 'bindir.h' to be built before anything else.
This is what 'BUILT_SOURCES' is meant for (*note Sources::).

     bin_PROGRAMS = foo
     foo_SOURCES = foo.c
     nodist_foo_SOURCES = bindir.h
     BUILT_SOURCES = bindir.h
     CLEANFILES = bindir.h
     bindir.h: Makefile
             echo '#define bindir "$(bindir)"' >$@

   See how 'bindir.h' gets built first:

     % make
     echo '#define bindir "/usr/local/bin"' >bindir.h
     make  all-am
     make[1]: Entering directory `/home/adl/tmp'
     source='foo.c' object='foo.o' libtool=no 
     depfile='.deps/foo.Po' tmpdepfile='.deps/foo.TPo' 
     depmode=gcc /bin/sh ./depcomp 
     gcc -I. -I. -g -O2 -c `test -f 'foo.c' || echo './'`foo.c
     gcc  -g -O2   -o foo  foo.o
     make[1]: Leaving directory `/home/adl/tmp'

   However, as said earlier, 'BUILT_SOURCES' applies only to the 'all',
'check', and 'install' targets.  It still fails if you try to run 'make
foo' explicitly:

     % make clean
     test -z "bindir.h" || rm -f bindir.h
     test -z "foo" || rm -f foo
     rm -f *.o
     % : > .deps/foo.Po # Suppress previously recorded dependencies
     % make foo
     source='foo.c' object='foo.o' libtool=no 
     depfile='.deps/foo.Po' tmpdepfile='.deps/foo.TPo' 
     depmode=gcc /bin/sh ./depcomp 
     gcc -I. -I. -g -O2 -c `test -f 'foo.c' || echo './'`foo.c
     foo.c:2: bindir.h: No such file or directory
     make: *** [foo.o] Error 1

Recording Dependencies manually
...............................

Usually people are happy enough with 'BUILT_SOURCES' because they never
build targets such as 'make foo' before 'make all', as in the previous
example.  However if this matters to you, you can avoid 'BUILT_SOURCES'
and record such dependencies explicitly in the 'Makefile.am'.

     bin_PROGRAMS = foo
     foo_SOURCES = foo.c
     nodist_foo_SOURCES = bindir.h
     foo.$(OBJEXT): bindir.h
     CLEANFILES = bindir.h
     bindir.h: Makefile
             echo '#define bindir "$(bindir)"' >$@

   You don't have to list _all_ the dependencies of 'foo.o' explicitly,
only those that might need to be built.  If a dependency already exists,
it will not hinder the first compilation and will be recorded by the
normal dependency tracking code.  (Note that after this first
compilation the dependency tracking code will also have recorded the
dependency between 'foo.o' and 'bindir.h'; so our explicit dependency is
really useful to the first build only.)

   Adding explicit dependencies like this can be a bit dangerous if you
are not careful enough.  This is due to the way Automake tries not to
overwrite your rules (it assumes you know better than it).
'foo.$(OBJEXT): bindir.h' supersedes any rule Automake may want to
output to build 'foo.$(OBJEXT)'.  It happens to work in this case
because Automake doesn't have to output any 'foo.$(OBJEXT):' target: it
relies on a suffix rule instead (i.e., '.c.$(OBJEXT):').  Always check
the generated 'Makefile.in' if you do this.

Build 'bindir.h' from 'configure'
.................................

It's possible to define this preprocessor macro from 'configure', either
in 'config.h' (*note Defining Directories: (autoconf)Defining
Directories.), or by processing a 'bindir.h.in' file using
'AC_CONFIG_FILES' (*note Configuration Actions: (autoconf)Configuration
Actions.).

   At this point it should be clear that building 'bindir.h' from
'configure' works well for this example.  'bindir.h' will exist before
you build any target, hence will not cause any dependency issue.

   The Makefile can be shrunk as follows.  We do not even have to
mention 'bindir.h'.

     bin_PROGRAMS = foo
     foo_SOURCES = foo.c

   However, it's not always possible to build sources from 'configure',
especially when these sources are generated by a tool that needs to be
built first.

Build 'bindir.c', not 'bindir.h'.
.................................

Another attractive idea is to define 'bindir' as a variable or function
exported from 'bindir.o', and build 'bindir.c' instead of 'bindir.h'.

     noinst_PROGRAMS = foo
     foo_SOURCES = foo.c bindir.h
     nodist_foo_SOURCES = bindir.c
     CLEANFILES = bindir.c
     bindir.c: Makefile
             echo 'const char bindir[] = "$(bindir)";' >$@

   'bindir.h' contains just the variable's declaration and doesn't need
to be built, so it won't cause any trouble.  'bindir.o' is always
dependent on 'bindir.c', so 'bindir.c' will get built first.

Which is best?
..............

There is no panacea, of course.  Each solution has its merits and
drawbacks.

   You cannot use 'BUILT_SOURCES' if the ability to run 'make foo' on a
clean tree is important to you.

   You won't add explicit dependencies if you are leery of overriding an
Automake rule by mistake.

   Building files from './configure' is not always possible, neither is
converting '.h' files into '.c' files.

10 Other GNU Tools
******************

Since Automake is primarily intended to generate 'Makefile.in's for use
in GNU programs, it tries hard to interoperate with other GNU tools.

10.1 Emacs Lisp
===============

Automake provides some support for Emacs Lisp.  The 'LISP' primary is
used to hold a list of '.el' files.  Possible prefixes for this primary
are 'lisp_' and 'noinst_'.  Note that if 'lisp_LISP' is defined, then
'configure.ac' must run 'AM_PATH_LISPDIR' (*note Macros::).

   Lisp sources are not distributed by default.  You can prefix the
'LISP' primary with 'dist_', as in 'dist_lisp_LISP' or
'dist_noinst_LISP', to indicate that these files should be distributed.

   Automake will byte-compile all Emacs Lisp source files using the
Emacs found by 'AM_PATH_LISPDIR', if any was found.  When performing
such byte-compilation, the flags specified in the (developer-reserved)
'AM_ELCFLAGS' and (user-reserved) 'ELCFLAGS' make variables will be
passed to the Emacs invocation.

   Byte-compiled Emacs Lisp files are not portable among all versions of
Emacs, so it makes sense to turn this off if you expect sites to have
more than one version of Emacs installed.  Furthermore, many packages
don't actually benefit from byte-compilation.  Still, we recommend that
you byte-compile your Emacs Lisp sources.  It is probably better for
sites with strange setups to cope for themselves than to make the
installation less nice for everybody else.

   There are two ways to avoid byte-compiling.  Historically, we have
recommended the following construct.

     lisp_LISP = file1.el file2.el
     ELCFILES =

'ELCFILES' is an internal Automake variable that normally lists all
'.elc' files that must be byte-compiled.  Automake defines 'ELCFILES'
automatically from 'lisp_LISP'.  Emptying this variable explicitly
prevents byte-compilation.

   Since Automake 1.8, we now recommend using 'lisp_DATA' instead:

     lisp_DATA = file1.el file2.el

   Note that these two constructs are not equivalent.  '_LISP' will not
install a file if Emacs is not installed, while '_DATA' will always
install its files.

10.2 Gettext
============

If 'AM_GNU_GETTEXT' is seen in 'configure.ac', then Automake turns on
support for GNU gettext, a message catalog system for
internationalization (*note Introduction: (gettext)Top.).

   The 'gettext' support in Automake requires the addition of one or two
subdirectories to the package: 'po' and possibly also 'intl'.  The
latter is needed if 'AM_GNU_GETTEXT' is not invoked with the 'external'
argument, or if 'AM_GNU_GETTEXT_INTL_SUBDIR' is used.  Automake ensures
that these directories exist and are mentioned in 'SUBDIRS'.

10.3 Libtool
============

Automake provides support for GNU Libtool (*note Introduction:
(libtool)Top.) with the 'LTLIBRARIES' primary.  *Note A Shared
Library::.

10.4 Java bytecode compilation (deprecated)
===========================================

Automake provides some minimal support for Java bytecode compilation
with the 'JAVA' primary (in addition to the support for compiling Java
to native machine code; *note Java Support with gcj::).  Note however
that _the interface and most features described here are deprecated_.
Future Automake releases will strive to provide a better and cleaner
interface, which however _won't be backward-compatible_; the present
interface will probably be removed altogether some time after the
introduction of the new interface (if that ever materializes).

   Any '.java' files listed in a '_JAVA' variable will be compiled with
'JAVAC' at build time.  By default, '.java' files are not included in
the distribution, you should use the 'dist_' prefix to distribute them.

   Here is a typical setup for distributing '.java' files and installing
the '.class' files resulting from their compilation.

     javadir = $(datadir)/java
     dist_java_JAVA = a.java b.java ...

   Currently Automake enforces the restriction that only one '_JAVA'
primary can be used in a given 'Makefile.am'.  The reason for this
restriction is that, in general, it isn't possible to know which
'.class' files were generated from which '.java' files, so it would be
impossible to know which files to install where.  For instance, a
'.java' file can define multiple classes; the resulting '.class' file
names cannot be predicted without parsing the '.java' file.

   There are a few variables that are used when compiling Java sources:

'JAVAC'
     The name of the Java compiler.  This defaults to 'javac'.

'JAVACFLAGS'
     The flags to pass to the compiler.  This is considered to be a user
     variable (*note User Variables::).

'AM_JAVACFLAGS'
     More flags to pass to the Java compiler.  This, and not
     'JAVACFLAGS', should be used when it is necessary to put Java
     compiler flags into 'Makefile.am'.

'JAVAROOT'
     The value of this variable is passed to the '-d' option to 'javac'.
     It defaults to '$(top_builddir)'.

'CLASSPATH_ENV'
     This variable is a shell expression that is used to set the
     'CLASSPATH' environment variable on the 'javac' command line.  (In
     the future we will probably handle class path setting differently.)

10.5 Python
===========

Automake provides support for Python compilation with the 'PYTHON'
primary.  A typical setup is to call 'AM_PATH_PYTHON' in 'configure.ac'
and use a line like the following in 'Makefile.am':

     python_PYTHON = tree.py leave.py

   Any files listed in a '_PYTHON' variable will be byte-compiled with
'py-compile' at install time.  'py-compile' actually creates both
standard ('.pyc') and optimized ('.pyo') byte-compiled versions of the
source files.  Note that because byte-compilation occurs at install
time, any files listed in 'noinst_PYTHON' will not be compiled.  Python
source files are included in the distribution by default, prepend
'nodist_' (as in 'nodist_python_PYTHON') to omit them.

   Automake ships with an Autoconf macro called 'AM_PATH_PYTHON' that
will determine some Python-related directory variables (see below).  If
you have called 'AM_PATH_PYTHON' from 'configure.ac', then you may use
the variables 'python_PYTHON' or 'pkgpython_PYTHON' to list Python
source files in your 'Makefile.am', depending on where you want your
files installed (see the definitions of 'pythondir' and 'pkgpythondir'
below).

 -- Macro: AM_PATH_PYTHON ([VERSION], [ACTION-IF-FOUND],
     [ACTION-IF-NOT-FOUND])

     Search for a Python interpreter on the system.  This macro takes
     three optional arguments.  The first argument, if present, is the
     minimum version of Python required for this package:
     'AM_PATH_PYTHON' will skip any Python interpreter that is older
     than VERSION.  If an interpreter is found and satisfies VERSION,
     then ACTION-IF-FOUND is run.  Otherwise, ACTION-IF-NOT-FOUND is
     run.

     If ACTION-IF-NOT-FOUND is not specified, as in the following
     example, the default is to abort 'configure'.

          AM_PATH_PYTHON([2.2])

     This is fine when Python is an absolute requirement for the
     package.  If Python >= 2.5 was only _optional_ to the package,
     'AM_PATH_PYTHON' could be called as follows.

          AM_PATH_PYTHON([2.5],, [:])

     If the 'PYTHON' variable is set when 'AM_PATH_PYTHON' is called,
     then that will be the only Python interpreter that is tried.

     'AM_PATH_PYTHON' creates the following output variables based on
     the Python installation found during configuration.

'PYTHON'
     The name of the Python executable, or ':' if no suitable
     interpreter could be found.

     Assuming ACTION-IF-NOT-FOUND is used (otherwise './configure' will
     abort if Python is absent), the value of 'PYTHON' can be used to
     setup a conditional in order to disable the relevant part of a
     build as follows.

          AM_PATH_PYTHON(,, [:])
          AM_CONDITIONAL([HAVE_PYTHON], [test "$PYTHON" != :])

'PYTHON_VERSION'
     The Python version number, in the form MAJOR.MINOR (e.g., '2.5').
     This is currently the value of 'sys.version[:3]'.

'PYTHON_PREFIX'
     The string '${prefix}'.  This term may be used in future work that
     needs the contents of Python's 'sys.prefix', but general consensus
     is to always use the value from 'configure'.

'PYTHON_EXEC_PREFIX'
     The string '${exec_prefix}'.  This term may be used in future work
     that needs the contents of Python's 'sys.exec_prefix', but general
     consensus is to always use the value from 'configure'.

'PYTHON_PLATFORM'
     The canonical name used by Python to describe the operating system,
     as given by 'sys.platform'.  This value is sometimes needed when
     building Python extensions.

'pythondir'
     The directory name for the 'site-packages' subdirectory of the
     standard Python install tree.

'pkgpythondir'
     This is the directory under 'pythondir' that is named after the
     package.  That is, it is '$(pythondir)/$(PACKAGE)'.  It is provided
     as a convenience.

'pyexecdir'
     This is the directory where Python extension modules (shared
     libraries) should be installed.  An extension module written in C
     could be declared as follows to Automake:

          pyexec_LTLIBRARIES = quaternion.la
          quaternion_la_SOURCES = quaternion.c support.c support.h
          quaternion_la_LDFLAGS = -avoid-version -module

'pkgpyexecdir'
     This is a convenience variable that is defined as
     '$(pyexecdir)/$(PACKAGE)'.

   All of these directory variables have values that start with either
'${prefix}' or '${exec_prefix}' unexpanded.  This works fine in
'Makefiles', but it makes these variables hard to use in 'configure'.
This is mandated by the GNU coding standards, so that the user can run
'make prefix=/foo install'.  The Autoconf manual has a section with more
details on this topic (*note Installation Directory Variables:
(autoconf)Installation Directory Variables.).  See also *note Hard-Coded
Install Paths::.

11 Building documentation
*************************

Currently Automake provides support for Texinfo and man pages.

11.1 Texinfo
============

If the current directory contains Texinfo source, you must declare it
with the 'TEXINFOS' primary.  Generally Texinfo files are converted into
info, and thus the 'info_TEXINFOS' variable is most commonly used here.
Any Texinfo source file should have the '.texi' extension.  Automake
also accepts '.txi' or '.texinfo' extensions, but their use is
discouraged now, and will elicit runtime warnings.

   Automake generates rules to build '.info', '.dvi', '.ps', '.pdf' and
'.html' files from your Texinfo sources.  Following the GNU Coding
Standards, only the '.info' files are built by 'make all' and installed
by 'make install' (unless you use 'no-installinfo', see below).
Furthermore, '.info' files are automatically distributed so that Texinfo
is not a prerequisite for installing your package.

   It is worth noting that, contrary to what happens with the other
formats, the generated '.info' files are by default placed in 'srcdir'
rather than in the 'builddir'.  This can be changed with the
'info-in-builddir' option.

   Other documentation formats can be built on request by 'make dvi',
'make ps', 'make pdf' and 'make html', and they can be installed with
'make install-dvi', 'make install-ps', 'make install-pdf' and 'make
install-html' explicitly.  'make uninstall' will remove everything: the
Texinfo documentation installed by default as well as all the above
optional formats.

   All of these targets can be extended using '-local' rules (*note
Extending::).

   If the '.texi' file '@include's 'version.texi', then that file will
be automatically generated.  The file 'version.texi' defines four
Texinfo flag you can reference using '@value{EDITION}',
'@value{VERSION}', '@value{UPDATED}', and '@value{UPDATED-MONTH}'.

'EDITION'
'VERSION'
     Both of these flags hold the version number of your program.  They
     are kept separate for clarity.

'UPDATED'
     This holds the date the primary '.texi' file was last modified.

'UPDATED-MONTH'
     This holds the name of the month in which the primary '.texi' file
     was last modified.

   The 'version.texi' support requires the 'mdate-sh' script; this
script is supplied with Automake and automatically included when
'automake' is invoked with the '--add-missing' option.

   If you have multiple Texinfo files, and you want to use the
'version.texi' feature, then you have to have a separate version file
for each Texinfo file.  Automake will treat any include in a Texinfo
file that matches 'vers*.texi' just as an automatically generated
version file.

   Sometimes an info file actually depends on more than one '.texi'
file.  For instance, in GNU Hello, 'hello.texi' includes the file
'fdl.texi'.  You can tell Automake about these dependencies using the
'TEXI_TEXINFOS' variable.  Here is how GNU Hello does it:

     info_TEXINFOS = hello.texi
     hello_TEXINFOS = fdl.texi

   By default, Automake requires the file 'texinfo.tex' to appear in the
same directory as the 'Makefile.am' file that lists the '.texi' files.
If you used 'AC_CONFIG_AUX_DIR' in 'configure.ac' (*note Finding
'configure' Input: (autoconf)Input.), then 'texinfo.tex' is looked for
there.  In both cases, 'automake' then supplies 'texinfo.tex' if
'--add-missing' is given, and takes care of its distribution.  However,
if you set the 'TEXINFO_TEX' variable (see below), it overrides the
location of the file and turns off its installation into the source as
well as its distribution.

   The option 'no-texinfo.tex' can be used to eliminate the requirement
for the file 'texinfo.tex'.  Use of the variable 'TEXINFO_TEX' is
preferable, however, because that allows the 'dvi', 'ps', and 'pdf'
targets to still work.

   Automake generates an 'install-info' rule; some people apparently use
this.  By default, info pages are installed by 'make install', so
running 'make install-info' is pointless.  This can be prevented via the
'no-installinfo' option.  In this case, '.info' files are not installed
by default, and user must request this explicitly using 'make
install-info'.

   By default, 'make install-info' and 'make uninstall-info' will try to
run the 'install-info' program (if available) to update (or
create/remove) the '${infodir}/dir' index.  If this is undesired, it can
be prevented by exporting the 'AM_UPDATE_INFO_DIR' variable to "'no'".

   The following variables are used by the Texinfo build rules.

'MAKEINFO'
     The name of the program invoked to build '.info' files.  This
     variable is defined by Automake.  If the 'makeinfo' program is
     found on the system then it will be used by default; otherwise
     'missing' will be used instead.

'MAKEINFOHTML'
     The command invoked to build '.html' files.  Automake defines this
     to '$(MAKEINFO) --html'.

'MAKEINFOFLAGS'
     User flags passed to each invocation of '$(MAKEINFO)' and
     '$(MAKEINFOHTML)'.  This user variable (*note User Variables::) is
     not expected to be defined in any 'Makefile'; it can be used by
     users to pass extra flags to suit their needs.

'AM_MAKEINFOFLAGS'
'AM_MAKEINFOHTMLFLAGS'
     Maintainer flags passed to each 'makeinfo' invocation.  Unlike
     'MAKEINFOFLAGS', these variables are meant to be defined by
     maintainers in 'Makefile.am'.  '$(AM_MAKEINFOFLAGS)' is passed to
     'makeinfo' when building '.info' files; and
     '$(AM_MAKEINFOHTMLFLAGS)' is used when building '.html' files.

     For instance, the following setting can be used to obtain one
     single '.html' file per manual, without node separators.
          AM_MAKEINFOHTMLFLAGS = --no-headers --no-split

     'AM_MAKEINFOHTMLFLAGS' defaults to '$(AM_MAKEINFOFLAGS)'.  This
     means that defining 'AM_MAKEINFOFLAGS' without defining
     'AM_MAKEINFOHTMLFLAGS' will impact builds of both '.info' and
     '.html' files.

'TEXI2DVI'
     The name of the command that converts a '.texi' file into a '.dvi'
     file.  This defaults to 'texi2dvi', a script that ships with the
     Texinfo package.

'TEXI2PDF'
     The name of the command that translates a '.texi' file into a
     '.pdf' file.  This defaults to '$(TEXI2DVI) --pdf --batch'.

'DVIPS'
     The name of the command that builds a '.ps' file out of a '.dvi'
     file.  This defaults to 'dvips'.

'TEXINFO_TEX'

     If your package has Texinfo files in many directories, you can use
     the variable 'TEXINFO_TEX' to tell Automake where to find the
     canonical 'texinfo.tex' for your package.  The value of this
     variable should be the relative path from the current 'Makefile.am'
     to 'texinfo.tex':

          TEXINFO_TEX = ../doc/texinfo.tex

11.2 Man Pages
==============

A package can also include man pages (but see the GNU standards on this
matter, *note (standards)Man Pages::.)  Man pages are declared using the
'MANS' primary.  Generally the 'man_MANS' variable is used.  Man pages
are automatically installed in the correct subdirectory of 'mandir',
based on the file extension.

   File extensions such as '.1c' are handled by looking for the valid
part of the extension and using that to determine the correct
subdirectory of 'mandir'.  Valid section names are the digits '0'
through '9', and the letters 'l' and 'n'.

   Sometimes developers prefer to name a man page something like
'foo.man' in the source, and then rename it to have the correct suffix,
for example 'foo.1', when installing the file.  Automake also supports
this mode.  For a valid section named SECTION, there is a corresponding
directory named 'manSECTIONdir', and a corresponding '_MANS' variable.
Files listed in such a variable are installed in the indicated section.
If the file already has a valid suffix, then it is installed as-is;
otherwise the file suffix is changed to match the section.

   For instance, consider this example:
     man1_MANS = rename.man thesame.1 alsothesame.1c

In this case, 'rename.man' will be renamed to 'rename.1' when installed,
but the other files will keep their names.

   By default, man pages are installed by 'make install'.  However,
since the GNU project does not require man pages, many maintainers do
not expend effort to keep the man pages up to date.  In these cases, the
'no-installman' option will prevent the man pages from being installed
by default.  The user can still explicitly install them via 'make
install-man'.

   For fast installation, with many files it is preferable to use
'manSECTION_MANS' over 'man_MANS' as well as files that do not need to
be renamed.

   Man pages are not currently considered to be source, because it is
not uncommon for man pages to be automatically generated.  Therefore
they are not automatically included in the distribution.  However, this
can be changed by use of the 'dist_' prefix.  For instance here is how
to distribute and install the two man pages of GNU 'cpio' (which
includes both Texinfo documentation and man pages):

     dist_man_MANS = cpio.1 mt.1

   The 'nobase_' prefix is meaningless for man pages and is disallowed.

   Executables and manpages may be renamed upon installation (*note
Renaming::).  For manpages this can be avoided by use of the 'notrans_'
prefix.  For instance, suppose an executable 'foo' allowing to access a
library function 'foo' from the command line.  The way to avoid renaming
of the 'foo.3' manpage is:

     man_MANS = foo.1
     notrans_man_MANS = foo.3

   'notrans_' must be specified first when used in conjunction with
either 'dist_' or 'nodist_' (*note Fine-grained Distribution Control::).
For instance:

     notrans_dist_man3_MANS = bar.3

12 What Gets Installed
**********************

Naturally, Automake handles the details of actually installing your
program once it has been built.  All files named by the various
primaries are automatically installed in the appropriate places when the
user runs 'make install'.

12.1 Basics of Installation
===========================

A file named in a primary is installed by copying the built file into
the appropriate directory.  The base name of the file is used when
installing.

     bin_PROGRAMS = hello subdir/goodbye

   In this example, both 'hello' and 'goodbye' will be installed in
'$(bindir)'.

   Sometimes it is useful to avoid the basename step at install time.
For instance, you might have a number of header files in subdirectories
of the source tree that are laid out precisely how you want to install
them.  In this situation you can use the 'nobase_' prefix to suppress
the base name step.  For example:

     nobase_include_HEADERS = stdio.h sys/types.h

will install 'stdio.h' in '$(includedir)' and 'types.h' in
'$(includedir)/sys'.

   For most file types, Automake will install multiple files at once,
while avoiding command line length issues (*note Length Limitations::).
Since some 'install' programs will not install the same file twice in
one invocation, you may need to ensure that file lists are unique within
one variable such as 'nobase_include_HEADERS' above.

   You should not rely on the order in which files listed in one
variable are installed.  Likewise, to cater for parallel make, you
should not rely on any particular file installation order even among
different file types (library dependencies are an exception here).

12.2 The Two Parts of Install
=============================

Automake generates separate 'install-data' and 'install-exec' rules, in
case the installer is installing on multiple machines that share
directory structure--these targets allow the machine-independent parts
to be installed only once.  'install-exec' installs platform-dependent
files, and 'install-data' installs platform-independent files.  The
'install' target depends on both of these targets.  While Automake tries
to automatically segregate objects into the correct category, the
'Makefile.am' author is, in the end, responsible for making sure this is
done correctly.

   Variables using the standard directory prefixes 'data', 'info',
'man', 'include', 'oldinclude', 'pkgdata', or 'pkginclude' are installed
by 'install-data'.

   Variables using the standard directory prefixes 'bin', 'sbin',
'libexec', 'sysconf', 'localstate', 'lib', or 'pkglib' are installed by
'install-exec'.

   For instance, 'data_DATA' files are installed by 'install-data',
while 'bin_PROGRAMS' files are installed by 'install-exec'.

   Any variable using a user-defined directory prefix with 'exec' in the
name (e.g., 'myexecbin_PROGRAMS') is installed by 'install-exec'.  All
other user-defined prefixes are installed by 'install-data'.

12.3 Extending Installation
===========================

It is possible to extend this mechanism by defining an
'install-exec-local' or 'install-data-local' rule.  If these rules
exist, they will be run at 'make install' time.  These rules can do
almost anything; care is required.

   Automake also supports two install hooks, 'install-exec-hook' and
'install-data-hook'.  These hooks are run after all other install rules
of the appropriate type, exec or data, have completed.  So, for
instance, it is possible to perform post-installation modifications
using an install hook.  *Note Extending::, for some examples.

12.4 Staged Installs
====================

Automake generates support for the 'DESTDIR' variable in all install
rules.  'DESTDIR' is used during the 'make install' step to relocate
install objects into a staging area.  Each object and path is prefixed
with the value of 'DESTDIR' before being copied into the install area.
Here is an example of typical DESTDIR usage:

     mkdir /tmp/staging &&
     make DESTDIR=/tmp/staging install

   The 'mkdir' command avoids a security problem if the attacker creates
a symbolic link from '/tmp/staging' to a victim area; then 'make' places
install objects in a directory tree built under '/tmp/staging'.  If
'/gnu/bin/foo' and '/gnu/share/aclocal/foo.m4' are to be installed, the
above command would install '/tmp/staging/gnu/bin/foo' and
'/tmp/staging/gnu/share/aclocal/foo.m4'.

   This feature is commonly used to build install images and packages
(*note DESTDIR::).

   Support for 'DESTDIR' is implemented by coding it directly into the
install rules.  If your 'Makefile.am' uses a local install rule (e.g.,
'install-exec-local') or an install hook, then you must write that code
to respect 'DESTDIR'.

   *Note (standards)Makefile Conventions::, for another usage example.

12.5 Install Rules for the User
===============================

Automake also generates rules for targets 'uninstall', 'installdirs',
and 'install-strip'.

   Automake supports 'uninstall-local' and 'uninstall-hook'.  There is
no notion of separate uninstalls for "exec" and "data", as these
features would not provide additional functionality.

   Note that 'uninstall' is not meant as a replacement for a real
packaging tool.

13 What Gets Cleaned
********************

The GNU Makefile Standards specify a number of different clean rules.
*Note Standard Targets for Users: (standards)Standard Targets.

   Generally the files that can be cleaned are determined automatically
by Automake.  Of course, Automake also recognizes some variables that
can be defined to specify additional files to clean.  These variables
are 'MOSTLYCLEANFILES', 'CLEANFILES', 'DISTCLEANFILES', and
'MAINTAINERCLEANFILES'.

   When cleaning involves more than deleting some hard-coded list of
files, it is also possible to supplement the cleaning rules with your
own commands.  Simply define a rule for any of the 'mostlyclean-local',
'clean-local', 'distclean-local', or 'maintainer-clean-local' targets
(*note Extending::).  A common case is deleting a directory, for
instance, a directory created by the test suite:

     clean-local:
             -rm -rf testSubDir

   Since 'make' allows only one set of rules for a given target, a more
extensible way of writing this is to use a separate target listed as a
dependency:

     clean-local: clean-local-check
     .PHONY: clean-local-check
     clean-local-check:
             -rm -rf testSubDir

   As the GNU Standards aren't always explicit as to which files should
be removed by which rule, we've adopted a heuristic that we believe was
first formulated by Franc,ois Pinard:

   * If 'make' built it, and it is commonly something that one would
     want to rebuild (for instance, a '.o' file), then 'mostlyclean'
     should delete it.

   * Otherwise, if 'make' built it, then 'clean' should delete it.

   * If 'configure' built it, then 'distclean' should delete it.

   * If the maintainer built it (for instance, a '.info' file), then
     'maintainer-clean' should delete it.  However 'maintainer-clean'
     should not delete anything that needs to exist in order to run
     './configure && make'.

   We recommend that you follow this same set of heuristics in your
'Makefile.am'.

14 What Goes in a Distribution
******************************

14.1 Basics of Distribution
===========================

The 'dist' rule in the generated 'Makefile.in' can be used to generate a
gzipped 'tar' file and other flavors of archive for distribution.  The
file is named based on the 'PACKAGE' and 'VERSION' variables defined by
'AM_INIT_AUTOMAKE' (*note Macros::); more precisely the gzipped 'tar'
file is named 'PACKAGE-VERSION.tar.gz'.  You can use the 'make' variable
'GZIP_ENV' to control how gzip is run.  The default setting is '--best'.

   For the most part, the files to distribute are automatically found by
Automake: all source files are automatically included in a distribution,
as are all 'Makefile.am' and 'Makefile.in' files.  Automake also has a
built-in list of commonly used files that are automatically included if
they are found in the current directory (either physically, or as the
target of a 'Makefile.am' rule); this list is printed by 'automake
--help'.  Note that some files in this list are actually distributed
only if other certain conditions hold (for example, the 'config.h.top'
and 'config.h.bot' files are automatically distributed only if, e.g.,
'AC_CONFIG_HEADERS([config.h])' is used in 'configure.ac').  Also, files
that are read by 'configure' (i.e. the source files corresponding to the
files specified in various Autoconf macros such as 'AC_CONFIG_FILES' and
siblings) are automatically distributed.  Files included in a
'Makefile.am' (using 'include') or in 'configure.ac' (using
'm4_include'), and helper scripts installed with 'automake
--add-missing' are also distributed.

   Still, sometimes there are files that must be distributed, but which
are not covered in the automatic rules.  These files should be listed in
the 'EXTRA_DIST' variable.  You can mention files from subdirectories in
'EXTRA_DIST'.

   You can also mention a directory in 'EXTRA_DIST'; in this case the
entire directory will be recursively copied into the distribution.
Please note that this will also copy _everything_ in the directory,
including, e.g., Subversion's '.svn' private directories or CVS/RCS
version control files; thus we recommend against using this feature
as-is.  However, you can use the 'dist-hook' feature to ameliorate the
problem; *note The dist Hook::.

   If you define 'SUBDIRS', Automake will recursively include the
subdirectories in the distribution.  If 'SUBDIRS' is defined
conditionally (*note Conditionals::), Automake will normally include all
directories that could possibly appear in 'SUBDIRS' in the distribution.
If you need to specify the set of directories conditionally, you can set
the variable 'DIST_SUBDIRS' to the exact list of subdirectories to
include in the distribution (*note Conditional Subdirectories::).

14.2 Fine-grained Distribution Control
======================================

Sometimes you need tighter control over what does _not_ go into the
distribution; for instance, you might have source files that are
generated and that you do not want to distribute.  In this case Automake
gives fine-grained control using the 'dist' and 'nodist' prefixes.  Any
primary or '_SOURCES' variable can be prefixed with 'dist_' to add the
listed files to the distribution.  Similarly, 'nodist_' can be used to
omit the files from the distribution.

   As an example, here is how you would cause some data to be
distributed while leaving some source code out of the distribution:

     dist_data_DATA = distribute-this
     bin_PROGRAMS = foo
     nodist_foo_SOURCES = do-not-distribute.c

14.3 The dist Hook
==================

Occasionally it is useful to be able to change the distribution before
it is packaged up.  If the 'dist-hook' rule exists, it is run after the
distribution directory is filled, but before the actual distribution
archives are created.  One way to use this is for removing unnecessary
files that get recursively included by specifying a directory in
'EXTRA_DIST':

     EXTRA_DIST = doc
     dist-hook:
             rm -rf `find $(distdir)/doc -type d -name .svn`

Note that the 'dist-hook' recipe shouldn't assume that the regular files
in the distribution directory are writable; this might not be the case
if one is packaging from a read-only source tree, or when a 'make
distcheck' is being done.  For similar reasons, the recipe shouldn't
assume that the subdirectories put into the distribution directory as
effect of having them listed in 'EXTRA_DIST' are writable.  So, if the
'dist-hook' recipe wants to modify the content of an existing file (or
'EXTRA_DIST' subdirectory) in the distribution directory, it should
explicitly to make it writable first:

     EXTRA_DIST = README doc
     dist-hook:
             chmod u+w $(distdir)/README $(distdir)/doc
             echo "Distribution date: `date`" >> README
             rm -f $(distdir)/doc/HACKING

   Two variables that come handy when writing 'dist-hook' rules are
'$(distdir)' and '$(top_distdir)'.

   '$(distdir)' points to the directory where the 'dist' rule will copy
files from the current directory before creating the tarball.  If you
are at the top-level directory, then 'distdir = $(PACKAGE)-$(VERSION)'.
When used from subdirectory named 'foo/', then 'distdir =
../$(PACKAGE)-$(VERSION)/foo'.  '$(distdir)' can be a relative or
absolute path, do not assume any form.

   '$(top_distdir)' always points to the root directory of the
distributed tree.  At the top-level it's equal to '$(distdir)'.  In the
'foo/' subdirectory 'top_distdir = ../$(PACKAGE)-$(VERSION)'.
'$(top_distdir)' too can be a relative or absolute path.

   Note that when packages are nested using 'AC_CONFIG_SUBDIRS' (*note
Subpackages::), then '$(distdir)' and '$(top_distdir)' are relative to
the package where 'make dist' was run, not to any sub-packages involved.

14.4 Checking the Distribution
==============================

Automake also generates a 'distcheck' rule that can be of help to ensure
that a given distribution will actually work.  Simplifying a bit, we can
say this rule first makes a distribution, and then, _operating from it_,
takes the following steps:
   * tries to do a 'VPATH' build (*note VPATH Builds::), with the
     'srcdir' and all its content made _read-only_;
   * runs the test suite (with 'make check') on this fresh build;
   * installs the package in a temporary directory (with 'make
     install'), and tries runs the test suite on the resulting
     installation (with 'make installcheck');
   * checks that the package can be correctly uninstalled (by 'make
     uninstall') and cleaned (by 'make distclean');
   * finally, makes another tarball to ensure the distribution is
     self-contained.

DISTCHECK_CONFIGURE_FLAGS
-------------------------

Building the package involves running './configure'.  If you need to
supply additional flags to 'configure', define them in the
'AM_DISTCHECK_CONFIGURE_FLAGS' variable in your top-level 'Makefile.am'.
The user can still extend or override the flags provided there by
defining the 'DISTCHECK_CONFIGURE_FLAGS' variable, on the command line
when invoking 'make'.  It's worth nothing that 'make distcheck' needs
complete control over the 'configure' options '--srcdir' and '--prefix',
so those options cannot be overridden by 'AM_DISTCHECK_CONFIGURE_FLAGS'
nor by 'DISTCHECK_CONFIGURE_FLAGS'.

   Also note that developers are encouraged to strive to make their code
buildable without requiring any special configure option; thus, in
general, you shouldn't define 'AM_DISTCHECK_CONFIGURE_FLAGS'.  However,
there might be few scenarios in which the use of this variable is
justified.  GNU 'm4' offers an example.  GNU 'm4' configures by default
with its experimental and seldom used "changeword" feature disabled; so
in its case it is useful to have 'make distcheck' run configure with the
'--with-changeword' option, to ensure that the code for changeword
support still compiles correctly.  GNU 'm4' also employs the
'AM_DISTCHECK_CONFIGURE_FLAGS' variable to stress-test the use of
'--program-prefix=g', since at one point the 'm4' build system had a bug
where 'make installcheck' was wrongly assuming it could blindly test
"'m4'", rather than the just-installed "'gm4'".

distcheck-hook
--------------

If the 'distcheck-hook' rule is defined in your top-level 'Makefile.am',
then it will be invoked by 'distcheck' after the new distribution has
been unpacked, but before the unpacked copy is configured and built.
Your 'distcheck-hook' can do almost anything, though as always caution
is advised.  Generally this hook is used to check for potential
distribution errors not caught by the standard mechanism.  Note that
'distcheck-hook' as well as 'AM_DISTCHECK_CONFIGURE_FLAGS' and
'DISTCHECK_CONFIGURE_FLAGS' are not honored in a subpackage
'Makefile.am', but the flags from 'AM_DISTCHECK_CONFIGURE_FLAGS' and
'DISTCHECK_CONFIGURE_FLAGS' are passed down to the 'configure' script of
the subpackage.

distcleancheck
--------------

Speaking of potential distribution errors, 'distcheck' also ensures that
the 'distclean' rule actually removes all built files.  This is done by
running 'make distcleancheck' at the end of the 'VPATH' build.  By
default, 'distcleancheck' will run 'distclean' and then make sure the
build tree has been emptied by running '$(distcleancheck_listfiles)'.
Usually this check will find generated files that you forgot to add to
the 'DISTCLEANFILES' variable (*note Clean::).

   The 'distcleancheck' behavior should be OK for most packages,
otherwise you have the possibility to override the definition of either
the 'distcleancheck' rule, or the '$(distcleancheck_listfiles)'
variable.  For instance, to disable 'distcleancheck' completely, add the
following rule to your top-level 'Makefile.am':

     distcleancheck:
             @:

   If you want 'distcleancheck' to ignore built files that have not been
cleaned because they are also part of the distribution, add the
following definition instead:

     distcleancheck_listfiles = 
       find . -type f -exec sh -c 'test -f $(srcdir)/$$1 || echo $$1' 
            sh '{}' ';'

   The above definition is not the default because it's usually an error
if your Makefiles cause some distributed files to be rebuilt when the
user build the package.  (Think about the user missing the tool required
to build the file; or if the required tool is built by your package,
consider the cross-compilation case where it can't be run.)  There is an
entry in the FAQ about this (*note Errors with distclean::), make sure
you read it before playing with 'distcleancheck_listfiles'.

distuninstallcheck
------------------

'distcheck' also checks that the 'uninstall' rule works properly, both
for ordinary and 'DESTDIR' builds.  It does this by invoking 'make
uninstall', and then it checks the install tree to see if any files are
left over.  This check will make sure that you correctly coded your
'uninstall'-related rules.

   By default, the checking is done by the 'distuninstallcheck' rule,
and the list of files in the install tree is generated by
'$(distuninstallcheck_listfiles)' (this is a variable whose value is a
shell command to run that prints the list of files to stdout).

   Either of these can be overridden to modify the behavior of
'distcheck'.  For instance, to disable this check completely, you would
write:

     distuninstallcheck:
             @:

14.5 The Types of Distributions
===============================

Automake generates rules to provide archives of the project for
distributions in various formats.  Their targets are:

'dist-gzip'
     Generate a 'gzip' tar archive of the distribution.  This is the
     only format enabled by default.

'dist-bzip2'
     Generate a 'bzip2' tar archive of the distribution.  bzip2 archives
     are frequently smaller than gzipped archives.  By default, this
     rule makes 'bzip2' use a compression option of '-9'.  To make it
     use a different one, set the 'BZIP2' environment variable.  For
     example, 'make dist-bzip2 BZIP2=-7'.

'dist-lzip'
     Generate an 'lzip' tar archive of the distribution.  'lzip'
     archives are frequently smaller than 'bzip2'-compressed archives.

'dist-xz'
     Generate an 'xz' tar archive of the distribution.  'xz' archives
     are frequently smaller than 'bzip2'-compressed archives.  By
     default, this rule makes 'xz' use a compression option of '-e'.  To
     make it use a different one, set the 'XZ_OPT' environment variable.
     For example, run this command to use the default compression ratio,
     but with a progress indicator: 'make dist-xz XZ_OPT=-ve'.

'dist-zip'
     Generate a 'zip' archive of the distribution.

'dist-tarZ'
     Generate a tar archive of the distribution, compressed with the
     historical (and obsolescent) program 'compress'.  This option is
     deprecated, and it and the corresponding functionality will be
     removed altogether in Automake 2.0.

'dist-shar'
     Generate a 'shar' archive of the distribution.  This format archive
     is obsolescent, and use of this option is deprecated.  It and the
     corresponding functionality will be removed altogether in Automake
     2.0.

   The rule 'dist' (and its historical synonym 'dist-all') will create
archives in all the enabled formats (*note List of Automake options::
for how to change this list).  By default, only the 'dist-gzip' target
is hooked to 'dist'.

15 Support for test suites
**************************

Automake can generate code to handle two kinds of test suites.  One is
based on integration with the 'dejagnu' framework.  The other (and most
used) form is based on the use of generic test scripts, and its
activation is triggered by the definition of the special 'TESTS'
variable.  This second form allows for various degrees of sophistication
and customization; in particular, it allows for concurrent execution of
test scripts, use of established test protocols such as TAP, and
definition of custom test drivers and test runners.

In either case, the testsuite is invoked via 'make check'.

15.1 Generalities about Testing
===============================

The purpose of testing is to determine whether a program or system
behaves as expected (e.g., known inputs produce the expected outputs,
error conditions are correctly handled or reported, and older bugs do
not resurface).

   The minimal unit of testing is usually called _test case_, or simply
_test_.  How a test case is defined or delimited, and even what exactly
_constitutes_ a test case, depends heavily on the testing paradigm
and/or framework in use, so we won't attempt any more precise
definition.  The set of the test cases for a given program or system
constitutes its _testsuite_.

   A _test harness_ (also _testsuite harness_) is a program or software
component that executes all (or part of) the defined test cases,
analyzes their outcomes, and report or register these outcomes
appropriately.  Again, the details of how this is accomplished (and how
the developer and user can influence it or interface with it) varies
wildly, and we'll attempt no precise definition.

   A test is said to _pass_ when it can determine that the condition or
behaviour it means to verify holds, and is said to _fail_ when it can
determine that such condition of behaviour does _not_ hold.

   Sometimes, tests can rely on non-portable tools or prerequisites, or
simply make no sense on a given system (for example, a test checking a
Windows-specific feature makes no sense on a GNU/Linux system).  In this
case, accordingly to the definition above, the tests can neither be
considered passed nor failed; instead, they are _skipped_ - i.e., they
are not run, or their result is anyway ignored for what concerns the
count of failures an successes.  Skips are usually explicitly reported
though, so that the user will be aware that not all of the testsuite has
really run.

   It's not uncommon, especially during early development stages, that
some tests fail for known reasons, and that the developer doesn't want
to tackle these failures immediately (this is especially true when the
failing tests deal with corner cases).  In this situation, the better
policy is to declare that each of those failures is an _expected
failure_ (or _xfail_).  In case a test that is expected to fail ends up
passing instead, many testing environments will flag the result as a
special kind of failure called _unexpected pass_ (or _xpass_).

   Many testing environments and frameworks distinguish between test
failures and hard errors.  As we've seen, a test failure happens when
some invariant or expected behaviour of the software under test is not
met.  An _hard error_ happens when e.g., the set-up of a test case
scenario fails, or when some other unexpected or highly undesirable
condition is encountered (for example, the program under test
experiences a segmentation fault).

   _TODO_: Links to other test harnesses (esp.  those sharing our
terminology)?

15.2 Simple Tests
=================

15.2.1 Scripts-based Testsuites
-------------------------------

If the special variable 'TESTS' is defined, its value is taken to be a
list of programs or scripts to run in order to do the testing.  Under
the appropriate circumstances, it's possible for 'TESTS' to list also
data files to be passed to one or more test scripts defined by different
means (the so-called "log compilers", *note Parallel Test Harness::).

   Test scripts can be executed serially or concurrently.  Automake
supports both these kinds of test execution, with the parallel test
harness being the default.  The concurrent test harness relies on the
concurrence capabilities (if any) offered by the underlying 'make'
implementation, and can thus only be as good as those are.

   By default, only the exit statuses of the test scripts are considered
when determining the testsuite outcome.  But Automake allows also the
use of more complex test protocols, either standard (*note Using the TAP
test protocol::) or custom (*note Custom Test Drivers::).  Note that you
can't enable such protocols when the serial harness is used, though.  In
the rest of this section we are going to concentrate mostly on
protocol-less tests, since we cover test protocols in a later section
(again, *note Custom Test Drivers::).

   When no test protocol is in use, an exit status of 0 from a test
script will denote a success, an exit status of 77 a skipped test, an
exit status of 99 an hard error, and any other exit status will denote a
failure.

   You may define the variable 'XFAIL_TESTS' to a list of tests (usually
a subset of 'TESTS') that are expected to fail; this will effectively
reverse the result of those tests (with the provision that skips and
hard errors remain untouched).  You may also instruct the testsuite
harness to treat hard errors like simple failures, by defining the
'DISABLE_HARD_ERRORS' make variable to a nonempty value.

   Note however that, for tests based on more complex test protocols,
the exact effects of 'XFAIL_TESTS' and 'DISABLE_HARD_ERRORS' might
change, or they might even have no effect at all (for example, in tests
using TAP, there is not way to disable hard errors, and the
'DISABLE_HARD_ERRORS' variable has no effect on them).

   The result of each test case run by the scripts in 'TESTS' will be
printed on standard output, along with the test name.  For test
protocols that allow more test cases per test script (such as TAP), a
number, identifier and/or brief description specific for the single test
case is expected to be printed in addition to the name of the test
script.  The possible results (whose meanings should be clear from the
previous *note Generalities about Testing::) are 'PASS', 'FAIL', 'SKIP',
'XFAIL', 'XPASS' and 'ERROR'.  Here is an example of output from an
hypothetical testsuite that uses both plain and TAP tests:
     PASS: foo.sh
     PASS: zardoz.tap 1 - Daemon started
     PASS: zardoz.tap 2 - Daemon responding
     SKIP: zardoz.tap 3 - Daemon uses /proc # SKIP /proc is not mounted
     PASS: zardoz.tap 4 - Daemon stopped
     SKIP: bar.sh
     PASS: mu.tap 1
     XFAIL: mu.tap 2 # TODO frobnication not yet implemented

A testsuite summary (expected to report at least the number of run,
skipped and failed tests) will be printed at the end of the testsuite
run.

   If the standard output is connected to a capable terminal, then the
test results and the summary are colored appropriately.  The developer
and the user can disable colored output by setting the 'make' variable
'AM_COLOR_TESTS=no'; the user can in addition force colored output even
without a connecting terminal with 'AM_COLOR_TESTS=always'.  It's also
worth noting that some 'make' implementations, when used in parallel
mode, have slightly different semantics (*note (autoconf)Parallel
make::), which can break the automatic detection of a connection to a
capable terminal.  If this is the case, the user will have to resort to
the use of 'AM_COLOR_TESTS=always' in order to have the testsuite output
colorized.

   Test programs that need data files should look for them in 'srcdir'
(which is both a make variable and an environment variable made
available to the tests), so that they work when building in a separate
directory (*note Build Directories: (autoconf)Build Directories.), and
in particular for the 'distcheck' rule (*note Checking the
Distribution::).

   The 'AM_TESTS_ENVIRONMENT' and 'TESTS_ENVIRONMENT' variables can be
used to run initialization code and set environment variables for the
test scripts.  The former variable is developer-reserved, and can be
defined in the 'Makefile.am', while the latter is reserved for the user,
which can employ it to extend or override the settings in the former;
for this to work portably, however, the contents of a non-empty
'AM_TESTS_ENVIRONMENT' _must_ be terminated by a semicolon.

   The 'AM_TESTS_FD_REDIRECT' variable can be used to define file
descriptor redirections for the test scripts.  One might think that
'AM_TESTS_ENVIRONMENT' could be used for this purpose, but experience
has shown that doing so portably is practically impossible.  The main
hurdle is constituted by Korn shells, which usually set the
close-on-exec flag on file descriptors opened with the 'exec' builtin,
thus rendering an idiom like 'AM_TESTS_ENVIRONMENT = exec 9>&2;'
ineffectual.  This issue also affects some Bourne shells, such as the
HP-UX's '/bin/sh',

     AM_TESTS_ENVIRONMENT = 
     ## Some environment initializations are kept in a separate shell
     ## file 'tests-env.sh', which can make it easier to also run tests
     ## from the command line.
       . $(srcdir)/tests-env.sh; 
     ## On Solaris, prefer more POSIX-compliant versions of the standard
     ## tools by default.
       if test -d /usr/xpg4/bin; then 
         PATH=/usr/xpg4/bin:$$PATH; export PATH; 
       fi;
     ## With this, the test scripts will be able to print diagnostic
     ## messages to the original standard error stream, even if the test
     ## driver redirects the stderr of the test scripts to a log file
     ## before executing them.
     AM_TESTS_FD_REDIRECT = 9>&2

Note however that 'AM_TESTS_ENVIRONMENT' is, for historical and
implementation reasons, _not_ supported by the serial harness (*note
Serial Test Harness::).

   Automake ensures that each file listed in 'TESTS' is built before it
is run; you can list both source and derived programs (or scripts) in
'TESTS'; the generated rule will look both in 'srcdir' and '.'.  For
instance, you might want to run a C program as a test.  To do this you
would list its name in 'TESTS' and also in 'check_PROGRAMS', and then
specify it as you would any other program.

   Programs listed in 'check_PROGRAMS' (and 'check_LIBRARIES',
'check_LTLIBRARIES'...)  are only built during 'make check', not during
'make all'.  You should list there any program needed by your tests that
does not need to be built by 'make all'.  Note that 'check_PROGRAMS' are
_not_ automatically added to 'TESTS' because 'check_PROGRAMS' usually
lists programs used by the tests, not the tests themselves.  Of course
you can set 'TESTS = $(check_PROGRAMS)' if all your programs are test
cases.

15.2.2 Older (and discouraged) serial test harness
--------------------------------------------------

First, note that today the use of this harness is strongly discouraged
in favour of the parallel test harness (*note Parallel Test Harness::).
Still, there are _few_ situations when the advantages offered by the
parallel harness are irrelevant, and when test concurrency can even
cause tricky problems.  In those cases, it might make sense to still use
the serial harness, for simplicity and reliability (we still suggest
trying to give the parallel harness a shot though).

   The serial test harness is enabled by the Automake option
'serial-tests'.  It operates by simply running the tests serially, one
at the time, without any I/O redirection.  It's up to the user to
implement logging of tests' output, if that's requited or desired.

   For historical and implementation reasons, the 'AM_TESTS_ENVIRONMENT'
variable is _not_ supported by this harness (it will be silently ignored
if defined); only 'TESTS_ENVIRONMENT' is, and it is to be considered a
developer-reserved variable.  This is done so that, when using the
serial harness, 'TESTS_ENVIRONMENT' can be defined to an invocation of
an interpreter through which the tests are to be run.  For instance, the
following setup may be used to run tests with Perl:

     TESTS_ENVIRONMENT = $(PERL) -Mstrict -w
     TESTS = foo.pl bar.pl baz.pl

It's important to note that the use of 'TESTS_ENVIRONMENT' endorsed here
would be _invalid_ with the parallel harness.  That harness provides a
more elegant way to achieve the same effect, with the further benefit of
freeing the 'TESTS_ENVIRONMENT' variable for the user (*note Parallel
Test Harness::).

   Another, less serious limit of the serial harness is that it doesn't
really distinguish between simple failures and hard errors; this is due
to historical reasons only, and might be fixed in future Automake
versions.

15.2.3 Parallel Test Harness
----------------------------

By default, Automake generated a parallel (concurrent) test harness.  It
features automatic collection of the test scripts output in '.log'
files, concurrent execution of tests with 'make -j', specification of
inter-test dependencies, lazy reruns of tests that have not completed in
a prior run, and hard errors for exceptional failures.

   The parallel test harness operates by defining a set of 'make' rules
that run the test scripts listed in 'TESTS', and, for each such script,
save its output in a corresponding '.log' file and its results (and
other "metadata", *note API for Custom Test Drivers::) in a
corresponding '.trs' (as in Test ReSults) file.  The '.log' file will
contain all the output emitted by the test on its standard output and
its standard error.  The '.trs' file will contain, among the other
things, the results of the test cases run by the script.

   The parallel test harness will also create a summary log file,
'TEST_SUITE_LOG', which defaults to 'test-suite.log' and requires a
'.log' suffix.  This file depends upon all the '.log' and '.trs' files
created for the test scripts listed in 'TESTS'.

   As with the serial harness above, by default one status line is
printed per completed test, and a short summary after the suite has
completed.  However, standard output and standard error of the test are
redirected to a per-test log file, so that parallel execution does not
produce intermingled output.  The output from failed tests is collected
in the 'test-suite.log' file.  If the variable 'VERBOSE' is set, this
file is output after the summary.  For best results, the tests should be
verbose by default now.

   Each couple of '.log' and '.trs' files is created when the
corresponding test has completed.  The set of log files is listed in the
read-only variable 'TEST_LOGS', and defaults to 'TESTS', with the
executable extension if any (*note EXEEXT::), as well as any suffix
listed in 'TEST_EXTENSIONS' removed, and '.log' appended.  Results are
undefined if a test file name ends in several concatenated suffixes.
'TEST_EXTENSIONS' defaults to '.test'; it can be overridden by the user,
in which case any extension listed in it must be constituted by a dot,
followed by a non-digit alphabetic character, followed by any number of
alphabetic characters.  For example, '.sh', '.T' and '.t1' are valid
extensions, while '.x-y', '.6c' and '.t.1' are not.

   It is important to note that, due to current limitations (unlikely to
be lifted), configure substitutions in the definition of 'TESTS' can
only work if they will expand to a list of tests that have a suffix
listed in 'TEST_EXTENSIONS'.

   For tests that match an extension '.EXT' listed in 'TEST_EXTENSIONS',
you can provide a custom "test runner" using the variable
'EXT_LOG_COMPILER' (note the upper-case extension) and pass options in
'AM_EXT_LOG_FLAGS' and allow the user to pass options in
'EXT_LOG_FLAGS'.  It will cause all tests with this extension to be
called with this runner.  For all tests without a registered extension,
the variables 'LOG_COMPILER', 'AM_LOG_FLAGS', and 'LOG_FLAGS' may be
used.  For example,

     TESTS = foo.pl bar.py baz
     TEST_EXTENSIONS = .pl .py
     PL_LOG_COMPILER = $(PERL)
     AM_PL_LOG_FLAGS = -w
     PY_LOG_COMPILER = $(PYTHON)
     AM_PY_LOG_FLAGS = -v
     LOG_COMPILER = ./wrapper-script
     AM_LOG_FLAGS = -d

will invoke '$(PERL) -w foo.pl', '$(PYTHON) -v bar.py', and
'./wrapper-script -d baz' to produce 'foo.log', 'bar.log', and
'baz.log', respectively.  The 'foo.trs', 'bar.trs' and 'baz.trs' files
will be automatically produced as a side-effect.

   It's important to note that, differently from what we've seen for the
serial test harness (*note Parallel Test Harness::), the
'AM_TESTS_ENVIRONMENT' and 'TESTS_ENVIRONMENT' variables _cannot_ be use
to define a custom test runner; the 'LOG_COMPILER' and 'LOG_FLAGS' (or
their extension-specific counterparts) should be used instead:

     ## This is WRONG!
     AM_TESTS_ENVIRONMENT = PERL5LIB='$(srcdir)/lib' $(PERL) -Mstrict -w

     ## Do this instead.
     AM_TESTS_ENVIRONMENT = PERL5LIB='$(srcdir)/lib'; export PERL5LIB;
     LOG_COMPILER = $(PERL)
     AM_LOG_FLAGS = -Mstrict -w

   By default, the test suite harness will run all tests, but there are
several ways to limit the set of tests that are run:

   * You can set the 'TESTS' variable.  For example, you can use a
     command like this to run only a subset of the tests:

          env TESTS="foo.test bar.test" make -e check

     Note however that the command above will unconditionally overwrite
     the 'test-suite.log' file, thus clobbering the recorded results of
     any previous testsuite run.  This might be undesirable for packages
     whose testsuite takes long time to execute.  Luckily, this problem
     can easily be avoided by overriding also 'TEST_SUITE_LOG' at
     runtime; for example,

          env TEST_SUITE_LOG=partial.log TESTS="..." make -e check

     will write the result of the partial testsuite runs to the
     'partial.log', without touching 'test-suite.log'.

   * You can set the 'TEST_LOGS' variable.  By default, this variable is
     computed at 'make' run time from the value of 'TESTS' as described
     above.  For example, you can use the following:

          set x subset*.log; shift
          env TEST_LOGS="foo.log $*" make -e check

     The comments made above about 'TEST_SUITE_LOG' overriding applies
     here too.

   * By default, the test harness removes all old per-test '.log' and
     '.trs' files before it starts running tests to regenerate them.
     The variable 'RECHECK_LOGS' contains the set of '.log' (and, by
     implication, '.trs') files which are removed.  'RECHECK_LOGS'
     defaults to 'TEST_LOGS', which means all tests need to be
     rechecked.  By overriding this variable, you can choose which tests
     need to be reconsidered.  For example, you can lazily rerun only
     those tests which are outdated, i.e., older than their prerequisite
     test files, by setting this variable to the empty value:

          env RECHECK_LOGS= make -e check

   * You can ensure that all tests are rerun which have failed or passed
     unexpectedly, by running 'make recheck' in the test directory.
     This convenience target will set 'RECHECK_LOGS' appropriately
     before invoking the main test harness.

In order to guarantee an ordering between tests even with 'make -jN',
dependencies between the corresponding '.log' files may be specified
through usual 'make' dependencies.  For example, the following snippet
lets the test named 'foo-execute.test' depend upon completion of the
test 'foo-compile.test':

     TESTS = foo-compile.test foo-execute.test
     foo-execute.log: foo-compile.log

Please note that this ordering ignores the _results_ of required tests,
thus the test 'foo-execute.test' is run even if the test
'foo-compile.test' failed or was skipped beforehand.  Further, please
note that specifying such dependencies currently works only for tests
that end in one of the suffixes listed in 'TEST_EXTENSIONS'.

   Tests without such specified dependencies may be run concurrently
with parallel 'make -jN', so be sure they are prepared for concurrent
execution.

   The combination of lazy test execution and correct dependencies
between tests and their sources may be exploited for efficient unit
testing during development.  To further speed up the edit-compile-test
cycle, it may even be useful to specify compiled programs in
'EXTRA_PROGRAMS' instead of with 'check_PROGRAMS', as the former allows
intertwined compilation and test execution (but note that
'EXTRA_PROGRAMS' are not cleaned automatically, *note Uniform::).

   The variables 'TESTS' and 'XFAIL_TESTS' may contain conditional parts
as well as configure substitutions.  In the latter case, however,
certain restrictions apply: substituted test names must end with a
nonempty test suffix like '.test', so that one of the inference rules
generated by 'automake' can apply.  For literal test names, 'automake'
can generate per-target rules to avoid this limitation.

   Please note that it is currently not possible to use '$(srcdir)/' or
'$(top_srcdir)/' in the 'TESTS' variable.  This technical limitation is
necessary to avoid generating test logs in the source tree and has the
unfortunate consequence that it is not possible to specify distributed
tests that are themselves generated by means of explicit rules, in a way
that is portable to all 'make' implementations (*note (autoconf)Make
Target Lookup::, the semantics of FreeBSD and OpenBSD 'make' conflict
with this).  In case of doubt you may want to require to use GNU 'make',
or work around the issue with inference rules to generate the tests.

15.3 Custom Test Drivers
========================

15.3.1 Overview of Custom Test Drivers Support
----------------------------------------------

Starting from Automake version 1.12, the parallel test harness allows
the package authors to use third-party custom test drivers, in case the
default ones are inadequate for their purposes, or do not support their
testing protocol of choice.

   A custom test driver is expected to properly run the test programs
passed to it (including the command-line arguments passed to those
programs, if any), to analyze their execution and outcome, to create the
'.log' and '.trs' files associated to these test runs, and to display
the test results on the console.  It is responsibility of the author of
the test driver to ensure that it implements all the above steps
meaningfully and correctly; Automake isn't and can't be of any help
here.  On the other hand, the Automake-provided code for testsuite
summary generation offers support for test drivers allowing several test
results per test script, if they take care to register such results
properly (*note Log files generation and test results recording::).

   The exact details of how test scripts' results are to be determined
and analyzed is left to the individual drivers.  Some drivers might only
consider the test script exit status (this is done for example by the
default test driver used by the parallel test harness, described in the
previous section).  Other drivers might implement more complex and
advanced test protocols, which might require them to parse and
interpreter the output emitted by the test script they're running
(examples of such protocols are TAP and SubUnit).

   It's very important to note that, even when using custom test
drivers, most of the infrastructure described in the previous section
about the parallel harness remains in place; this includes:

   * list of test scripts defined in 'TESTS', and overridable at runtime
     through the redefinition of 'TESTS' or 'TEST_LOGS';
   * concurrency through the use of 'make''s option '-j';
   * per-test '.log' and '.trs' files, and generation of a summary
     '.log' file from them;
   * 'recheck' target, 'RECHECK_LOGS' variable, and lazy reruns of
     tests;
   * inter-test dependencies;
   * support for 'check_*' variables ('check_PROGRAMS',
     'check_LIBRARIES', ...);
   * use of 'VERBOSE' environment variable to get verbose output on
     testsuite failures;
   * definition and honoring of 'TESTS_ENVIRONMENT',
     'AM_TESTS_ENVIRONMENT' and 'AM_TESTS_FD_REDIRECT' variables;
   * definition of generic and extension-specific 'LOG_COMPILER' and
     'LOG_FLAGS' variables.

On the other hand, the exact semantics of how (and if) testsuite output
colorization, 'XFAIL_TESTS', and hard errors are supported and handled
is left to the individual test drivers.

15.3.2 Declaring Custom Test Drivers
------------------------------------

Custom testsuite drivers are declared by defining the make variables
'LOG_DRIVER' or 'EXT_LOG_DRIVER' (where EXT must be declared in
'TEST_EXTENSIONS').  They must be defined to programs or scripts that
will be used to drive the execution, logging, and outcome report of the
tests with corresponding extensions (or of those with no registered
extension in the case of 'LOG_DRIVER').  Clearly, multiple distinct test
drivers can be declared in the same 'Makefile.am'.  Note moreover that
the 'LOG_DRIVER' variables are _not_ a substitute for the 'LOG_COMPILER'
variables: the two sets of variables can, and often do, usefully and
legitimately coexist.

   The developer-reserved variable 'AM_LOG_DRIVER_FLAGS' and the
user-reserved variable 'LOG_DRIVER_FLAGS' can be used to define flags
that will be passed to each invocation of 'LOG_DRIVER', with the
user-defined flags obviously taking precedence over the
developer-reserved ones.  Similarly, for each extension EXT declared in
'TEST_EXTENSIONS', flags listed in 'AM_EXT_LOG_DRIVER_FLAGS' and
'EXT_LOG_DRIVER_FLAGS' will be passed to invocations of
'EXT_LOG_DRIVER'.

15.3.3 API for Custom Test Drivers
----------------------------------

Note that _the APIs described here are still highly experimental_, and
will very likely undergo tightenings and likely also extensive changes
in the future, to accommodate for new features or to satisfy additional
portability requirements.

   The main characteristic of these APIs is that they are designed to
share as much infrastructure, semantics, and implementation details as
possible with the parallel test harness and its default driver.

15.3.3.1 Command-line arguments for test drivers
................................................

A custom driver can rely on various command-line options and arguments
being passed to it automatically by the Automake-generated test harness.
It is _mandatory_ that it understands all of them (even if the exact
interpretation of the associated semantics can legitimately change
between a test driver and another, and even be a no-op in some drivers).

Here is the list of options:

'--test-name=NAME'
     The name of the test, with VPATH prefix (if any) removed.  This can
     have a suffix and a directory component (as in e.g.,
     'sub/foo.test'), and is mostly meant to be used in console reports
     about testsuite advancements and results (*note Testsuite progress
     output::).
'--log-file=PATH.log'
     The '.log' file the test driver must create (*note Basics of test
     metadata::).  If it has a directory component (as in e.g.,
     'sub/foo.log'), the test harness will ensure that such directory
     exists _before_ the test driver is called.
'--trs-file=PATH.trs'
     The '.trs' file the test driver must create (*note Basics of test
     metadata::).  If it has a directory component (as in e.g.,
     'sub/foo.trs'), the test harness will ensure that such directory
     exists _before_ the test driver is called.
'--color-tests={yes|no}'
     Whether the console output should be colorized or not (*note Simple
     tests and color-tests::, to learn when this option gets activated
     and when it doesn't).
'--expect-failure={yes|no}'
     Whether the tested program is expected to fail.
'--enable-hard-errors={yes|no}'
     Whether "hard errors" in the tested program should be treated
     differently from normal failures or not (the default should be
     'yes').  The exact meaning of "hard error" is highly dependent from
     the test protocols or conventions in use.
'--'
     Explicitly terminate the list of options.

The first non-option argument passed to the test driver is the program
to be run, and all the following ones are command-line options and
arguments for this program.

   Note that the exact semantics attached to the '--color-tests',
'--expect-failure' and '--enable-hard-errors' options are left up to the
individual test drivers.  Still, having a behaviour compatible or at
least similar to that provided by the default driver is advised, as that
would offer a better consistency and a more pleasant user experience.

15.3.3.2 Log files generation and test results recording
........................................................

The test driver must correctly generate the files specified by the
'--log-file' and '--trs-file' option (even when the tested program fails
or crashes).

   The '.log' file should ideally contain all the output produced by the
tested program, plus optionally other information that might facilitate
debugging or analysis of bug reports.  Apart from that, its format is
basically free.

   The '.trs' file is used to register some metadata through the use of
custom reStructuredText fields.  This metadata is expected to be
employed in various ways by the parallel test harness; for example, to
count the test results when printing the testsuite summary, or to decide
which tests to re-run upon 'make reheck'.  Unrecognized metadata in a
'.trs' file is currently ignored by the harness, but this might change
in the future.  The list of currently recognized metadata follows.

':test-result:'
     The test driver must use this field to register the results of
     _each_ test case run by a test script file.  Several
     ':test-result:' fields can be present in the same '.trs' file; this
     is done in order to support test protocols that allow a single test
     script to run more test cases.

     The only recognized test results are currently 'PASS', 'XFAIL',
     'SKIP', 'FAIL', 'XPASS' and 'ERROR'.  These results, when declared
     with ':test-result:', can be optionally followed by text holding
     the name and/or a brief description of the corresponding test; the
     harness will ignore such extra text when generating
     'test-suite.log' and preparing the testsuite summary.

':recheck:'
     If this field is present and defined to 'no', then the
     corresponding test script will _not_ be run upon a 'make recheck'.
     What happens when two or more ':recheck:' fields are present in the
     same '.trs' file is undefined behaviour.

':copy-in-global-log:'
     If this field is present and defined to 'no', then the content of
     the '.log' file will _not_ be copied into the global
     'test-suite.log'.  We allow to forsake such copying because, while
     it can be useful in debugging and analysis of bug report, it can
     also be just a waste of space in normal situations, e.g., when a
     test script is successful.  What happens when two or more
     ':copy-in-global-log:' fields are present in the same '.trs' file
     is undefined behaviour.

':test-global-result:'
     This is used to declare the "global result" of the script.
     Currently, the value of this field is needed only to be reported
     (more or less verbatim) in the generated global log file
     '$(TEST_SUITE_LOG)', so it's quite free-form.  For example, a test
     script which run 10 test cases, 6 of which pass and 4 of which are
     skipped, could reasonably have a 'PASS/SKIP' value for this field,
     while a test script which run 19 successful tests and one failed
     test could have an 'ALMOST PASSED' value.  What happens when two or
     more ':test-global-result:' fields are present in the same '.trs'
     file is undefined behaviour.

Let's see a small example.  Assume a '.trs' file contains the following
lines:

     :test-result: PASS server starts
     :global-log-copy: no
     :test-result: PASS HTTP/1.1 request
     :test-result: FAIL HTTP/1.0 request
     :recheck: yes
     :test-result: SKIP HTTPS request (TLS library wasn't available)
     :test-result: PASS server stops

Then the corresponding test script will be re-run by 'make check', will
contribute with _five_ test results to the testsuite summary (three of
these tests being successful, one failed, and one skipped), and the
content of the corresponding '.log' file will _not_ be copied in the
global log file 'test-suite.log'.

15.3.3.3 Testsuite progress output
..................................

A custom test driver also has the task of displaying, on the standard
output, the test results as soon as they become available.  Depending on
the protocol in use, it can also display the reasons for failures and
skips, and, more generally, any useful diagnostic output (but remember
that each line on the screen is precious, so that cluttering the screen
with overly verbose information is bad idea).  The exact format of this
progress output is left up to the test driver; in fact, a custom test
driver might _theoretically_ even decide not to do any such report,
leaving it all to the testsuite summary (that would be a very lousy
idea, of course, and serves only to illustrate the flexibility that is
granted here).

   Remember that consistency is good; so, if possible, try to be
consistent with the output of the built-in Automake test drivers,
providing a similar "look & feel".  In particular, the testsuite
progress output should be colorized when the '--color-tests' is passed
to the driver.  On the other end, if you are using a known and
widespread test protocol with well-established implementations, being
consistent with those implementations' output might be a good idea too.

15.4 Using the TAP test protocol
================================

15.4.1 Introduction to TAP
--------------------------

TAP, the Test Anything Protocol, is a simple text-based interface
between testing modules or programs and a test harness.  The tests (also
called "TAP producers" in this context) write test results in a simple
format on standard output; a test harness (also called "TAP consumer")
will parse and interpret these results, and properly present them to the
user, and/or register them for later analysis.  The exact details of how
this is accomplished can vary among different test harnesses.  The
Automake harness will present the results on the console in the usual
fashion (*note Testsuite progress on console::), and will use the '.trs'
files (*note Basics of test metadata::) to store the test results and
related metadata.  Apart from that, it will try to remain as much
compatible as possible with pre-existing and widespread utilities, such
as the 'prove' utility
(http://search.cpan.org/~andya/Test-Harness/bin/prove), at least for the
simpler usages.

   TAP started its life as part of the test harness for Perl, but today
it has been (mostly) standardized, and has various independent
implementations in different languages; among them, C, C++, Perl,
Python, PHP, and Java.  For a semi-official specification of the TAP
protocol, please refer to the documentation of 'Test::Harness::TAP'
(http://search.cpan.org/~petdance/Test-Harness/lib/Test/Harness/TAP.pod).

   The most relevant real-world usages of TAP are obviously in the
testsuites of 'perl' and of many perl modules.  Still, also other
important third-party packages, such as 'git' (http://git-scm.com/), use
TAP in their testsuite.

15.4.2 Use TAP with the Automake test harness
---------------------------------------------

Currently, the TAP driver that comes with Automake requires some by-hand
steps on the developer's part (this situation should hopefully be
improved in future Automake versions).  You'll have to grab the
'tap-driver.sh' script from the Automake distribution by hand, copy it
in your source tree, add a call to 'AC_PROG_AWK' in 'configure.ac' to
search for a proper awk program, and use the Automake support for
third-party test drivers to instruct the harness to use the
'tap-driver.sh' script and that awk program to run your TAP-producing
tests.  See the example below for clarification.

   Apart from the options common to all the Automake test drivers (*note
Command-line arguments for test drivers::), the 'tap-driver.sh' supports
the following options, whose names are chosen for enhanced compatibility
with the 'prove' utility.

'--ignore-exit'
     Causes the test driver to ignore the exit status of the test
     scripts; by default, the driver will report an error if the script
     exits with a non-zero status.  This option has effect also on
     non-zero exit statuses due to termination by a signal.
'--comments'
     Instruct the test driver to display TAP diagnostic (i.e., lines
     beginning with the '#' character) in the testsuite progress output
     too; by default, TAP diagnostic is only copied to the '.log' file.
'--no-comments'
     Revert the effects of '--comments'.
'--merge'
     Instruct the test driver to merge the test scripts' standard error
     into their standard output.  This is necessary if you want to
     ensure that diagnostics from the test scripts are displayed in the
     correct order relative to test results; this can be of great help
     in debugging (especially if your test scripts are shell scripts run
     with shell tracing active).  As a downside, this option might cause
     the test harness to get confused if anything that appears on
     standard error looks like a test result.
'--no-merge'
     Revert the effects of '--merge'.
'--diagnostic-string=STRING'
     Change the string that introduces TAP diagnostic from the default
     value of "'#'" to 'STRING'.  This can be useful if your TAP-based
     test scripts produce verbose output on which they have limited
     control (because, say, the output comes from other tools invoked in
     the scripts), and it might contain text that gets spuriously
     interpreted as TAP diagnostic: such an issue can be solved by
     redefining the string that activates TAP diagnostic to a value you
     know won't appear by chance in the tests' output.  Note however
     that this feature is non-standard, as the "official" TAP protocol
     does not allow for such a customization; so don't use it if you can
     avoid it.

Here is an example of how the TAP driver can be set up and used.

     % cat configure.ac
     AC_INIT([GNU Try Tap], [1.0], [bug-automake@gnu.org])
     AC_CONFIG_AUX_DIR([build-aux])
     AM_INIT_AUTOMAKE([foreign -Wall -Werror])
     AC_CONFIG_FILES([Makefile])
     AC_REQUIRE_AUX_FILE([tap-driver.sh])
     AC_PROG_AWK
     AC_OUTPUT

     % cat Makefile.am
     TEST_LOG_DRIVER = env AM_TAP_AWK='$(AWK)' $(SHELL) 
                       $(top_srcdir)/build-aux/tap-driver.sh
     TESTS = foo.test bar.test baz.test
     EXTRA_DIST = $(TESTS)

     % cat foo.test
     #!/bin/sh
     echo 1..4 # Number of tests to be executed.
     echo 'ok 1 - Swallows fly'
     echo 'not ok 2 - Caterpillars fly # TODO metamorphosis in progress'
     echo 'ok 3 - Pigs fly # SKIP not enough acid'
     echo '# I just love word plays ...'
     echo 'ok 4 - Flies fly too :-)'

     % cat bar.test
     #!/bin/sh
     echo 1..3
     echo 'not ok 1 - Bummer, this test has failed.'
     echo 'ok 2 - This passed though.'
     echo 'Bail out! Ennui kicking in, sorry...'
     echo 'ok 3 - This will not be seen.'

     % cat baz.test
     #!/bin/sh
     echo 1..1
     echo ok 1
     # Exit with error, even if all the tests have been successful.
     exit 7

     % cp PREFIX/share/automake-APIVERSION/tap-driver.pl .
     % autoreconf -vi && ./configure && make check
     ...
     PASS: foo.test 1 - Swallows fly
     XFAIL: foo.test 2 - Caterpillars fly # TODO metamorphosis in progress
     SKIP: foo.test 3 - Pigs fly # SKIP not enough acid
     PASS: foo.test 4 - Flies fly too :-)
     FAIL: bar.test 1 - Bummer, this test has failed.
     PASS: bar.test 2 - This passed though.
     ERROR: bar.test - Bail out! Ennui kicking in, sorry...
     PASS: baz.test 1
     ERROR: baz.test - exited with status 7
     ...
     Please report to bug-automake@gnu.org
     ...
     % echo exit status: $?
     exit status: 1

     % env TEST_LOG_DRIVER_FLAGS='--comments --ignore-exit' 
           TESTS='foo.test baz.test' make -e check
     ...
     PASS: foo.test 1 - Swallows fly
     XFAIL: foo.test 2 - Caterpillars fly # TODO metamorphosis in progress
     SKIP: foo.test 3 - Pigs fly # SKIP not enough acid
     # foo.test: I just love word plays...
     PASS: foo.test 4 - Flies fly too :-)
     PASS: baz.test 1
     ...
     % echo exit status: $?
     exit status: 0

15.4.3 Incompatibilities with other TAP parsers and drivers
-----------------------------------------------------------

For implementation or historical reasons, the TAP driver and harness as
implemented by Automake have some minors incompatibilities with the
mainstream versions, which you should be aware of.

   * A 'Bail out!' directive doesn't stop the whole testsuite, but only
     the test script it occurs in.  This doesn't follow TAP
     specifications, but on the other hand it maximizes compatibility
     (and code sharing) with the "hard error" concept of the default
     testsuite driver.
   * The 'version' and 'pragma' directives are not supported.
   * The '--diagnostic-string' option of our driver allows to modify the
     string that introduces TAP diagnostic from the default value of
     "'#'".  The standard TAP protocol has currently no way to allow
     this, so if you use it your diagnostic will be lost to more
     compliant tools like 'prove' and 'Test::Harness'
   * And there are probably some other small and yet undiscovered
     incompatibilities, especially in corner cases or with rare usages.

15.4.4 Links and external resources on TAP
------------------------------------------

Here are some links to more extensive official or third-party
documentation and resources about the TAP protocol and related tools and
libraries.
   *  'Test::Harness::TAP'
     (http://search.cpan.org/~petdance/Test-Harness/lib/Test/Harness/TAP.pod),
     the (mostly) official documentation about the TAP format and
     protocol.
   *  'prove' (http://search.cpan.org/~andya/Test-Harness/bin/prove),
     the most famous command-line TAP test driver, included in the
     distribution of 'perl' and 'Test::Harness'
     (http://search.cpan.org/~andya/Test-Harness/lib/Test/Harness.pm).
   * The TAP wiki (http://testanything.org/wiki/index.php/Main_Page).
   * A "gentle introduction" to testing for perl coders:
     'Test::Tutorial'
     (http://search.cpan.org/dist/Test-Simple/lib/Test/Tutorial.pod).
   *  'Test::Simple'
     (http://search.cpan.org/~mschwern/Test-Simple/lib/Test/Simple.pm)
     and 'Test::More'
     (http://search.cpan.org/~mschwern/Test-Simple/lib/Test/More.pm),
     the standard perl testing libraries, which are based on TAP.
   * C TAP Harness
     (http://www.eyrie.org/~eagle/software/c-tap-harness/), a C-based
     project implementing both a TAP producer and a TAP consumer.
   * tap4j (http://www.tap4j.org/), a Java-based project implementing
     both a TAP producer and a TAP consumer.

15.5 DejaGnu Tests
==================

If 'dejagnu' (ftp://ftp.gnu.org/gnu/dejagnu/) appears in
'AUTOMAKE_OPTIONS', then a 'dejagnu'-based test suite is assumed.  The
variable 'DEJATOOL' is a list of names that are passed, one at a time,
as the '--tool' argument to 'runtest' invocations; it defaults to the
name of the package.

   The variable 'RUNTESTDEFAULTFLAGS' holds the '--tool' and '--srcdir'
flags that are passed to dejagnu by default; this can be overridden if
necessary.

   The variables 'EXPECT' and 'RUNTEST' can also be overridden to
provide project-specific values.  For instance, you will need to do this
if you are testing a compiler toolchain, because the default values do
not take into account host and target names.

   The contents of the variable 'RUNTESTFLAGS' are passed to the
'runtest' invocation.  This is considered a "user variable" (*note User
Variables::).  If you need to set 'runtest' flags in 'Makefile.am', you
can use 'AM_RUNTESTFLAGS' instead.

   Automake will generate rules to create a local 'site.exp' file,
defining various variables detected by 'configure'.  This file is
automatically read by DejaGnu.  It is OK for the user of a package to
edit this file in order to tune the test suite.  However this is not the
place where the test suite author should define new variables: this
should be done elsewhere in the real test suite code.  Especially,
'site.exp' should not be distributed.

   Still, if the package author has legitimate reasons to extend
'site.exp' at 'make' time, he can do so by defining the variable
'EXTRA_DEJAGNU_SITE_CONFIG'; the files listed there will be considered
'site.exp' prerequisites, and their content will be appended to it (in
the same order in which they appear in 'EXTRA_DEJAGNU_SITE_CONFIG').
Note that files are _not_ distributed by default.

   For more information regarding DejaGnu test suites, see *note
(dejagnu)Top::.

15.6 Install Tests
==================

The 'installcheck' target is available to the user as a way to run any
tests after the package has been installed.  You can add tests to this
by writing an 'installcheck-local' rule.

16 Rebuilding Makefiles
***********************

Automake generates rules to automatically rebuild 'Makefile's,
'configure', and other derived files like 'Makefile.in'.

   If you are using 'AM_MAINTAINER_MODE' in 'configure.ac', then these
automatic rebuilding rules are only enabled in maintainer mode.

   Sometimes it is convenient to supplement the rebuild rules for
'configure' or 'config.status' with additional dependencies.  The
variables 'CONFIGURE_DEPENDENCIES' and 'CONFIG_STATUS_DEPENDENCIES' can
be used to list these extra dependencies.  These variables should be
defined in all 'Makefile's of the tree (because these two rebuild rules
are output in all them), so it is safer and easier to 'AC_SUBST' them
from 'configure.ac'.  For instance, the following statement will cause
'configure' to be rerun each time 'version.sh' is changed.

     AC_SUBST([CONFIG_STATUS_DEPENDENCIES], ['$(top_srcdir)/version.sh'])

Note the '$(top_srcdir)/' in the file name.  Since this variable is to
be used in all 'Makefile's, its value must be sensible at any level in
the build hierarchy.

   Beware not to mistake 'CONFIGURE_DEPENDENCIES' for
'CONFIG_STATUS_DEPENDENCIES'.

   'CONFIGURE_DEPENDENCIES' adds dependencies to the 'configure' rule,
whose effect is to run 'autoconf'.  This variable should be seldom used,
because 'automake' already tracks 'm4_include'd files.  However it can
be useful when playing tricky games with 'm4_esyscmd' or similar
non-recommendable macros with side effects.  Be also aware that
interactions of this variable with the *note autom4te cache:
(autoconf)Autom4te Cache. are quite problematic and can cause subtle
breakage, so you might want to disable the cache if you want to use
'CONFIGURE_DEPENDENCIES'.

   'CONFIG_STATUS_DEPENDENCIES' adds dependencies to the 'config.status'
rule, whose effect is to run 'configure'.  This variable should
therefore carry any non-standard source that may be read as a side
effect of running 'configure', like 'version.sh' in the example above.

   Speaking of 'version.sh' scripts, we recommend against them today.
They are mainly used when the version of a package is updated
automatically by a script (e.g., in daily builds).  Here is what some
old-style 'configure.ac's may look like:

     AC_INIT
     . $srcdir/version.sh
     AM_INIT_AUTOMAKE([name], $VERSION_NUMBER)
     ...

Here, 'version.sh' is a shell fragment that sets 'VERSION_NUMBER'.  The
problem with this example is that 'automake' cannot track dependencies
(listing 'version.sh' in 'CONFIG_STATUS_DEPENDENCIES', and distributing
this file is up to the user), and that it uses the obsolete form of
'AC_INIT' and 'AM_INIT_AUTOMAKE'.  Upgrading to the new syntax is not
straightforward, because shell variables are not allowed in 'AC_INIT''s
arguments.  We recommend that 'version.sh' be replaced by an M4 file
that is included by 'configure.ac':

     m4_include([version.m4])
     AC_INIT([name], VERSION_NUMBER)
     AM_INIT_AUTOMAKE
     ...

Here 'version.m4' could contain something like
'm4_define([VERSION_NUMBER], [1.2])'.  The advantage of this second form
is that 'automake' will take care of the dependencies when defining the
rebuild rule, and will also distribute the file automatically.  An
inconvenience is that 'autoconf' will now be rerun each time the version
number is bumped, when only 'configure' had to be rerun in the previous
setup.

17 Changing Automake's Behavior
*******************************

17.1 Options generalities
=========================

Various features of Automake can be controlled by options.  Except where
noted otherwise, options can be specified in one of several ways.  Most
options can be applied on a per-'Makefile' basis when listed in a
special 'Makefile' variable named 'AUTOMAKE_OPTIONS'.  Some of these
options only make sense when specified in the toplevel 'Makefile.am'
file.  Options are applied globally to all processed 'Makefile' files
when listed in the first argument of 'AM_INIT_AUTOMAKE' in
'configure.ac', and some options which require changes to the
'configure' script can only be specified there.  These are annotated
below.

   As a general rule, options specified in 'AUTOMAKE_OPTIONS' take
precedence over those specified in 'AM_INIT_AUTOMAKE', which in turn
take precedence over those specified on the command line.

   Also, some care must be taken about the interactions among strictness
level and warning categories.  As a general rule, strictness-implied
warnings are overridden by those specified by explicit options.  For
example, even if 'portability' warnings are disabled by default in
'foreign' strictness, an usage like this will end up enabling them:

     AUTOMAKE_OPTIONS = -Wportability foreign

   However, a strictness level specified in a higher-priority context
will override all the explicit warnings specified in a lower-priority
context.  For example, if 'configure.ac' contains:

     AM_INIT_AUTOMAKE([-Wportability])

and 'Makefile.am' contains:

     AUTOMAKE_OPTIONS = foreign

then 'portability' warnings will be _disabled_ in 'Makefile.am'.

17.2 List of Automake options
=============================

'gnits'
'gnu'
'foreign'

     Set the strictness as appropriate.  The 'gnits' option also implies
     options 'readme-alpha' and 'check-news'.

'check-news'
     Cause 'make dist' to fail unless the current version number appears
     in the first few lines of the 'NEWS' file.

'dejagnu'
     Cause 'dejagnu'-specific rules to be generated.  *Note DejaGnu
     Tests::.

'dist-bzip2'
     Hook 'dist-bzip2' to 'dist'.

'dist-lzip'
     Hook 'dist-lzip' to 'dist'.

'dist-xz'
     Hook 'dist-xz' to 'dist'.

'dist-zip'
     Hook 'dist-zip' to 'dist'.

'dist-shar'
     Hook 'dist-shar' to 'dist'.  Use of this option is deprecated, as
     the 'shar' format is obsolescent and problematic.  Support for it
     will be removed altogether in Automake 2.0.

'dist-tarZ'
     Hook 'dist-tarZ' to 'dist'.  Use of this option is deprecated, as
     the 'compress' program is obsolete.  Support for it will be removed
     altogether in Automake 2.0.

'filename-length-max=99'
     Abort if file names longer than 99 characters are found during
     'make dist'.  Such long file names are generally considered not to
     be portable in tarballs.  See the 'tar-v7' and 'tar-ustar' options
     below.  This option should be used in the top-level 'Makefile.am'
     or as an argument of 'AM_INIT_AUTOMAKE' in 'configure.ac', it will
     be ignored otherwise.  It will also be ignored in sub-packages of
     nested packages (*note Subpackages::).

'info-in-builddir'
     Instruct Automake to place the generated '.info' files in the
     'builddir' rather than in the 'srcdir'.  Note that this might make
     VPATH builds with some non-GNU make implementations more brittle.

'no-define'
     This option is meaningful only when passed as an argument to
     'AM_INIT_AUTOMAKE'.  It will prevent the 'PACKAGE' and 'VERSION'
     variables from being 'AC_DEFINE'd.

'no-dependencies'
     This is similar to using '--ignore-deps' on the command line, but
     is useful for those situations where you don't have the necessary
     bits to make automatic dependency tracking work (*note
     Dependencies::).  In this case the effect is to effectively disable
     automatic dependency tracking.

'no-dist'
     Don't emit any code related to 'dist' target.  This is useful when
     a package has its own method for making distributions.

'no-dist-gzip'
     Do not hook 'dist-gzip' to 'dist'.

'no-exeext'
     If your 'Makefile.am' defines a rule for target 'foo', it will
     override a rule for a target named 'foo$(EXEEXT)'.  This is
     necessary when 'EXEEXT' is found to be empty.  However, by default
     'automake' will generate an error for this use.  The 'no-exeext'
     option will disable this error.  This is intended for use only
     where it is known in advance that the package will not be ported to
     Windows, or any other operating system using extensions on
     executables.

'no-installinfo'
     The generated 'Makefile.in' will not cause info pages to be built
     or installed by default.  However, 'info' and 'install-info'
     targets will still be available.  This option is disallowed at
     'gnu' strictness and above.

'no-installman'
     The generated 'Makefile.in' will not cause man pages to be
     installed by default.  However, an 'install-man' target will still
     be available for optional installation.  This option is disallowed
     at 'gnu' strictness and above.

'nostdinc'
     This option can be used to disable the standard '-I' options that
     are ordinarily automatically provided by Automake.

'no-texinfo.tex'
     Don't require 'texinfo.tex', even if there are texinfo files in
     this directory.

'serial-tests'
     Enable the older serial test suite harness for 'TESTS' (*note
     Serial Test Harness::, for more information).

'parallel-tests'
     Enable test suite harness for 'TESTS' that can run tests in
     parallel (*note Parallel Test Harness::, for more information).
     This option is only kept for backward-compatibility, since the
     parallel test harness is the default now.

'readme-alpha'
     If this release is an alpha release, and the file 'README-alpha'
     exists, then it will be added to the distribution.  If this option
     is given, version numbers are expected to follow one of two forms.
     The first form is 'MAJOR.MINOR.ALPHA', where each element is a
     number; the final period and number should be left off for
     non-alpha releases.  The second form is 'MAJOR.MINORALPHA', where
     ALPHA is a letter; it should be omitted for non-alpha releases.

'std-options'

     Make the 'installcheck' rule check that installed scripts and
     programs support the '--help' and '--version' options.  This also
     provides a basic check that the program's run-time dependencies are
     satisfied after installation.

     In a few situations, programs (or scripts) have to be exempted from
     this test.  For instance, 'false' (from GNU coreutils) is never
     successful, even for '--help' or '--version'.  You can list such
     programs in the variable 'AM_INSTALLCHECK_STD_OPTIONS_EXEMPT'.
     Programs (not scripts) listed in this variable should be suffixed
     by '$(EXEEXT)' for the sake of Windows or OS/2.  For instance,
     suppose we build 'false' as a program but 'true.sh' as a script,
     and that neither of them support '--help' or '--version':

          AUTOMAKE_OPTIONS = std-options
          bin_PROGRAMS = false ...
          bin_SCRIPTS = true.sh ...
          AM_INSTALLCHECK_STD_OPTIONS_EXEMPT = false$(EXEEXT) true.sh

'subdir-objects'
     If this option is specified, then objects are placed into the
     subdirectory of the build directory corresponding to the
     subdirectory of the source file.  For instance, if the source file
     is 'subdir/file.cxx', then the output file would be
     'subdir/file.o'.

'tar-v7'
'tar-ustar'
'tar-pax'

     These three mutually exclusive options select the tar format to use
     when generating tarballs with 'make dist'.  (The tar file created
     is then compressed according to the set of 'no-dist-gzip',
     'dist-bzip2', 'dist-lzip', 'dist-xz' and 'dist-tarZ' options in
     use.)

     These options must be passed as arguments to 'AM_INIT_AUTOMAKE'
     (*note Macros::) because they can require additional configure
     checks.  Automake will complain if it sees such options in an
     'AUTOMAKE_OPTIONS' variable.

     'tar-v7' selects the old V7 tar format.  This is the historical
     default.  This antiquated format is understood by all tar
     implementations and supports file names with up to 99 characters.
     When given longer file names some tar implementations will diagnose
     the problem while other will generate broken tarballs or use
     non-portable extensions.  Furthermore, the V7 format cannot store
     empty directories.  When using this format, consider using the
     'filename-length-max=99' option to catch file names too long.

     'tar-ustar' selects the ustar format defined by POSIX 1003.1-1988.
     This format is believed to be old enough to be portable.  It fully
     supports empty directories.  It can store file names with up to 256
     characters, provided that the file name can be split at directory
     separator in two parts, first of them being at most 155 bytes long.
     So, in most cases the maximum file name length will be shorter than
     256 characters.  However you may run against broken tar
     implementations that incorrectly handle file names longer than 99
     characters (please report them to <bug-automake@gnu.org> so we can
     document this accurately).

     'tar-pax' selects the new pax interchange format defined by POSIX
     1003.1-2001.  It does not limit the length of file names.  However,
     this format is very young and should probably be restricted to
     packages that target only very modern platforms.  There are moves
     to change the pax format in an upward-compatible way, so this
     option may refer to a more recent version in the future.

     *Note Controlling the Archive Format: (tar)Formats, for further
     discussion about tar formats.

     'configure' knows several ways to construct these formats.  It will
     not abort if it cannot find a tool up to the task (so that the
     package can still be built), but 'make dist' will fail.

VERSION
     A version number (e.g., '0.30') can be specified.  If Automake is
     not newer than the version specified, creation of the 'Makefile.in'
     will be suppressed.

'-WCATEGORY' or '--warnings=CATEGORY'
     These options behave exactly like their command-line counterpart
     (*note automake Invocation::).  This allows you to enable or
     disable some warning categories on a per-file basis.  You can also
     setup some warnings for your entire project; for instance, try
     'AM_INIT_AUTOMAKE([-Wall])' in your 'configure.ac'.

   Unrecognized options are diagnosed by 'automake'.

   If you want an option to apply to all the files in the tree, you can
use the 'AM_INIT_AUTOMAKE' macro in 'configure.ac'.  *Note Macros::.

18 Miscellaneous Rules
**********************

There are a few rules and variables that didn't fit anywhere else.

18.1 Interfacing to 'etags'
===========================

Automake will generate rules to generate 'TAGS' files for use with GNU
Emacs under some circumstances.

   If any C, C++ or Fortran 77 source code or headers are present, then
'tags' and 'TAGS' rules will be generated for the directory.  All files
listed using the '_SOURCES', '_HEADERS', and '_LISP' primaries will be
used to generate tags.  Note that generated source files that are not
distributed must be declared in variables like 'nodist_noinst_HEADERS'
or 'nodist_PROG_SOURCES' or they will be ignored.

   A 'tags' rule will be output at the topmost directory of a
multi-directory package.  When run from this topmost directory, 'make
tags' will generate a 'TAGS' file that includes by reference all 'TAGS'
files from subdirectories.

   The 'tags' rule will also be generated if the variable 'ETAGS_ARGS'
is defined.  This variable is intended for use in directories that
contain taggable source that 'etags' does not understand.  The user can
use the 'ETAGSFLAGS' to pass additional flags to 'etags';
'AM_ETAGSFLAGS' is also available for use in 'Makefile.am'.

   Here is how Automake generates tags for its source, and for nodes in
its Texinfo file:

     ETAGS_ARGS = automake.in --lang=none 
      --regex='/^@node[ t]+([^,]+)/1/' automake.texi

   If you add file names to 'ETAGS_ARGS', you will probably also want to
define 'TAGS_DEPENDENCIES'.  The contents of this variable are added
directly to the dependencies for the 'tags' rule.

   Automake also generates a 'ctags' rule that can be used to build
'vi'-style 'tags' files.  The variable 'CTAGS' is the name of the
program to invoke (by default 'ctags'); 'CTAGSFLAGS' can be used by the
user to pass additional flags, and 'AM_CTAGSFLAGS' can be used by the
'Makefile.am'.

   Automake will also generate an 'ID' rule that will run 'mkid' on the
source.  This is only supported on a directory-by-directory basis.

   Similarly, the 'cscope' rule will create a list of all the source
files in the tree and run 'cscope' to build an inverted index database.
The variable 'CSCOPE' is the name of the program to invoke (by default
'cscope'); 'CSCOPEFLAGS' and 'CSCOPE_ARGS' can be used by the user to
pass additional flags and file names respectively, while
'AM_CSCOPEFLAGS' can be used by the 'Makefile.am'.  Note that,
currently, the Automake-provided 'cscope' support, when used in a VPATH
build, might not work well with non-GNU make implementations (especially
with make implementations performing *note VPATH rewrites:
(autoconf)Automatic Rule Rewriting.).

   Finally, Automake also emits rules to support the GNU Global Tags
program (http://www.gnu.org/software/global/).  The 'GTAGS' rule runs
Global Tags and puts the result in the top build directory.  The
variable 'GTAGS_ARGS' holds arguments that are passed to 'gtags'.

18.2 Handling new file extensions
=================================

It is sometimes useful to introduce a new implicit rule to handle a file
type that Automake does not know about.

   For instance, suppose you had a compiler that could compile '.foo'
files to '.o' files.  You would simply define a suffix rule for your
language:

     .foo.o:
             foocc -c -o $@ $<

   Then you could directly use a '.foo' file in a '_SOURCES' variable
and expect the correct results:

     bin_PROGRAMS = doit
     doit_SOURCES = doit.foo

   This was the simpler and more common case.  In other cases, you will
have to help Automake to figure out which extensions you are defining
your suffix rule for.  This usually happens when your extension does not
start with a dot.  Then, all you have to do is to put a list of new
suffixes in the 'SUFFIXES' variable *before* you define your implicit
rule.

   For instance, the following definition prevents Automake from
misinterpreting the '.idlC.cpp:' rule as an attempt to transform '.idlC'
files into '.cpp' files.

     SUFFIXES = .idl C.cpp
     .idlC.cpp:
             # whatever

   As you may have noted, the 'SUFFIXES' variable behaves like the
'.SUFFIXES' special target of 'make'.  You should not touch '.SUFFIXES'
yourself, but use 'SUFFIXES' instead and let Automake generate the
suffix list for '.SUFFIXES'.  Any given 'SUFFIXES' go at the start of
the generated suffixes list, followed by Automake generated suffixes not
already in the list.

19 Include
**********

Automake supports an 'include' directive that can be used to include
other 'Makefile' fragments when 'automake' is run.  Note that these
fragments are read and interpreted by 'automake', not by 'make'.  As
with conditionals, 'make' has no idea that 'include' is in use.

   There are two forms of 'include':

'include $(srcdir)/file'
     Include a fragment that is found relative to the current source
     directory.

'include $(top_srcdir)/file'
     Include a fragment that is found relative to the top source
     directory.

   Note that if a fragment is included inside a conditional, then the
condition applies to the entire contents of that fragment.

   Makefile fragments included this way are always distributed because
they are needed to rebuild 'Makefile.in'.

   Inside a fragment, the construct '%reldir%' is replaced with the
directory of the fragment relative to the base 'Makefile.am'.
Similarly, '%canon_reldir%' is replaced with the canonicalized (*note
Canonicalization::) form of '%reldir%'.  As a convenience, '%D%' is a
synonym for '%reldir%', and '%C%' is a synonym for '%canon_reldir%'.

   A special feature is that if the fragment is in the same directory as
the base 'Makefile.am' (i.e., '%reldir%' is '.'), then '%reldir%' and
'%canon_reldir%' will expand to the empty string as well as eat, if
present, a following slash or underscore respectively.

   Thus, a makefile fragment might look like this:

     bin_PROGRAMS += %reldir%/mumble
     %canon_reldir%_mumble_SOURCES = %reldir%/one.c

20 Conditionals
***************

Automake supports a simple type of conditionals.

   These conditionals are not the same as conditionals in GNU Make.
Automake conditionals are checked at configure time by the 'configure'
script, and affect the translation from 'Makefile.in' to 'Makefile'.
They are based on options passed to 'configure' and on results that
'configure' has discovered about the host system.  GNU Make conditionals
are checked at 'make' time, and are based on variables passed to the
make program or defined in the 'Makefile'.

   Automake conditionals will work with any make program.

20.1 Usage of Conditionals
==========================

Before using a conditional, you must define it by using 'AM_CONDITIONAL'
in the 'configure.ac' file (*note Macros::).

 -- Macro: AM_CONDITIONAL (CONDITIONAL, CONDITION)
     The conditional name, CONDITIONAL, should be a simple string
     starting with a letter and containing only letters, digits, and
     underscores.  It must be different from 'TRUE' and 'FALSE' that are
     reserved by Automake.

     The shell CONDITION (suitable for use in a shell 'if' statement) is
     evaluated when 'configure' is run.  Note that you must arrange for
     _every_ 'AM_CONDITIONAL' to be invoked every time 'configure' is
     run.  If 'AM_CONDITIONAL' is run conditionally (e.g., in a shell
     'if' statement), then the result will confuse 'automake'.

   Conditionals typically depend upon options that the user provides to
the 'configure' script.  Here is an example of how to write a
conditional that is true if the user uses the '--enable-debug' option.

     AC_ARG_ENABLE([debug],
     [  --enable-debug    Turn on debugging],
     [case "${enableval}" in
       yes) debug=true ;;
       no)  debug=false ;;
       *) AC_MSG_ERROR([bad value ${enableval} for --enable-debug]) ;;
     esac],[debug=false])
     AM_CONDITIONAL([DEBUG], [test x$debug = xtrue])

   Here is an example of how to use that conditional in 'Makefile.am':

     if DEBUG
     DBG = debug
     else
     DBG =
     endif
     noinst_PROGRAMS = $(DBG)

   This trivial example could also be handled using 'EXTRA_PROGRAMS'
(*note Conditional Programs::).

   You may only test a single variable in an 'if' statement, possibly
negated using '!'.  The 'else' statement may be omitted.  Conditionals
may be nested to any depth.  You may specify an argument to 'else' in
which case it must be the negation of the condition used for the current
'if'.  Similarly you may specify the condition that is closed on the
'endif' line:

     if DEBUG
     DBG = debug
     else !DEBUG
     DBG =
     endif !DEBUG

Unbalanced conditions are errors.  The 'if', 'else', and 'endif'
statements should not be indented, i.e., start on column one.

   The 'else' branch of the above two examples could be omitted, since
assigning the empty string to an otherwise undefined variable makes no
difference.

   In order to allow access to the condition registered by
'AM_CONDITIONAL' inside 'configure.ac', and to allow conditional
'AC_CONFIG_FILES', 'AM_COND_IF' may be used:

 -- Macro: AM_COND_IF (CONDITIONAL, [IF-TRUE], [IF-FALSE])
     If CONDITIONAL is fulfilled, execute IF-TRUE, otherwise execute
     IF-FALSE.  If either branch contains 'AC_CONFIG_FILES', it will
     cause 'automake' to output the rules for the respective files only
     for the given condition.

   'AM_COND_IF' macros may be nested when m4 quotation is used properly
(*note (autoconf)M4 Quotation::).

   Here is an example of how to define a conditional config file:

     AM_CONDITIONAL([SHELL_WRAPPER], [test "x$with_wrapper" = xtrue])
     AM_COND_IF([SHELL_WRAPPER],
                [AC_CONFIG_FILES([wrapper:wrapper.in])])

20.2 Limits of Conditionals
===========================

Conditionals should enclose complete statements like variables or rules
definitions.  Automake cannot deal with conditionals used inside a
variable definition, for instance, and is not even able to diagnose this
situation.  The following example would not work:

     # This syntax is not understood by Automake
     AM_CPPFLAGS = 
       -DFEATURE_A 
     if WANT_DEBUG
       -DDEBUG 
     endif
       -DFEATURE_B

   However the intended definition of 'AM_CPPFLAGS' can be achieved with

     if WANT_DEBUG
       DEBUGFLAGS = -DDEBUG
     endif
     AM_CPPFLAGS = -DFEATURE_A $(DEBUGFLAGS) -DFEATURE_B

or

     AM_CPPFLAGS = -DFEATURE_A
     if WANT_DEBUG
     AM_CPPFLAGS += -DDEBUG
     endif
     AM_CPPFLAGS += -DFEATURE_B

   More details and examples of conditionals are described alongside
various Automake features in this manual (*note Conditional
Subdirectories::, *note Conditional Sources::, *note Conditional
Programs::, *note Conditional Libtool Libraries::, *note Conditional
Libtool Sources::).

21 Silencing 'make'
*******************

21.1 Make is verbose by default
===============================

Normally, when executing the set of rules associated with a target,
'make' prints each rule before it is executed.  This behaviour, while
having been in place for a long time, and being even mandated by the
POSIX standard, starkly violates the "silence is golden" UNIX
principle(1):

     When a program has nothing interesting or surprising to say, it
     should say nothing.  Well-behaved Unix programs do their jobs
     unobtrusively, with a minimum of fuss and bother.  Silence is
     golden.

   In fact, while such verbosity of 'make' can theoretically be useful
to track bugs and understand reasons of failures right away, it can also
hide warning and error messages from 'make'-invoked tools, drowning them
in a flood of uninteresting and seldom useful messages, and thus
allowing them to go easily undetected.

   This problem can be very annoying, especially for developers, who
usually know quite well what's going on behind the scenes, and for whom
the verbose output from 'make' ends up being mostly noise that hampers
the easy detection of potentially important warning messages.

   ---------- Footnotes ----------

   (1) See also <http://catb.org/~esr/writings/taoup/html/ch11s09.html>.

21.2 Standard and generic ways to silence make
==============================================

Here we describe some common idioms/tricks to obtain a quieter make
output, with their relative advantages and drawbacks.  In the next
section (*note Automake Silent Rules::) we'll see how Automake can help
in this respect, providing more elaborate and flexible idioms.

   * 'make -s'

     This simply causes 'make' not to print _any_ rule before executing
     it.

     The '-s' flag is mandated by POSIX, universally supported, and its
     purpose and function are easy to understand.

     But it also has its serious limitations too.  First of all, it
     embodies an "all or nothing" strategy, i.e., either everything is
     silenced, or nothing is; this lack of granularity can sometimes be
     a fatal flaw.  Moreover, when the '-s' flag is used, the 'make'
     output might turn out to be too much terse; in case of errors, the
     user won't be able to easily see what rule or command have caused
     them, or even, in case of tools with poor error reporting, what the
     errors were!

   * 'make >/dev/null || make'

     Apparently, this perfectly obeys the "silence is golden" rule:
     warnings from stderr are passed through, output reporting is done
     only in case of error, and in that case it should provide a
     verbose-enough report to allow an easy determination of the error
     location and causes.

     However, calling 'make' two times in a row might hide errors
     (especially intermittent ones), or subtly change the expected
     semantic of the 'make' calls -- things these which can clearly make
     debugging and error assessment very difficult.

   * 'make --no-print-directory'

     This is GNU 'make' specific.  When called with the
     '--no-print-directory' option, GNU 'make' will disable printing of
     the working directory by invoked sub-'make's (the well-known
     "Entering/Leaving directory ..."  messages).  This helps to
     decrease the verbosity of the output, but experience has shown that
     it can also often render debugging considerably harder in projects
     using deeply-nested 'make' recursion.

     As an aside, notice that the '--no-print-directory' option is
     automatically activated if the '-s' flag is used.

21.3 How Automake can help in silencing make
============================================

The tricks and idioms for silencing 'make' described in the previous
section can be useful from time to time, but we've seen that they all
have their serious drawbacks and limitations.  That's why automake
provides support for a more advanced and flexible way of obtaining
quieter output from 'make' (for most rules at least).

   To give the gist of what Automake can do in this respect, here is a
simple comparison between a typical 'make' output (where silent rules
are disabled) and one with silent rules enabled:

     % cat Makefile.am
     bin_PROGRAMS = foo
     foo_SOURCES = main.c func.c
     % cat main.c
     int main (void) { return func (); }  /* func used undeclared */
     % cat func.c
     int func (void) { int i; return i; } /* i used uninitialized */

     The make output is by default very verbose.  This causes warnings
     from the compiler to be somewhat hidden, and not immediate to spot.
     % make CFLAGS=-Wall
     gcc -DPACKAGE_NAME="foo" -DPACKAGE_TARNAME="foo" ...
     -DPACKAGE_STRING="foo 1.0" -DPACKAGE_BUGREPORT="" ...
     -DPACKAGE="foo" -DVERSION="1.0" -I. -Wall -MT main.o
     -MD -MP -MF .deps/main.Tpo -c -o main.o main.c
     main.c: In function 鈥榤ain鈥�:
     main.c:3:3: warning: implicit declaration of function 鈥榝unc鈥�
     mv -f .deps/main.Tpo .deps/main.Po
     gcc -DPACKAGE_NAME="foo" -DPACKAGE_TARNAME="foo" ...
     -DPACKAGE_STRING="foo 1.0" -DPACKAGE_BUGREPORT="" ...
     -DPACKAGE="foo" -DVERSION="1.0" -I. -Wall -MT func.o
     -MD -MP -MF .deps/func.Tpo -c -o func.o func.c
     func.c: In function 鈥榝unc鈥�:
     func.c:4:3: warning: 鈥榠鈥� used uninitialized in this function
     mv -f .deps/func.Tpo .deps/func.Po
     gcc -Wall -o foo main.o func.o

     Clean up, so that we we can rebuild everything from scratch.
     % make clean
     test -z "foo" || rm -f foo
     rm -f *.o

     Silent rules enabled: the output is minimal but informative.  In
     particular, the warnings from the compiler stick out very clearly.
     % make V=0 CFLAGS=-Wall
       CC     main.o
     main.c: In function 鈥榤ain鈥�:
     main.c:3:3: warning: implicit declaration of function 鈥榝unc鈥�
       CC     func.o
     func.c: In function 鈥榝unc鈥�:
     func.c:4:3: warning: 鈥榠鈥� used uninitialized in this function
       CCLD   foo

   Also, in projects using 'libtool', the use of silent rules can
automatically enable the 'libtool''s '--silent' option:

     % cat Makefile.am
     lib_LTLIBRARIES = libx.la

     % make # Both make and libtool are verbose by default.
     ...
     libtool: compile: gcc -DPACKAGE_NAME="foo" ... -DLT_OBJDIR=".libs/"
       -I. -g -O2 -MT libx.lo -MD -MP -MF .deps/libx.Tpo -c libx.c -fPIC
       -DPIC -o .libs/libx.o
     mv -f .deps/libx.Tpo .deps/libx.Plo
     /bin/sh ./libtool --tag=CC --mode=link gcc -g -O2 -o libx.la -rpath
       /usr/local/lib libx.lo
     libtool: link: gcc -shared .libs/libx.o -Wl,-soname -Wl,libx.so.0
       -o .libs/libx.so.0.0.0
     libtool: link: cd .libs && rm -f libx.so && ln -s libx.so.0.0.0 libx.so
     ...

     % make V=0
       CC     libx.lo
       CCLD   libx.la

   For Automake-generated 'Makefile's, the user may influence the
verbosity at 'configure' run time as well as at 'make' run time:

   * Passing '--enable-silent-rules' to 'configure' will cause build
     rules to be less verbose; the option '--disable-silent-rules' will
     cause normal verbose output.
   * At 'make' run time, the default chosen at 'configure' time may be
     overridden: 'make V=1' will produce verbose output, 'make V=0' less
     verbose output.

   Note that silent rules are _disabled_ by default; the user must
enable them explicitly at either 'configure' run time or at 'make' run
time.  We think that this is a good policy, since it provides the casual
user with enough information to prepare a good bug report in case
anything breaks.

   Still, notwithstanding the rationales above, a developer who really
wants to make silent rules enabled by default in his own package can do
so by calling 'AM_SILENT_RULES([yes])' in 'configure.ac'.

   Users who prefer to have silent rules enabled by default can edit
their 'config.site' file to make the variable 'enable_silent_rules'
default to 'yes'.  This should still allow disabling silent rules at
'configure' time and at 'make' time.

   For portability to different 'make' implementations, package authors
are advised to not set the variable 'V' inside the 'Makefile.am' file,
to allow the user to override the value for subdirectories as well.

   To work at its best, the current implementation of this feature
normally uses nested variable expansion '$(VAR1$(V))', a 'Makefile'
feature that is not required by POSIX 2008 but is widely supported in
practice.  On the rare 'make' implementations that do not support nested
variable expansion, whether rules are silent is always determined at
configure time, and cannot be overridden at make time.  Future versions
of POSIX are likely to require nested variable expansion, so this minor
limitation should go away with time.

   To extend the silent mode to your own rules, you have few choices:

   * You can use the predefined variable 'AM_V_GEN' as a prefix to
     commands that should output a status line in silent mode, and
     'AM_V_at' as a prefix to commands that should not output anything
     in silent mode.  When output is to be verbose, both of these
     variables will expand to the empty string.

   * You can silence a recipe unconditionally with '@', and then use the
     predefined variable 'AM_V_P' to know whether make is being run in
     silent or verbose mode, adjust the verbose information your recipe
     displays accordingly:

          generate-headers:
                          ... [commands defining a shell variable '$headers'] ...; 
                  if $(AM_V_P); then set -x; else echo " GEN   [headers]"; fi; 
                  rm -f $$headers && generate-header --flags $$headers

   * You can add your own variables, so strings of your own choice are
     shown.  The following snippet shows how you would define your own
     equivalent of 'AM_V_GEN':

          pkg_verbose = $(pkg_verbose_@AM_V@)
          pkg_verbose_ = $(pkg_verbose_@AM_DEFAULT_V@)
          pkg_verbose_0 = @echo PKG-GEN $@;

          foo: foo.in
                  $(pkg_verbose)cp $(srcdir)/foo.in $@

   As a final note, observe that, even when silent rules are enabled,
the '--no-print-directory' option is still required with GNU 'make' if
the "Entering/Leaving directory ..."  messages are to be disabled.

22 The effect of '--gnu' and '--gnits'
**************************************

The '--gnu' option (or 'gnu' in the 'AUTOMAKE_OPTIONS' variable) causes
'automake' to check the following:

   * The files 'INSTALL', 'NEWS', 'README', 'AUTHORS', and 'ChangeLog',
     plus one of 'COPYING.LIB', 'COPYING.LESSER' or 'COPYING', are
     required at the topmost directory of the package.

     If the '--add-missing' option is given, 'automake' will add a
     generic version of the 'INSTALL' file as well as the 'COPYING' file
     containing the text of the current version of the GNU General
     Public License existing at the time of this Automake release
     (version 3 as this is written,
     <http://www.gnu.org/copyleft/gpl.html>).  However, an existing
     'COPYING' file will never be overwritten by 'automake'.

   * The options 'no-installman' and 'no-installinfo' are prohibited.

   Note that this option will be extended in the future to do even more
checking; it is advisable to be familiar with the precise requirements
of the GNU standards.  Also, '--gnu' can require certain non-standard
GNU programs to exist for use by various maintainer-only rules; for
instance, in the future 'pathchk' might be required for 'make dist'.

   The '--gnits' option does everything that '--gnu' does, and checks
the following as well:

   * 'make installcheck' will check to make sure that the '--help' and
     '--version' really print a usage message and a version string,
     respectively.  This is the 'std-options' option (*note Options::).

   * 'make dist' will check to make sure the 'NEWS' file has been
     updated to the current version.

   * 'VERSION' is checked to make sure its format complies with Gnits
     standards.

   * If 'VERSION' indicates that this is an alpha release, and the file
     'README-alpha' appears in the topmost directory of a package, then
     it is included in the distribution.  This is done in '--gnits'
     mode, and no other, because this mode is the only one where version
     number formats are constrained, and hence the only mode where
     Automake can automatically determine whether 'README-alpha' should
     be included.

   * The file 'THANKS' is required.

23 When Automake Isn't Enough
*****************************

In some situations, where Automake is not up to one task, one has to
resort to handwritten rules or even handwritten 'Makefile's.

23.1 Extending Automake Rules
=============================

With some minor exceptions (for example '_PROGRAMS' variables, 'TESTS',
or 'XFAIL_TESTS') being rewritten to append '$(EXEEXT)'), the contents
of a 'Makefile.am' is copied to 'Makefile.in' verbatim.

   These copying semantics mean that many problems can be worked around
by simply adding some 'make' variables and rules to 'Makefile.am'.
Automake will ignore these additions.

   Since a 'Makefile.in' is built from data gathered from three
different places ('Makefile.am', 'configure.ac', and 'automake' itself),
it is possible to have conflicting definitions of rules or variables.
When building 'Makefile.in' the following priorities are respected by
'automake' to ensure the user always has the last word:

   * User defined variables in 'Makefile.am' have priority over
     variables 'AC_SUBST'ed from 'configure.ac', and 'AC_SUBST'ed
     variables have priority over 'automake'-defined variables.
   * As far as rules are concerned, a user-defined rule overrides any
     'automake'-defined rule for the same target.

   These overriding semantics make it possible to fine tune some default
settings of Automake, or replace some of its rules.  Overriding Automake
rules is often inadvisable, particularly in the topmost directory of a
package with subdirectories.  The '-Woverride' option (*note automake
Invocation::) comes in handy to catch overridden definitions.

   Note that Automake does not make any distinction between rules with
commands and rules that only specify dependencies.  So it is not
possible to append new dependencies to an 'automake'-defined target
without redefining the entire rule.

   However, various useful targets have a '-local' version you can
specify in your 'Makefile.am'.  Automake will supplement the standard
target with these user-supplied targets.

   The targets that support a local version are 'all', 'info', 'dvi',
'ps', 'pdf', 'html', 'check', 'install-data', 'install-dvi',
'install-exec', 'install-html', 'install-info', 'install-pdf',
'install-ps', 'uninstall', 'installdirs', 'installcheck' and the various
'clean' targets ('mostlyclean', 'clean', 'distclean', and
'maintainer-clean').

   Note that there are no 'uninstall-exec-local' or
'uninstall-data-local' targets; just use 'uninstall-local'.  It doesn't
make sense to uninstall just data or just executables.

   For instance, here is one way to erase a subdirectory during 'make
clean' (*note Clean::).

     clean-local:
             -rm -rf testSubDir

   You may be tempted to use 'install-data-local' to install a file to
some hard-coded location, but you should avoid this (*note Hard-Coded
Install Paths::).

   With the '-local' targets, there is no particular guarantee of
execution order; typically, they are run early, but with parallel make,
there is no way to be sure of that.

   In contrast, some rules also have a way to run another rule, called a
"hook"; hooks are always executed after the main rule's work is done.
The hook is named after the principal target, with '-hook' appended.
The targets allowing hooks are 'install-data', 'install-exec',
'uninstall', 'dist', and 'distcheck'.

   For instance, here is how to create a hard link to an installed
program:

     install-exec-hook:
             ln $(DESTDIR)$(bindir)/program$(EXEEXT) 
                $(DESTDIR)$(bindir)/proglink$(EXEEXT)

   Although cheaper and more portable than symbolic links, hard links
will not work everywhere (for instance, OS/2 does not have 'ln').
Ideally you should fall back to 'cp -p' when 'ln' does not work.  An
easy way, if symbolic links are acceptable to you, is to add
'AC_PROG_LN_S' to 'configure.ac' (*note Particular Program Checks:
(autoconf)Particular Programs.) and use '$(LN_S)' in 'Makefile.am'.

   For instance, here is how you could install a versioned copy of a
program using '$(LN_S)':

     install-exec-hook:
             cd $(DESTDIR)$(bindir) && 
               mv -f prog$(EXEEXT) prog-$(VERSION)$(EXEEXT) && 
               $(LN_S) prog-$(VERSION)$(EXEEXT) prog$(EXEEXT)

   Note that we rename the program so that a new version will erase the
symbolic link, not the real binary.  Also we 'cd' into the destination
directory in order to create relative links.

   When writing 'install-exec-hook' or 'install-data-hook', please bear
in mind that the exec/data distinction is based on the installation
directory, not on the primary used (*note The Two Parts of Install::).
So a 'foo_SCRIPTS' will be installed by 'install-data', and a
'barexec_SCRIPTS' will be installed by 'install-exec'.  You should
define your hooks consequently.

23.2 Third-Party 'Makefile's
============================

In most projects all 'Makefile's are generated by Automake.  In some
cases, however, projects need to embed subdirectories with handwritten
'Makefile's.  For instance, one subdirectory could be a third-party
project with its own build system, not using Automake.

   It is possible to list arbitrary directories in 'SUBDIRS' or
'DIST_SUBDIRS' provided each of these directories has a 'Makefile' that
recognizes all the following recursive targets.

   When a user runs one of these targets, that target is run recursively
in all subdirectories.  This is why it is important that even
third-party 'Makefile's support them.

'all'
     Compile the entire package.  This is the default target in
     Automake-generated 'Makefile's, but it does not need to be the
     default in third-party 'Makefile's.

'distdir'
     Copy files to distribute into '$(distdir)', before a tarball is
     constructed.  Of course this target is not required if the
     'no-dist' option (*note Options::) is used.

     The variables '$(top_distdir)' and '$(distdir)' (*note The dist
     Hook::) will be passed from the outer package to the subpackage
     when the 'distdir' target is invoked.  These two variables have
     been adjusted for the directory that is being recursed into, so
     they are ready to use.

'install'
'install-data'
'install-exec'
'uninstall'
     Install or uninstall files (*note Install::).

'install-dvi'
'install-html'
'install-info'
'install-ps'
'install-pdf'
     Install only some specific documentation format (*note Texinfo::).

'installdirs'
     Create install directories, but do not install any files.

'check'
'installcheck'
     Check the package (*note Tests::).

'mostlyclean'
'clean'
'distclean'
'maintainer-clean'
     Cleaning rules (*note Clean::).

'dvi'
'pdf'
'ps'
'info'
'html'
     Build the documentation in various formats (*note Texinfo::).

'tags'
'ctags'
     Build 'TAGS' and 'CTAGS' (*note Tags::).

   If you have ever used Gettext in a project, this is a good example of
how third-party 'Makefile's can be used with Automake.  The 'Makefile's
'gettextize' puts in the 'po/' and 'intl/' directories are handwritten
'Makefile's that implement all of these targets.  That way they can be
added to 'SUBDIRS' in Automake packages.

   Directories that are only listed in 'DIST_SUBDIRS' but not in
'SUBDIRS' need only the 'distclean', 'maintainer-clean', and 'distdir'
rules (*note Conditional Subdirectories::).

   Usually, many of these rules are irrelevant to the third-party
subproject, but they are required for the whole package to work.  It's
OK to have a rule that does nothing, so if you are integrating a
third-party project with no documentation or tag support, you could
simply augment its 'Makefile' as follows:

     EMPTY_AUTOMAKE_TARGETS = dvi pdf ps info html tags ctags
     .PHONY: $(EMPTY_AUTOMAKE_TARGETS)
     $(EMPTY_AUTOMAKE_TARGETS):

   Another aspect of integrating third-party build systems is whether
they support VPATH builds (*note VPATH Builds::).  Obviously if the
subpackage does not support VPATH builds the whole package will not
support VPATH builds.  This in turns means that 'make distcheck' will
not work, because it relies on VPATH builds.  Some people can live
without this (actually, many Automake users have never heard of 'make
distcheck').  Other people may prefer to revamp the existing 'Makefile's
to support VPATH.  Doing so does not necessarily require Automake, only
Autoconf is needed (*note Build Directories: (autoconf)Build
Directories.).  The necessary substitutions: '@srcdir@', '@top_srcdir@',
and '@top_builddir@' are defined by 'configure' when it processes a
'Makefile' (*note Preset Output Variables: (autoconf)Preset Output
Variables.), they are not computed by the Makefile like the
aforementioned '$(distdir)' and '$(top_distdir)' variables.

   It is sometimes inconvenient to modify a third-party 'Makefile' to
introduce the above required targets.  For instance, one may want to
keep the third-party sources untouched to ease upgrades to new versions.

   Here are two other ideas.  If GNU make is assumed, one possibility is
to add to that subdirectory a 'GNUmakefile' that defines the required
targets and includes the third-party 'Makefile'.  For this to work in
VPATH builds, 'GNUmakefile' must lie in the build directory; the easiest
way to do this is to write a 'GNUmakefile.in' instead, and have it
processed with 'AC_CONFIG_FILES' from the outer package.  For example if
we assume 'Makefile' defines all targets except the documentation
targets, and that the 'check' target is actually called 'test', we could
write 'GNUmakefile' (or 'GNUmakefile.in') like this:

     # First, include the real Makefile
     include Makefile
     # Then, define the other targets needed by Automake Makefiles.
     .PHONY: dvi pdf ps info html check
     dvi pdf ps info html:
     check: test

   A similar idea that does not use 'include' is to write a proxy
'Makefile' that dispatches rules to the real 'Makefile', either with
'$(MAKE) -f Makefile.real $(AM_MAKEFLAGS) target' (if it's OK to rename
the original 'Makefile') or with 'cd subdir && $(MAKE) $(AM_MAKEFLAGS)
target' (if it's OK to store the subdirectory project one directory
deeper).  The good news is that this proxy 'Makefile' can be generated
with Automake.  All we need are '-local' targets (*note Extending::)
that perform the dispatch.  Of course the other Automake features are
available, so you could decide to let Automake perform distribution or
installation.  Here is a possible 'Makefile.am':

     all-local:
             cd subdir && $(MAKE) $(AM_MAKEFLAGS) all
     check-local:
             cd subdir && $(MAKE) $(AM_MAKEFLAGS) test
     clean-local:
             cd subdir && $(MAKE) $(AM_MAKEFLAGS) clean

     # Assuming the package knows how to install itself
     install-data-local:
             cd subdir && $(MAKE) $(AM_MAKEFLAGS) install-data
     install-exec-local:
             cd subdir && $(MAKE) $(AM_MAKEFLAGS) install-exec
     uninstall-local:
             cd subdir && $(MAKE) $(AM_MAKEFLAGS) uninstall

     # Distribute files from here.
     EXTRA_DIST = subdir/Makefile subdir/program.c ...

   Pushing this idea to the extreme, it is also possible to ignore the
subproject build system and build everything from this proxy
'Makefile.am'.  This might sound very sensible if you need VPATH builds
but the subproject does not support them.

24 Distributing 'Makefile.in's
******************************

Automake places no restrictions on the distribution of the resulting
'Makefile.in's.  We still encourage software authors to distribute their
work under terms like those of the GPL, but doing so is not required to
use Automake.

   Some of the files that can be automatically installed via the
'--add-missing' switch do fall under the GPL.  However, these also have
a special exception allowing you to distribute them with your package,
regardless of the licensing you choose.

25 Automake API Versioning
**************************

New Automake releases usually include bug fixes and new features.
Unfortunately they may also introduce new bugs and incompatibilities.
This makes four reasons why a package may require a particular Automake
version.

   Things get worse when maintaining a large tree of packages, each one
requiring a different version of Automake.  In the past, this meant that
any developer (and sometimes users) had to install several versions of
Automake in different places, and switch '$PATH' appropriately for each
package.

   Starting with version 1.6, Automake installs versioned binaries.
This means you can install several versions of Automake in the same
'$prefix', and can select an arbitrary Automake version by running
'automake-1.6' or 'automake-1.7' without juggling with '$PATH'.
Furthermore, 'Makefile''s generated by Automake 1.6 will use
'automake-1.6' explicitly in their rebuild rules.

   The number '1.6' in 'automake-1.6' is Automake's API version, not
Automake's version.  If a bug fix release is made, for instance Automake
1.6.1, the API version will remain 1.6.  This means that a package that
works with Automake 1.6 should also work with 1.6.1; after all, this is
what people expect from bug fix releases.

   If your package relies on a feature or a bug fix introduced in a
release, you can pass this version as an option to Automake to ensure
older releases will not be used.  For instance, use this in your
'configure.ac':

       AM_INIT_AUTOMAKE([1.6.1])    dnl Require Automake 1.6.1 or better.

or, in a particular 'Makefile.am':

       AUTOMAKE_OPTIONS = 1.6.1   # Require Automake 1.6.1 or better.

Automake will print an error message if its version is older than the
requested version.

What is in the API
==================

Automake's programming interface is not easy to define.  Basically it
should include at least all *documented* variables and targets that a
'Makefile.am' author can use, any behavior associated with them (e.g.,
the places where '-hook''s are run), the command line interface of
'automake' and 'aclocal', ...

What is not in the API
======================

Every undocumented variable, target, or command line option, is not part
of the API.  You should avoid using them, as they could change from one
version to the other (even in bug fix releases, if this helps to fix a
bug).

   If it turns out you need to use such an undocumented feature, contact
<automake@gnu.org> and try to get it documented and exercised by the
test-suite.

26 Upgrading a Package to a Newer Automake Version
**************************************************

Automake maintains three kind of files in a package.

   * 'aclocal.m4'
   * 'Makefile.in's
   * auxiliary tools like 'install-sh' or 'py-compile'

   'aclocal.m4' is generated by 'aclocal' and contains some
Automake-supplied M4 macros.  Auxiliary tools are installed by 'automake
--add-missing' when needed.  'Makefile.in's are built from 'Makefile.am'
by 'automake', and rely on the definitions of the M4 macros put in
'aclocal.m4' as well as the behavior of the auxiliary tools installed.

   Because all of these files are closely related, it is important to
regenerate all of them when upgrading to a newer Automake release.  The
usual way to do that is

     aclocal # with any option needed (such a -I m4)
     autoconf
     automake --add-missing --force-missing

or more conveniently:

     autoreconf -vfi

   The use of '--force-missing' ensures that auxiliary tools will be
overridden by new versions (*note automake Invocation::).

   It is important to regenerate all of these files each time Automake
is upgraded, even between bug fixes releases.  For instance, it is not
unusual for a bug fix to involve changes to both the rules generated in
'Makefile.in' and the supporting M4 macros copied to 'aclocal.m4'.

   Presently 'automake' is able to diagnose situations where
'aclocal.m4' has been generated with another version of 'aclocal'.
However it never checks whether auxiliary scripts are up-to-date.  In
other words, 'automake' will tell you when 'aclocal' needs to be rerun,
but it will never diagnose a missing '--force-missing'.

   Before upgrading to a new major release, it is a good idea to read
the file 'NEWS'.  This file lists all changes between releases: new
features, obsolete constructs, known incompatibilities, and workarounds.

27 Frequently Asked Questions about Automake
********************************************

This chapter covers some questions that often come up on the mailing
lists.

27.1 CVS and generated files
============================

Background: distributed generated Files
---------------------------------------

Packages made with Autoconf and Automake ship with some generated files
like 'configure' or 'Makefile.in'.  These files were generated on the
developer's machine and are distributed so that end-users do not have to
install the maintainer tools required to rebuild them.  Other generated
files like Lex scanners, Yacc parsers, or Info documentation, are
usually distributed on similar grounds.

   Automake output rules in 'Makefile's to rebuild these files.  For
instance, 'make' will run 'autoconf' to rebuild 'configure' whenever
'configure.ac' is changed.  This makes development safer by ensuring a
'configure' is never out-of-date with respect to 'configure.ac'.

   As generated files shipped in packages are up-to-date, and because
'tar' preserves times-tamps, these rebuild rules are not triggered when
a user unpacks and builds a package.

Background: CVS and Timestamps
------------------------------

Unless you use CVS keywords (in which case files must be updated at
commit time), CVS preserves timestamp during 'cvs commit' and 'cvs
import -d' operations.

   When you check out a file using 'cvs checkout' its timestamp is set
to that of the revision that is being checked out.

   However, during 'cvs update', files will have the date of the update,
not the original timestamp of this revision.  This is meant to make sure
that 'make' notices sources files have been updated.

   This timestamp shift is troublesome when both sources and generated
files are kept under CVS.  Because CVS processes files in lexical order,
'configure.ac' will appear newer than 'configure' after a 'cvs update'
that updates both files, even if 'configure' was newer than
'configure.ac' when it was checked in.  Calling 'make' will then trigger
a spurious rebuild of 'configure'.

Living with CVS in Autoconfiscated Projects
-------------------------------------------

There are basically two clans amongst maintainers: those who keep all
distributed files under CVS, including generated files, and those who
keep generated files _out_ of CVS.

All Files in CVS
................

   * The CVS repository contains all distributed files so you know
     exactly what is distributed, and you can checkout any prior version
     entirely.

   * Maintainers can see how generated files evolve (for instance, you
     can see what happens to your 'Makefile.in's when you upgrade
     Automake and make sure they look OK).

   * Users do not need the autotools to build a checkout of the project,
     it works just like a released tarball.

   * If users use 'cvs update' to update their copy, instead of 'cvs
     checkout' to fetch a fresh one, timestamps will be inaccurate.
     Some rebuild rules will be triggered and attempt to run developer
     tools such as 'autoconf' or 'automake'.

     Calls to such tools are all wrapped into a call to the 'missing'
     script discussed later (*note maintainer-mode::), so that the user
     will see more descriptive warnings about missing or out-of-date
     tools, and possible suggestions about how to obtain them, rather
     than just some "command not found" error, or (worse) some obscure
     message from some older version of the required tool they happen to
     have installed.

     Maintainers interested in keeping their package buildable from a
     CVS checkout even for those users that lack maintainer-specific
     tools might want to provide an helper script (or to enhance their
     existing bootstrap script) to fix the timestamps after a 'cvs
     update' or a 'git checkout', to prevent spurious rebuilds.  In case
     of a project committing the Autotools-generated files, as well as
     the generated '.info' files, such script might look something like
     this:

          #!/bin/sh
          # fix-timestamp.sh: prevents useless rebuilds after "cvs update"
          sleep 1
          # aclocal-generated aclocal.m4 depends on locally-installed
          # '.m4' macro files, as well as on 'configure.ac'
          touch aclocal.m4
          sleep 1
          # autoconf-generated configure depends on aclocal.m4 and on
          # configure.ac
          touch configure
          # so does autoheader-generated config.h.in
          touch config.h.in
          # and all the automake-generated Makefile.in files
          touch `find . -name Makefile.in -print`
          # finally, the makeinfo-generated '.info' files depend on the
          # corresponding '.texi' files
          touch doc/*.info

   * In distributed development, developers are likely to have different
     version of the maintainer tools installed.  In this case rebuilds
     triggered by timestamp lossage will lead to spurious changes to
     generated files.  There are several solutions to this:

        * All developers should use the same versions, so that the
          rebuilt files are identical to files in CVS.  (This starts to
          be difficult when each project you work on uses different
          versions.)
        * Or people use a script to fix the timestamp after a checkout
          (the GCC folks have such a script).
        * Or 'configure.ac' uses 'AM_MAINTAINER_MODE', which will
          disable all of these rebuild rules by default.  This is
          further discussed in *note maintainer-mode::.

   * Although we focused on spurious rebuilds, the converse can also
     happen.  CVS's timestamp handling can also let you think an
     out-of-date file is up-to-date.

     For instance, suppose a developer has modified 'Makefile.am' and
     has rebuilt 'Makefile.in', and then decides to do a last-minute
     change to 'Makefile.am' right before checking in both files
     (without rebuilding 'Makefile.in' to account for the change).

     This last change to 'Makefile.am' makes the copy of 'Makefile.in'
     out-of-date.  Since CVS processes files alphabetically, when
     another developer 'cvs update's his or her tree, 'Makefile.in' will
     happen to be newer than 'Makefile.am'.  This other developer will
     not see that 'Makefile.in' is out-of-date.

Generated Files out of CVS
..........................

One way to get CVS and 'make' working peacefully is to never store
generated files in CVS, i.e., do not CVS-control files that are
'Makefile' targets (also called _derived_ files).

   This way developers are not annoyed by changes to generated files.
It does not matter if they all have different versions (assuming they
are compatible, of course).  And finally, timestamps are not lost,
changes to sources files can't be missed as in the
'Makefile.am'/'Makefile.in' example discussed earlier.

   The drawback is that the CVS repository is not an exact copy of what
is distributed and that users now need to install various development
tools (maybe even specific versions) before they can build a checkout.
But, after all, CVS's job is versioning, not distribution.

   Allowing developers to use different versions of their tools can also
hide bugs during distributed development.  Indeed, developers will be
using (hence testing) their own generated files, instead of the
generated files that will be released actually.  The developer who
prepares the tarball might be using a version of the tool that produces
bogus output (for instance a non-portable C file), something other
developers could have noticed if they weren't using their own versions
of this tool.

Third-party Files
-----------------

Another class of files not discussed here (because they do not cause
timestamp issues) are files that are shipped with a package, but
maintained elsewhere.  For instance, tools like 'gettextize' and
'autopoint' (from Gettext) or 'libtoolize' (from Libtool), will install
or update files in your package.

   These files, whether they are kept under CVS or not, raise similar
concerns about version mismatch between developers' tools.  The Gettext
manual has a section about this, see *note CVS Issues: (gettext)CVS
Issues.

27.2 'missing' and 'AM_MAINTAINER_MODE'
=======================================

'missing'
---------

The 'missing' script is a wrapper around several maintainer tools,
designed to warn users if a maintainer tool is required but missing.
Typical maintainer tools are 'autoconf', 'automake', 'bison', etc.
Because file generated by these tools are shipped with the other sources
of a package, these tools shouldn't be required during a user build and
they are not checked for in 'configure'.

   However, if for some reason a rebuild rule is triggered and involves
a missing tool, 'missing' will notice it and warn the user, even
suggesting how to obtain such a tool (at least in case it is a
well-known one, like 'makeinfo' or 'bison').  This is more helpful and
user-friendly than just having the rebuild rules spewing out a terse
error message like 'sh: TOOL: command not found'.  Similarly, 'missing'
will warn the user if it detects that a maintainer tool it attempted to
use seems too old (be warned that diagnosing this correctly is typically
more difficult that detecting missing tools, and requires cooperation
from the tool itself, so it won't always work).

   If the required tool is installed, 'missing' will run it and won't
attempt to continue after failures.  This is correct during development:
developers love fixing failures.  However, users with missing or too old
maintainer tools may get an error when the rebuild rule is spuriously
triggered, halting the build.  This failure to let the build continue is
one of the arguments of the 'AM_MAINTAINER_MODE' advocates.

'AM_MAINTAINER_MODE'
--------------------

'AM_MAINTAINER_MODE' allows you to choose whether the so called "rebuild
rules" should be enabled or disabled.  With
'AM_MAINTAINER_MODE([enable])', they are enabled by default, otherwise
they are disabled by default.  In the latter case, if you have
'AM_MAINTAINER_MODE' in 'configure.ac', and run './configure && make',
then 'make' will *never* attempt to rebuild 'configure', 'Makefile.in's,
Lex or Yacc outputs, etc.  I.e., this disables build rules for files
that are usually distributed and that users should normally not have to
update.

   The user can override the default setting by passing either
'--enable-maintainer-mode' or '--disable-maintainer-mode' to
'configure'.

   People use 'AM_MAINTAINER_MODE' either because they do not want their
users (or themselves) annoyed by timestamps lossage (*note CVS::), or
because they simply can't stand the rebuild rules and prefer running
maintainer tools explicitly.

   'AM_MAINTAINER_MODE' also allows you to disable some custom build
rules conditionally.  Some developers use this feature to disable rules
that need exotic tools that users may not have available.

   Several years ago Franc,ois Pinard pointed out several arguments
against this 'AM_MAINTAINER_MODE' macro.  Most of them relate to
insecurity.  By removing dependencies you get non-dependable builds:
changes to sources files can have no effect on generated files and this
can be very confusing when unnoticed.  He adds that security shouldn't
be reserved to maintainers (what '--enable-maintainer-mode' suggests),
on the contrary.  If one user has to modify a 'Makefile.am', then either
'Makefile.in' should be updated or a warning should be output (this is
what Automake uses 'missing' for) but the last thing you want is that
nothing happens and the user doesn't notice it (this is what happens
when rebuild rules are disabled by 'AM_MAINTAINER_MODE').

   Jim Meyering, the inventor of the 'AM_MAINTAINER_MODE' macro was
swayed by Franc,ois's arguments, and got rid of 'AM_MAINTAINER_MODE' in
all of his packages.

   Still many people continue to use 'AM_MAINTAINER_MODE', because it
helps them working on projects where all files are kept under version
control, and because 'missing' isn't enough if you have the wrong
version of the tools.

27.3 Why doesn't Automake support wildcards?
============================================

Developers are lazy.  They would often like to use wildcards in
'Makefile.am's, so that they would not need to remember to update
'Makefile.am's every time they add, delete, or rename a file.

   There are several objections to this:
   * When using CVS (or similar) developers need to remember they have
     to run 'cvs add' or 'cvs rm' anyway.  Updating 'Makefile.am'
     accordingly quickly becomes a reflex.

     Conversely, if your application doesn't compile because you forgot
     to add a file in 'Makefile.am', it will help you remember to 'cvs
     add' it.

   * Using wildcards makes it easy to distribute files by mistake.  For
     instance, some code a developer is experimenting with (a test case,
     say) that should not be part of the distribution.

   * Using wildcards it's easy to omit some files by mistake.  For
     instance, one developer creates a new file, uses it in many places,
     but forgets to commit it.  Another developer then checks out the
     incomplete project and is able to run 'make dist' successfully,
     even though a file is missing.  By listing files, 'make dist'
     _will_ complain.

   * Wildcards are not portable to some non-GNU 'make' implementations,
     e.g., NetBSD 'make' will not expand globs such as '*' in
     prerequisites of a target.

   * Finally, it's really hard to _forget_ to add a file to
     'Makefile.am': files that are not listed in 'Makefile.am' are not
     compiled or installed, so you can't even test them.

   Still, these are philosophical objections, and as such you may
disagree, or find enough value in wildcards to dismiss all of them.
Before you start writing a patch against Automake to teach it about
wildcards, let's see the main technical issue: portability.

   Although '$(wildcard ...)' works with GNU 'make', it is not portable
to other 'make' implementations.

   The only way Automake could support '$(wildcard ...)' is by expanding
'$(wildcard ...)' when 'automake' is run.  The resulting 'Makefile.in's
would be portable since they would list all files and not use
'$(wildcard ...)'.  However that means developers would need to remember
to run 'automake' each time they add, delete, or rename files.

   Compared to editing 'Makefile.am', this is a very small gain.  Sure,
it's easier and faster to type 'automake; make' than to type 'emacs
Makefile.am; make'.  But nobody bothered enough to write a patch to add
support for this syntax.  Some people use scripts to generate file lists
in 'Makefile.am' or in separate 'Makefile' fragments.

   Even if you don't care about portability, and are tempted to use
'$(wildcard ...)' anyway because you target only GNU Make, you should
know there are many places where Automake needs to know exactly which
files should be processed.  As Automake doesn't know how to expand
'$(wildcard ...)', you cannot use it in these places.  '$(wildcard ...)'
is a black box comparable to 'AC_SUBST'ed variables as far Automake is
concerned.

   You can get warnings about '$(wildcard ...') constructs using the
'-Wportability' flag.

27.4 Limitations on File Names
==============================

Automake attempts to support all kinds of file names, even those that
contain unusual characters or are unusually long.  However, some
limitations are imposed by the underlying operating system and tools.

   Most operating systems prohibit the use of the null byte in file
names, and reserve '/' as a directory separator.  Also, they require
that file names are properly encoded for the user's locale.  Automake is
subject to these limits.

   Portable packages should limit themselves to POSIX file names.  These
can contain ASCII letters and digits, '_', '.', and '-'.  File names
consist of components separated by '/'.  File name components cannot
begin with '-'.

   Portable POSIX file names cannot contain components that exceed a
14-byte limit, but nowadays it's normally safe to assume the
more-generous XOPEN limit of 255 bytes.  POSIX limits file names to 255
bytes (XOPEN allows 1023 bytes), but you may want to limit a source
tarball to file names of 99 bytes to avoid interoperability problems
with old versions of 'tar'.

   If you depart from these rules (e.g., by using non-ASCII characters
in file names, or by using lengthy file names), your installers may have
problems for reasons unrelated to Automake.  However, if this does not
concern you, you should know about the limitations imposed by Automake
itself.  These limitations are undesirable, but some of them seem to be
inherent to underlying tools like Autoconf, Make, M4, and the shell.
They fall into three categories: install directories, build directories,
and file names.

   The following characters:

     newline " # $ ' `

   should not appear in the names of install directories.  For example,
the operand of 'configure''s '--prefix' option should not contain these
characters.

   Build directories suffer the same limitations as install directories,
and in addition should not contain the following characters:

     & @ 

   For example, the full name of the directory containing the source
files should not contain these characters.

   Source and installation file names like 'main.c' are limited even
further: they should conform to the POSIX/XOPEN rules described above.
In addition, if you plan to port to non-POSIX environments, you should
avoid file names that differ only in case (e.g., 'makefile' and
'Makefile').  Nowadays it is no longer worth worrying about the 8.3
limits of DOS file systems.

27.5 Errors with distclean
==========================

This is a diagnostic you might encounter while running 'make distcheck'.

   As explained in *note Checking the Distribution::, 'make distcheck'
attempts to build and check your package for errors like this one.

   'make distcheck' will perform a 'VPATH' build of your package (*note
VPATH Builds::), and then call 'make distclean'.  Files left in the
build directory after 'make distclean' has run are listed after this
error.

   This diagnostic really covers two kinds of errors:

   * files that are forgotten by distclean;
   * distributed files that are erroneously rebuilt.

   The former left-over files are not distributed, so the fix is to mark
them for cleaning (*note Clean::), this is obvious and doesn't deserve
more explanations.

   The latter bug is not always easy to understand and fix, so let's
proceed with an example.  Suppose our package contains a program for
which we want to build a man page using 'help2man'.  GNU 'help2man'
produces simple manual pages from the '--help' and '--version' output of
other commands (*note Overview: (help2man)Top.).  Because we don't want
to force our users to install 'help2man', we decide to distribute the
generated man page using the following setup.

     # This Makefile.am is bogus.
     bin_PROGRAMS = foo
     foo_SOURCES = foo.c
     dist_man_MANS = foo.1

     foo.1: foo$(EXEEXT)
             help2man --output=foo.1 ./foo$(EXEEXT)

   This will effectively distribute the man page.  However, 'make
distcheck' will fail with:

     ERROR: files left in build directory after distclean:
     ./foo.1

   Why was 'foo.1' rebuilt?  Because although distributed, 'foo.1'
depends on a non-distributed built file: 'foo$(EXEEXT)'.  'foo$(EXEEXT)'
is built by the user, so it will always appear to be newer than the
distributed 'foo.1'.

   'make distcheck' caught an inconsistency in our package.  Our intent
was to distribute 'foo.1' so users do not need to install 'help2man',
however since this rule causes this file to be always rebuilt, users
_do_ need 'help2man'.  Either we should ensure that 'foo.1' is not
rebuilt by users, or there is no point in distributing 'foo.1'.

   More generally, the rule is that distributed files should never
depend on non-distributed built files.  If you distribute something
generated, distribute its sources.

   One way to fix the above example, while still distributing 'foo.1' is
to not depend on 'foo$(EXEEXT)'.  For instance, assuming 'foo --version'
and 'foo --help' do not change unless 'foo.c' or 'configure.ac' change,
we could write the following 'Makefile.am':

     bin_PROGRAMS = foo
     foo_SOURCES = foo.c
     dist_man_MANS = foo.1

     foo.1: foo.c $(top_srcdir)/configure.ac
             $(MAKE) $(AM_MAKEFLAGS) foo$(EXEEXT)
             help2man --output=foo.1 ./foo$(EXEEXT)

   This way, 'foo.1' will not get rebuilt every time 'foo$(EXEEXT)'
changes.  The 'make' call makes sure 'foo$(EXEEXT)' is up-to-date before
'help2man'.  Another way to ensure this would be to use separate
directories for binaries and man pages, and set 'SUBDIRS' so that
binaries are built before man pages.

   We could also decide not to distribute 'foo.1'.  In this case it's
fine to have 'foo.1' dependent upon 'foo$(EXEEXT)', since both will have
to be rebuilt.  However it would be impossible to build the package in a
cross-compilation, because building 'foo.1' involves an _execution_ of
'foo$(EXEEXT)'.

   Another context where such errors are common is when distributed
files are built by tools that are built by the package.  The pattern is
similar:

     distributed-file: built-tools distributed-sources
             build-command

should be changed to

     distributed-file: distributed-sources
             $(MAKE) $(AM_MAKEFLAGS) built-tools
             build-command

or you could choose not to distribute 'distributed-file', if
cross-compilation does not matter.

   The points made through these examples are worth a summary:

   * Distributed files should never depend upon non-distributed built
     files.
   * Distributed files should be distributed with all their
     dependencies.
   * If a file is _intended_ to be rebuilt by users, then there is no
     point in distributing it.

   For desperate cases, it's always possible to disable this check by
setting 'distcleancheck_listfiles' as documented in *note Checking the
Distribution::.  Make sure you do understand the reason why 'make
distcheck' complains before you do this.  'distcleancheck_listfiles' is
a way to _hide_ errors, not to fix them.  You can always do better.

27.6 Flag Variables Ordering
============================

     What is the difference between 'AM_CFLAGS', 'CFLAGS', and
     'mumble_CFLAGS'?

     Why does 'automake' output 'CPPFLAGS' after
     'AM_CPPFLAGS' on compile lines?  Shouldn't it be the converse?

     My 'configure' adds some warning flags into 'CXXFLAGS'.  In
     one 'Makefile.am' I would like to append a new flag, however if I
     put the flag into 'AM_CXXFLAGS' it is prepended to the other
     flags, not appended.

Compile Flag Variables
----------------------

This section attempts to answer all the above questions.  We will mostly
discuss 'CPPFLAGS' in our examples, but actually the answer holds for
all the compile flags used in Automake: 'CCASFLAGS', 'CFLAGS',
'CPPFLAGS', 'CXXFLAGS', 'FCFLAGS', 'FFLAGS', 'GCJFLAGS', 'LDFLAGS',
'LFLAGS', 'LIBTOOLFLAGS', 'OBJCFLAGS', 'OBJCXXFLAGS', 'RFLAGS',
'UPCFLAGS', and 'YFLAGS'.

   'CPPFLAGS', 'AM_CPPFLAGS', and 'mumble_CPPFLAGS' are three variables
that can be used to pass flags to the C preprocessor (actually these
variables are also used for other languages like C++ or preprocessed
Fortran).  'CPPFLAGS' is the user variable (*note User Variables::),
'AM_CPPFLAGS' is the Automake variable, and 'mumble_CPPFLAGS' is the
variable specific to the 'mumble' target (we call this a per-target
variable, *note Program and Library Variables::).

   Automake always uses two of these variables when compiling C sources
files.  When compiling an object file for the 'mumble' target, the first
variable will be 'mumble_CPPFLAGS' if it is defined, or 'AM_CPPFLAGS'
otherwise.  The second variable is always 'CPPFLAGS'.

   In the following example,

     bin_PROGRAMS = foo bar
     foo_SOURCES = xyz.c
     bar_SOURCES = main.c
     foo_CPPFLAGS = -DFOO
     AM_CPPFLAGS = -DBAZ

'xyz.o' will be compiled with '$(foo_CPPFLAGS) $(CPPFLAGS)', (because
'xyz.o' is part of the 'foo' target), while 'main.o' will be compiled
with '$(AM_CPPFLAGS) $(CPPFLAGS)' (because there is no per-target
variable for target 'bar').

   The difference between 'mumble_CPPFLAGS' and 'AM_CPPFLAGS' being
clear enough, let's focus on 'CPPFLAGS'.  'CPPFLAGS' is a user variable,
i.e., a variable that users are entitled to modify in order to compile
the package.  This variable, like many others, is documented at the end
of the output of 'configure --help'.

   For instance, someone who needs to add '/home/my/usr/include' to the
C compiler's search path would configure a package with

     ./configure CPPFLAGS='-I /home/my/usr/include'

and this flag would be propagated to the compile rules of all
'Makefile's.

   It is also not uncommon to override a user variable at 'make'-time.
Many installers do this with 'prefix', but this can be useful with
compiler flags too.  For instance, if, while debugging a C++ project,
you need to disable optimization in one specific object file, you can
run something like

     rm file.o
     make CXXFLAGS=-O0 file.o
     make

   The reason '$(CPPFLAGS)' appears after '$(AM_CPPFLAGS)' or
'$(mumble_CPPFLAGS)' in the compile command is that users should always
have the last say.  It probably makes more sense if you think about it
while looking at the 'CXXFLAGS=-O0' above, which should supersede any
other switch from 'AM_CXXFLAGS' or 'mumble_CXXFLAGS' (and this of course
replaces the previous value of 'CXXFLAGS').

   You should never redefine a user variable such as 'CPPFLAGS' in
'Makefile.am'.  Use 'automake -Woverride' to diagnose such mistakes.
Even something like

     CPPFLAGS = -DDATADIR="$(datadir)" @CPPFLAGS@

is erroneous.  Although this preserves 'configure''s value of
'CPPFLAGS', the definition of 'DATADIR' will disappear if a user
attempts to override 'CPPFLAGS' from the 'make' command line.

     AM_CPPFLAGS = -DDATADIR="$(datadir)"

is all that is needed here if no per-target flags are used.

   You should not add options to these user variables within 'configure'
either, for the same reason.  Occasionally you need to modify these
variables to perform a test, but you should reset their values
afterwards.  In contrast, it is OK to modify the 'AM_' variables within
'configure' if you 'AC_SUBST' them, but it is rather rare that you need
to do this, unless you really want to change the default definitions of
the 'AM_' variables in all 'Makefile's.

   What we recommend is that you define extra flags in separate
variables.  For instance, you may write an Autoconf macro that computes
a set of warning options for the C compiler, and 'AC_SUBST' them in
'WARNINGCFLAGS'; you may also have an Autoconf macro that determines
which compiler and which linker flags should be used to link with
library 'libfoo', and 'AC_SUBST' these in 'LIBFOOCFLAGS' and
'LIBFOOLDFLAGS'.  Then, a 'Makefile.am' could use these variables as
follows:

     AM_CFLAGS = $(WARNINGCFLAGS)
     bin_PROGRAMS = prog1 prog2
     prog1_SOURCES = ...
     prog2_SOURCES = ...
     prog2_CFLAGS = $(LIBFOOCFLAGS) $(AM_CFLAGS)
     prog2_LDFLAGS = $(LIBFOOLDFLAGS)

   In this example both programs will be compiled with the flags
substituted into '$(WARNINGCFLAGS)', and 'prog2' will additionally be
compiled with the flags required to link with 'libfoo'.

   Note that listing 'AM_CFLAGS' in a per-target 'CFLAGS' variable is a
common idiom to ensure that 'AM_CFLAGS' applies to every target in a
'Makefile.in'.

   Using variables like this gives you full control over the ordering of
the flags.  For instance, if there is a flag in $(WARNINGCFLAGS) that
you want to negate for a particular target, you can use something like
'prog1_CFLAGS = $(AM_CFLAGS) -no-flag'.  If all of these flags had been
forcefully appended to 'CFLAGS', there would be no way to disable one
flag.  Yet another reason to leave user variables to users.

   Finally, we have avoided naming the variable of the example
'LIBFOO_LDFLAGS' (with an underscore) because that would cause Automake
to think that this is actually a per-target variable (like
'mumble_LDFLAGS') for some non-declared 'LIBFOO' target.

Other Variables
---------------

There are other variables in Automake that follow similar principles to
allow user options.  For instance, Texinfo rules (*note Texinfo::) use
'MAKEINFOFLAGS' and 'AM_MAKEINFOFLAGS'.  Similarly, DejaGnu tests (*note
DejaGnu Tests::) use 'RUNTESTDEFAULTFLAGS' and 'AM_RUNTESTDEFAULTFLAGS'.
The tags and ctags rules (*note Tags::) use 'ETAGSFLAGS',
'AM_ETAGSFLAGS', 'CTAGSFLAGS', and 'AM_CTAGSFLAGS'.  Java rules (*note
Java::) use 'JAVACFLAGS' and 'AM_JAVACFLAGS'.  None of these rules
support per-target flags (yet).

   To some extent, even 'AM_MAKEFLAGS' (*note Subdirectories::) obeys
this naming scheme.  The slight difference is that 'MAKEFLAGS' is passed
to sub-'make's implicitly by 'make' itself.

   'ARFLAGS' (*note A Library::) is usually defined by Automake and has
neither 'AM_' nor per-target cousin.

   Finally you should not think that the existence of a per-target
variable implies the existence of an 'AM_' variable or of a user
variable.  For instance, the 'mumble_LDADD' per-target variable
overrides the makefile-wide 'LDADD' variable (which is not a user
variable), and 'mumble_LIBADD' exists only as a per-target variable.
*Note Program and Library Variables::.

27.7 Why are object files sometimes renamed?
============================================

This happens when per-target compilation flags are used.  Object files
need to be renamed just in case they would clash with object files
compiled from the same sources, but with different flags.  Consider the
following example.

     bin_PROGRAMS = true false
     true_SOURCES = generic.c
     true_CPPFLAGS = -DEXIT_CODE=0
     false_SOURCES = generic.c
     false_CPPFLAGS = -DEXIT_CODE=1

Obviously the two programs are built from the same source, but it would
be bad if they shared the same object, because 'generic.o' cannot be
built with both '-DEXIT_CODE=0' _and_ '-DEXIT_CODE=1'.  Therefore
'automake' outputs rules to build two different objects:
'true-generic.o' and 'false-generic.o'.

   'automake' doesn't actually look whether source files are shared to
decide if it must rename objects.  It will just rename all objects of a
target as soon as it sees per-target compilation flags used.

   It's OK to share object files when per-target compilation flags are
not used.  For instance, 'true' and 'false' will both use 'version.o' in
the following example.

     AM_CPPFLAGS = -DVERSION=1.0
     bin_PROGRAMS = true false
     true_SOURCES = true.c version.c
     false_SOURCES = false.c version.c

   Note that the renaming of objects is also affected by the
'_SHORTNAME' variable (*note Program and Library Variables::).

27.8 Per-Object Flags Emulation
===============================

     One of my source files needs to be compiled with different flags.  How
     do I do?

   Automake supports per-program and per-library compilation flags (see
*note Program and Library Variables:: and *note Flag Variables
Ordering::).  With this you can define compilation flags that apply to
all files compiled for a target.  For instance, in

     bin_PROGRAMS = foo
     foo_SOURCES = foo.c foo.h bar.c bar.h main.c
     foo_CFLAGS = -some -flags

'foo-foo.o', 'foo-bar.o', and 'foo-main.o' will all be compiled with
'-some -flags'.  (If you wonder about the names of these object files,
see *note Renamed Objects::.)  Note that 'foo_CFLAGS' gives the flags to
use when compiling all the C sources of the _program_ 'foo', it has
nothing to do with 'foo.c' or 'foo-foo.o' specifically.

   What if 'foo.c' needs to be compiled into 'foo.o' using some specific
flags, that none of the other files requires?  Obviously per-program
flags are not directly applicable here.  Something like per-object flags
are expected, i.e., flags that would be used only when creating
'foo-foo.o'.  Automake does not support that, however this is easy to
simulate using a library that contains only that object, and compiling
this library with per-library flags.

     bin_PROGRAMS = foo
     foo_SOURCES = bar.c bar.h main.c
     foo_CFLAGS = -some -flags
     foo_LDADD = libfoo.a
     noinst_LIBRARIES = libfoo.a
     libfoo_a_SOURCES = foo.c foo.h
     libfoo_a_CFLAGS = -some -other -flags

   Here 'foo-bar.o' and 'foo-main.o' will all be compiled with '-some
-flags', while 'libfoo_a-foo.o' will be compiled using '-some -other
-flags'.  Eventually, all three objects will be linked to form 'foo'.

   This trick can also be achieved using Libtool convenience libraries,
for instance 'noinst_LTLIBRARIES = libfoo.la' (*note Libtool Convenience
Libraries::).

   Another tempting idea to implement per-object flags is to override
the compile rules 'automake' would output for these files.  Automake
will not define a rule for a target you have defined, so you could think
about defining the 'foo-foo.o: foo.c' rule yourself.  We recommend
against this, because this is error prone.  For instance, if you add
such a rule to the first example, it will break the day you decide to
remove 'foo_CFLAGS' (because 'foo.c' will then be compiled as 'foo.o'
instead of 'foo-foo.o', *note Renamed Objects::).  Also in order to
support dependency tracking, the two '.o'/'.obj' extensions, and all the
other flags variables involved in a compilation, you will end up
modifying a copy of the rule previously output by 'automake' for this
file.  If a new release of Automake generates a different rule, your
copy will need to be updated by hand.

27.9 Handling Tools that Produce Many Outputs
=============================================

This section describes a 'make' idiom that can be used when a tool
produces multiple output files.  It is not specific to Automake and can
be used in ordinary 'Makefile's.

   Suppose we have a program called 'foo' that will read one file called
'data.foo' and produce two files named 'data.c' and 'data.h'.  We want
to write a 'Makefile' rule that captures this one-to-two dependency.

   The naive rule is incorrect:

     # This is incorrect.
     data.c data.h: data.foo
             foo data.foo

What the above rule really says is that 'data.c' and 'data.h' each
depend on 'data.foo', and can each be built by running 'foo data.foo'.
In other words it is equivalent to:

     # We do not want this.
     data.c: data.foo
             foo data.foo
     data.h: data.foo
             foo data.foo

which means that 'foo' can be run twice.  Usually it will not be run
twice, because 'make' implementations are smart enough to check for the
existence of the second file after the first one has been built; they
will therefore detect that it already exists.  However there are a few
situations where it can run twice anyway:

   * The most worrying case is when running a parallel 'make'.  If
     'data.c' and 'data.h' are built in parallel, two 'foo data.foo'
     commands will run concurrently.  This is harmful.
   * Another case is when the dependency (here 'data.foo') is (or
     depends upon) a phony target.

   A solution that works with parallel 'make' but not with phony
dependencies is the following:

     data.c data.h: data.foo
             foo data.foo
     data.h: data.c

The above rules are equivalent to

     data.c: data.foo
             foo data.foo
     data.h: data.foo data.c
             foo data.foo

therefore a parallel 'make' will have to serialize the builds of
'data.c' and 'data.h', and will detect that the second is no longer
needed once the first is over.

   Using this pattern is probably enough for most cases.  However it
does not scale easily to more output files (in this scheme all output
files must be totally ordered by the dependency relation), so we will
explore a more complicated solution.

   Another idea is to write the following:

     # There is still a problem with this one.
     data.c: data.foo
             foo data.foo
     data.h: data.c

The idea is that 'foo data.foo' is run only when 'data.c' needs to be
updated, but we further state that 'data.h' depends upon 'data.c'.  That
way, if 'data.h' is required and 'data.foo' is out of date, the
dependency on 'data.c' will trigger the build.

   This is almost perfect, but suppose we have built 'data.h' and
'data.c', and then we erase 'data.h'.  Then, running 'make data.h' will
not rebuild 'data.h'.  The above rules just state that 'data.c' must be
up-to-date with respect to 'data.foo', and this is already the case.

   What we need is a rule that forces a rebuild when 'data.h' is
missing.  Here it is:

     data.c: data.foo
             foo data.foo
     data.h: data.c
     ## Recover from the removal of $@
             @if test -f $@; then :; else 
               rm -f data.c; 
               $(MAKE) $(AM_MAKEFLAGS) data.c; 
             fi

   The above scheme can be extended to handle more outputs and more
inputs.  One of the outputs is selected to serve as a witness to the
successful completion of the command, it depends upon all inputs, and
all other outputs depend upon it.  For instance, if 'foo' should
additionally read 'data.bar' and also produce 'data.w' and 'data.x', we
would write:

     data.c: data.foo data.bar
             foo data.foo data.bar
     data.h data.w data.x: data.c
     ## Recover from the removal of $@
             @if test -f $@; then :; else 
               rm -f data.c; 
               $(MAKE) $(AM_MAKEFLAGS) data.c; 
             fi

   However there are now three minor problems in this setup.  One is
related to the timestamp ordering of 'data.h', 'data.w', 'data.x', and
'data.c'.  Another one is a race condition if a parallel 'make' attempts
to run multiple instances of the recover block at once.  Finally, the
recursive rule breaks 'make -n' when run with GNU 'make' (as well as
some other 'make' implementations), as it may remove 'data.h' even when
it should not (*note How the 'MAKE' Variable Works: (make)MAKE
Variable.).

   Let us deal with the first problem.  'foo' outputs four files, but we
do not know in which order these files are created.  Suppose that
'data.h' is created before 'data.c'.  Then we have a weird situation.
The next time 'make' is run, 'data.h' will appear older than 'data.c',
the second rule will be triggered, a shell will be started to execute
the 'if...fi' command, but actually it will just execute the 'then'
branch, that is: nothing.  In other words, because the witness we
selected is not the first file created by 'foo', 'make' will start a
shell to do nothing each time it is run.

   A simple riposte is to fix the timestamps when this happens.

     data.c: data.foo data.bar
             foo data.foo data.bar
     data.h data.w data.x: data.c
             @if test -f $@; then 
               touch $@; 
             else 
     ## Recover from the removal of $@
               rm -f data.c; 
               $(MAKE) $(AM_MAKEFLAGS) data.c; 
             fi

   Another solution is to use a different and dedicated file as witness,
rather than using any of 'foo''s outputs.

     data.stamp: data.foo data.bar
             @rm -f data.tmp
             @touch data.tmp
             foo data.foo data.bar
             @mv -f data.tmp $@
     data.c data.h data.w data.x: data.stamp
     ## Recover from the removal of $@
             @if test -f $@; then :; else 
               rm -f data.stamp; 
               $(MAKE) $(AM_MAKEFLAGS) data.stamp; 
             fi

   'data.tmp' is created before 'foo' is run, so it has a timestamp
older than output files output by 'foo'.  It is then renamed to
'data.stamp' after 'foo' has run, because we do not want to update
'data.stamp' if 'foo' fails.

   This solution still suffers from the second problem: the race
condition in the recover rule.  If, after a successful build, a user
erases 'data.c' and 'data.h', and runs 'make -j', then 'make' may start
both recover rules in parallel.  If the two instances of the rule
execute '$(MAKE) $(AM_MAKEFLAGS) data.stamp' concurrently the build is
likely to fail (for instance, the two rules will create 'data.tmp', but
only one can rename it).

   Admittedly, such a weird situation does not arise during ordinary
builds.  It occurs only when the build tree is mutilated.  Here 'data.c'
and 'data.h' have been explicitly removed without also removing
'data.stamp' and the other output files.  'make clean; make' will always
recover from these situations even with parallel makes, so you may
decide that the recover rule is solely to help non-parallel make users
and leave things as-is.  Fixing this requires some locking mechanism to
ensure only one instance of the recover rule rebuilds 'data.stamp'.  One
could imagine something along the following lines.

     data.c data.h data.w data.x: data.stamp
     ## Recover from the removal of $@
             @if test -f $@; then :; else 
               trap 'rm -rf data.lock data.stamp' 1 2 13 15; 
     ## mkdir is a portable test-and-set
               if mkdir data.lock 2>/dev/null; then 
     ## This code is being executed by the first process.
                 rm -f data.stamp; 
                 $(MAKE) $(AM_MAKEFLAGS) data.stamp; 
                 result=$$?; rm -rf data.lock; exit $$result; 
               else 
     ## This code is being executed by the follower processes.
     ## Wait until the first process is done.
                 while test -d data.lock; do sleep 1; done; 
     ## Succeed if and only if the first process succeeded.
                 test -f data.stamp; 
               fi; 
             fi

   Using a dedicated witness, like 'data.stamp', is very handy when the
list of output files is not known beforehand.  As an illustration,
consider the following rules to compile many '*.el' files into '*.elc'
files in a single command.  It does not matter how 'ELFILES' is defined
(as long as it is not empty: empty targets are not accepted by POSIX).

     ELFILES = one.el two.el three.el ...
     ELCFILES = $(ELFILES:=c)

     elc-stamp: $(ELFILES)
             @rm -f elc-temp
             @touch elc-temp
             $(elisp_comp) $(ELFILES)
             @mv -f elc-temp $@

     $(ELCFILES): elc-stamp
             @if test -f $@; then :; else 
     ## Recover from the removal of $@
               trap 'rm -rf elc-lock elc-stamp' 1 2 13 15; 
               if mkdir elc-lock 2>/dev/null; then 
     ## This code is being executed by the first process.
                 rm -f elc-stamp; 
                 $(MAKE) $(AM_MAKEFLAGS) elc-stamp; 
                 rmdir elc-lock; 
               else 
     ## This code is being executed by the follower processes.
     ## Wait until the first process is done.
                 while test -d elc-lock; do sleep 1; done; 
     ## Succeed if and only if the first process succeeded.
                 test -f elc-stamp; exit $$?; 
               fi; 
             fi

   These solutions all still suffer from the third problem, namely that
they break the promise that 'make -n' should not cause any actual
changes to the tree.  For those solutions that do not create lock files,
it is possible to split the recover rules into two separate recipe
commands, one of which does all work but the recursion, and the other
invokes the recursive '$(MAKE)'.  The solutions involving locking could
act upon the contents of the 'MAKEFLAGS' variable, but parsing that
portably is not easy (*note (autoconf)The Make Macro MAKEFLAGS::).  Here
is an example:

     ELFILES = one.el two.el three.el ...
     ELCFILES = $(ELFILES:=c)

     elc-stamp: $(ELFILES)
             @rm -f elc-temp
             @touch elc-temp
             $(elisp_comp) $(ELFILES)
             @mv -f elc-temp $@

     $(ELCFILES): elc-stamp
     ## Recover from the removal of $@
             @dry=; for f in x $$MAKEFLAGS; do 
               case $$f in 
                 *=*|--*);; 
                 *n*) dry=:;; 
               esac; 
             done; 
             if test -f $@; then :; else 
               $$dry trap 'rm -rf elc-lock elc-stamp' 1 2 13 15; 
               if $$dry mkdir elc-lock 2>/dev/null; then 
     ## This code is being executed by the first process.
                 $$dry rm -f elc-stamp; 
                 $(MAKE) $(AM_MAKEFLAGS) elc-stamp; 
                 $$dry rmdir elc-lock; 
               else 
     ## This code is being executed by the follower processes.
     ## Wait until the first process is done.
                 while test -d elc-lock && test -z "$$dry"; do 
                   sleep 1; 
                 done; 
     ## Succeed if and only if the first process succeeded.
                 $$dry test -f elc-stamp; exit $$?; 
               fi; 
             fi

   For completeness it should be noted that GNU 'make' is able to
express rules with multiple output files using pattern rules (*note
Pattern Rule Examples: (make)Pattern Examples.).  We do not discuss
pattern rules here because they are not portable, but they can be
convenient in packages that assume GNU 'make'.

27.10 Installing to Hard-Coded Locations
========================================

     My package needs to install some configuration file.  I tried to use
     the following rule, but 'make distcheck' fails.  Why?

          # Do not do this.
          install-data-local:
                  $(INSTALL_DATA) $(srcdir)/afile $(DESTDIR)/etc/afile

     My package needs to populate the installation directory of another
     package at install-time.  I can easily compute that installation
     directory in 'configure', but if I install files therein,
     'make distcheck' fails.  How else should I do?

   These two setups share their symptoms: 'make distcheck' fails because
they are installing files to hard-coded paths.  In the later case the
path is not really hard-coded in the package, but we can consider it to
be hard-coded in the system (or in whichever tool that supplies the
path).  As long as the path does not use any of the standard directory
variables ('$(prefix)', '$(bindir)', '$(datadir)', etc.), the effect
will be the same: user-installations are impossible.

   As a (non-root) user who wants to install a package, you usually have
no right to install anything in '/usr' or '/usr/local'.  So you do
something like './configure --prefix ~/usr' to install a package in your
own '~/usr' tree.

   If a package attempts to install something to some hard-coded path
(e.g., '/etc/afile'), regardless of this '--prefix' setting, then the
installation will fail.  'make distcheck' performs such a '--prefix'
installation, hence it will fail too.

   Now, there are some easy solutions.

   The above 'install-data-local' example for installing '/etc/afile'
would be better replaced by

     sysconf_DATA = afile

by default 'sysconfdir' will be '$(prefix)/etc', because this is what
the GNU Standards require.  When such a package is installed on an FHS
compliant system, the installer will have to set '--sysconfdir=/etc'.
As the maintainer of the package you should not be concerned by such
site policies: use the appropriate standard directory variable to
install your files so that the installer can easily redefine these
variables to match their site conventions.

   Installing files that should be used by another package is slightly
more involved.  Let's take an example and assume you want to install a
shared library that is a Python extension module.  If you ask Python
where to install the library, it will answer something like this:

     % python -c 'from distutils import sysconfig;
                  print sysconfig.get_python_lib(1,0)'
     /usr/lib/python2.5/site-packages

   If you indeed use this absolute path to install your shared library,
non-root users will not be able to install the package, hence distcheck
fails.

   Let's do better.  The 'sysconfig.get_python_lib()' function actually
accepts a third argument that will replace Python's installation prefix.

     % python -c 'from distutils import sysconfig;
                  print sysconfig.get_python_lib(1,0,"${exec_prefix}")'
     ${exec_prefix}/lib/python2.5/site-packages

   You can also use this new path.  If you do
   * root users can install your package with the same '--prefix' as
     Python (you get the behavior of the previous attempt)

   * non-root users can install your package too, they will have the
     extension module in a place that is not searched by Python but they
     can work around this using environment variables (and if you
     installed scripts that use this shared library, it's easy to tell
     Python were to look in the beginning of your script, so the script
     works in both cases).

   The 'AM_PATH_PYTHON' macro uses similar commands to define
'$(pythondir)' and '$(pyexecdir)' (*note Python::).

   Of course not all tools are as advanced as Python regarding that
substitution of PREFIX.  So another strategy is to figure the part of
the installation directory that must be preserved.  For instance, here
is how 'AM_PATH_LISPDIR' (*note Emacs Lisp::) computes '$(lispdir)':

     $EMACS -batch -q -eval '(while load-path
       (princ (concat (car load-path) "n"))
       (setq load-path (cdr load-path)))' >conftest.out
     lispdir=`sed -n
       -e 's,/$,,'
       -e '/.*/lib/x*emacs/site-lisp$/{
             s,.*/lib/(x*emacs/site-lisp)$,${libdir}/1,;p;q;
           }'
       -e '/.*/share/x*emacs/site-lisp$/{
             s,.*/share/(x*emacs/site-lisp),${datarootdir}/1,;p;q;
           }'
       conftest.out`

   I.e., it just picks the first directory that looks like
'*/lib/*emacs/site-lisp' or '*/share/*emacs/site-lisp' in the search
path of emacs, and then substitutes '${libdir}' or '${datadir}'
appropriately.

   The emacs case looks complicated because it processes a list and
expects two possible layouts, otherwise it's easy, and the benefits for
non-root users are really worth the extra 'sed' invocation.

27.11 Debugging Make Rules
==========================

The rules and dependency trees generated by 'automake' can get rather
complex, and leave the developer head-scratching when things don't work
as expected.  Besides the debug options provided by the 'make' command
(*note (make)Options Summary::), here's a couple of further hints for
debugging makefiles generated by 'automake' effectively:

   * If less verbose output has been enabled in the package with the use
     of silent rules (*note Automake Silent Rules::), you can use 'make
     V=1' to see the commands being executed.
   * 'make -n' can help show what would be done without actually doing
     it.  Note however, that this will _still execute_ commands prefixed
     with '+', and, when using GNU 'make', commands that contain the
     strings '$(MAKE)' or '${MAKE}' (*note (make)Instead of
     Execution::).  Typically, this is helpful to show what recursive
     rules would do, but it means that, in your own rules, you should
     not mix such recursion with actions that change any files.(1)
     Furthermore, note that GNU 'make' will update prerequisites for the
     'Makefile' file itself even with '-n' (*note (make)Remaking
     Makefiles::).
   * 'make SHELL="/bin/bash -vx"' can help debug complex rules.  *Note
     (autoconf)The Make Macro SHELL::, for some portability quirks
     associated with this construct.
   * 'echo 'print: ; @echo "$(VAR)"' | make -f Makefile -f - print' can
     be handy to examine the expanded value of variables.  You may need
     to use a target other than 'print' if that is already used or a
     file with that name exists.
   * <http://bashdb.sourceforge.net/remake/> provides a modified GNU
     'make' command called 'remake' that copes with complex GNU
     'make'-specific Makefiles and allows to trace execution, examine
     variables, and call rules interactively, much like a debugger.

   ---------- Footnotes ----------

   (1) Automake's 'dist' and 'distcheck' rules had a bug in this regard
in that they created directories even with '-n', but this has been fixed
in Automake 1.11.

27.12 Reporting Bugs
====================

Most nontrivial software has bugs.  Automake is no exception.  Although
we cannot promise we can or will fix a bug, and we might not even agree
that it is a bug, we want to hear about problems you encounter.  Often
we agree they are bugs and want to fix them.

   To make it possible for us to fix a bug, please report it.  In order
to do so effectively, it helps to know when and how to do it.

   Before reporting a bug, it is a good idea to see if it is already
known.  You can look at the GNU Bug Tracker (http://debbugs.gnu.org/)
and the bug-automake mailing list archives
(http://lists.gnu.org/archive/html/bug-automake/) for previous bug
reports.  We previously used a Gnats database
(http://sourceware.org/cgi-bin/gnatsweb.pl?database=automake) for bug
tracking, so some bugs might have been reported there already.  Please
do not use it for new bug reports, however.

   If the bug is not already known, it should be reported.  It is very
important to report bugs in a way that is useful and efficient.  For
this, please familiarize yourself with How to Report Bugs Effectively
(http://www.chiark.greenend.org.uk/~sgtatham/bugs.html) and How to Ask
Questions the Smart Way
(http://catb.org/~esr/faqs/smart-questions.html).  This helps you and
developers to save time which can then be spent on fixing more bugs and
implementing more features.

   For a bug report, a feature request or other suggestions, please send
email to <bug-automake@gnu.org>.  This will then open a new bug in the
bug tracker (http://debbugs.gnu.org/automake).  Be sure to include the
versions of Autoconf and Automake that you use.  Ideally, post a minimal
'Makefile.am' and 'configure.ac' that reproduces the problem you
encounter.  If you have encountered test suite failures, please attach
the 'test-suite.log' file.

Appendix A Copying This Manual
******************************

A.1 GNU Free Documentation License
==================================

                     Version 1.3, 3 November 2008

     Copyright (C) 2000-2013 Free Software Foundation, Inc.
     <http://fsf.org/>

     Everyone is permitted to copy and distribute verbatim copies
     of this license document, but changing it is not allowed.

  0. PREAMBLE

     The purpose of this License is to make a manual, textbook, or other
     functional and useful document "free" in the sense of freedom: to
     assure everyone the effective freedom to copy and redistribute it,
     with or without modifying it, either commercially or
     noncommercially.  Secondarily, this License preserves for the
     author and publisher a way to get credit for their work, while not
     being considered responsible for modifications made by others.

     This License is a kind of "copyleft", which means that derivative
     works of the document must themselves be free in the same sense.
     It complements the GNU General Public License, which is a copyleft
     license designed for free software.

     We have designed this License in order to use it for manuals for
     free software, because free software needs free documentation: a
     free program should come with manuals providing the same freedoms
     that the software does.  But this License is not limited to
     software manuals; it can be used for any textual work, regardless
     of subject matter or whether it is published as a printed book.  We
     recommend this License principally for works whose purpose is
     instruction or reference.

  1. APPLICABILITY AND DEFINITIONS

     This License applies to any manual or other work, in any medium,
     that contains a notice placed by the copyright holder saying it can
     be distributed under the terms of this License.  Such a notice
     grants a world-wide, royalty-free license, unlimited in duration,
     to use that work under the conditions stated herein.  The
     "Document", below, refers to any such manual or work.  Any member
     of the public is a licensee, and is addressed as "you".  You accept
     the license if you copy, modify or distribute the work in a way
     requiring permission under copyright law.

     A "Modified Version" of the Document means any work containing the
     Document or a portion of it, either copied verbatim, or with
     modifications and/or translated into another language.

     A "Secondary Section" is a named appendix or a front-matter section
     of the Document that deals exclusively with the relationship of the
     publishers or authors of the Document to the Document's overall
     subject (or to related matters) and contains nothing that could
     fall directly within that overall subject.  (Thus, if the Document
     is in part a textbook of mathematics, a Secondary Section may not
     explain any mathematics.)  The relationship could be a matter of
     historical connection with the subject or with related matters, or
     of legal, commercial, philosophical, ethical or political position
     regarding them.

     The "Invariant Sections" are certain Secondary Sections whose
     titles are designated, as being those of Invariant Sections, in the
     notice that says that the Document is released under this License.
     If a section does not fit the above definition of Secondary then it
     is not allowed to be designated as Invariant.  The Document may
     contain zero Invariant Sections.  If the Document does not identify
     any Invariant Sections then there are none.

     The "Cover Texts" are certain short passages of text that are
     listed, as Front-Cover Texts or Back-Cover Texts, in the notice
     that says that the Document is released under this License.  A
     Front-Cover Text may be at most 5 words, and a Back-Cover Text may
     be at most 25 words.

     A "Transparent" copy of the Document means a machine-readable copy,
     represented in a format whose specification is available to the
     general public, that is suitable for revising the document
     straightforwardly with generic text editors or (for images composed
     of pixels) generic paint programs or (for drawings) some widely
     available drawing editor, and that is suitable for input to text
     formatters or for automatic translation to a variety of formats
     suitable for input to text formatters.  A copy made in an otherwise
     Transparent file format whose markup, or absence of markup, has
     been arranged to thwart or discourage subsequent modification by
     readers is not Transparent.  An image format is not Transparent if
     used for any substantial amount of text.  A copy that is not
     "Transparent" is called "Opaque".

     Examples of suitable formats for Transparent copies include plain
     ASCII without markup, Texinfo input format, LaTeX input format,
     SGML or XML using a publicly available DTD, and standard-conforming
     simple HTML, PostScript or PDF designed for human modification.
     Examples of transparent image formats include PNG, XCF and JPG.
     Opaque formats include proprietary formats that can be read and
     edited only by proprietary word processors, SGML or XML for which
     the DTD and/or processing tools are not generally available, and
     the machine-generated HTML, PostScript or PDF produced by some word
     processors for output purposes only.

     The "Title Page" means, for a printed book, the title page itself,
     plus such following pages as are needed to hold, legibly, the
     material this License requires to appear in the title page.  For
     works in formats which do not have any title page as such, "Title
     Page" means the text near the most prominent appearance of the
     work's title, preceding the beginning of the body of the text.

     The "publisher" means any person or entity that distributes copies
     of the Document to the public.

     A section "Entitled XYZ" means a named subunit of the Document
     whose title either is precisely XYZ or contains XYZ in parentheses
     following text that translates XYZ in another language.  (Here XYZ
     stands for a specific section name mentioned below, such as
     "Acknowledgements", "Dedications", "Endorsements", or "History".)
     To "Preserve the Title" of such a section when you modify the
     Document means that it remains a section "Entitled XYZ" according
     to this definition.

     The Document may include Warranty Disclaimers next to the notice
     which states that this License applies to the Document.  These
     Warranty Disclaimers are considered to be included by reference in
     this License, but only as regards disclaiming warranties: any other
     implication that these Warranty Disclaimers may have is void and
     has no effect on the meaning of this License.

  2. VERBATIM COPYING

     You may copy and distribute the Document in any medium, either
     commercially or noncommercially, provided that this License, the
     copyright notices, and the license notice saying this License
     applies to the Document are reproduced in all copies, and that you
     add no other conditions whatsoever to those of this License.  You
     may not use technical measures to obstruct or control the reading
     or further copying of the copies you make or distribute.  However,
     you may accept compensation in exchange for copies.  If you
     distribute a large enough number of copies you must also follow the
     conditions in section 3.

     You may also lend copies, under the same conditions stated above,
     and you may publicly display copies.

  3. COPYING IN QUANTITY

     If you publish printed copies (or copies in media that commonly
     have printed covers) of the Document, numbering more than 100, and
     the Document's license notice requires Cover Texts, you must
     enclose the copies in covers that carry, clearly and legibly, all
     of these Cover Texts: Front-Cover Texts on the front cover, and
     Back-Cover Texts on the back cover.  Both covers must also clearly
     and legibly identify you as the publisher of these copies.  The
     front cover must present the full title with all words of the title
     equally prominent and visible.  You may add other material on the
     covers in addition.  Copying with changes limited to the covers, as
     long as they preserve the title of the Document and satisfy these
     conditions, can be treated as verbatim copying in other respects.

     If the required texts for either cover are too voluminous to fit
     legibly, you should put the first ones listed (as many as fit
     reasonably) on the actual cover, and continue the rest onto
     adjacent pages.

     If you publish or distribute Opaque copies of the Document
     numbering more than 100, you must either include a machine-readable
     Transparent copy along with each Opaque copy, or state in or with
     each Opaque copy a computer-network location from which the general
     network-using public has access to download using public-standard
     network protocols a complete Transparent copy of the Document, free
     of added material.  If you use the latter option, you must take
     reasonably prudent steps, when you begin distribution of Opaque
     copies in quantity, to ensure that this Transparent copy will
     remain thus accessible at the stated location until at least one
     year after the last time you distribute an Opaque copy (directly or
     through your agents or retailers) of that edition to the public.

     It is requested, but not required, that you contact the authors of
     the Document well before redistributing any large number of copies,
     to give them a chance to provide you with an updated version of the
     Document.

  4. MODIFICATIONS

     You may copy and distribute a Modified Version of the Document
     under the conditions of sections 2 and 3 above, provided that you
     release the Modified Version under precisely this License, with the
     Modified Version filling the role of the Document, thus licensing
     distribution and modification of the Modified Version to whoever
     possesses a copy of it.  In addition, you must do these things in
     the Modified Version:

       A. Use in the Title Page (and on the covers, if any) a title
          distinct from that of the Document, and from those of previous
          versions (which should, if there were any, be listed in the
          History section of the Document).  You may use the same title
          as a previous version if the original publisher of that
          version gives permission.

       B. List on the Title Page, as authors, one or more persons or
          entities responsible for authorship of the modifications in
          the Modified Version, together with at least five of the
          principal authors of the Document (all of its principal
          authors, if it has fewer than five), unless they release you
          from this requirement.

       C. State on the Title page the name of the publisher of the
          Modified Version, as the publisher.

       D. Preserve all the copyright notices of the Document.

       E. Add an appropriate copyright notice for your modifications
          adjacent to the other copyright notices.

       F. Include, immediately after the copyright notices, a license
          notice giving the public permission to use the Modified
          Version under the terms of this License, in the form shown in
          the Addendum below.

       G. Preserve in that license notice the full lists of Invariant
          Sections and required Cover Texts given in the Document's
          license notice.

       H. Include an unaltered copy of this License.

       I. Preserve the section Entitled "History", Preserve its Title,
          and add to it an item stating at least the title, year, new
          authors, and publisher of the Modified Version as given on the
          Title Page.  If there is no section Entitled "History" in the
          Document, create one stating the title, year, authors, and
          publisher of the Document as given on its Title Page, then add
          an item describing the Modified Version as stated in the
          previous sentence.

       J. Preserve the network location, if any, given in the Document
          for public access to a Transparent copy of the Document, and
          likewise the network locations given in the Document for
          previous versions it was based on.  These may be placed in the
          "History" section.  You may omit a network location for a work
          that was published at least four years before the Document
          itself, or if the original publisher of the version it refers
          to gives permission.

       K. For any section Entitled "Acknowledgements" or "Dedications",
          Preserve the Title of the section, and preserve in the section
          all the substance and tone of each of the contributor
          acknowledgements and/or dedications given therein.

       L. Preserve all the Invariant Sections of the Document, unaltered
          in their text and in their titles.  Section numbers or the
          equivalent are not considered part of the section titles.

       M. Delete any section Entitled "Endorsements".  Such a section
          may not be included in the Modified Version.

       N. Do not retitle any existing section to be Entitled
          "Endorsements" or to conflict in title with any Invariant
          Section.

       O. Preserve any Warranty Disclaimers.

     If the Modified Version includes new front-matter sections or
     appendices that qualify as Secondary Sections and contain no
     material copied from the Document, you may at your option designate
     some or all of these sections as invariant.  To do this, add their
     titles to the list of Invariant Sections in the Modified Version's
     license notice.  These titles must be distinct from any other
     section titles.

     You may add a section Entitled "Endorsements", provided it contains
     nothing but endorsements of your Modified Version by various
     parties--for example, statements of peer review or that the text
     has been approved by an organization as the authoritative
     definition of a standard.

     You may add a passage of up to five words as a Front-Cover Text,
     and a passage of up to 25 words as a Back-Cover Text, to the end of
     the list of Cover Texts in the Modified Version.  Only one passage
     of Front-Cover Text and one of Back-Cover Text may be added by (or
     through arrangements made by) any one entity.  If the Document
     already includes a cover text for the same cover, previously added
     by you or by arrangement made by the same entity you are acting on
     behalf of, you may not add another; but you may replace the old
     one, on explicit permission from the previous publisher that added
     the old one.

     The author(s) and publisher(s) of the Document do not by this
     License give permission to use their names for publicity for or to
     assert or imply endorsement of any Modified Version.

  5. COMBINING DOCUMENTS

     You may combine the Document with other documents released under
     this License, under the terms defined in section 4 above for
     modified versions, provided that you include in the combination all
     of the Invariant Sections of all of the original documents,
     unmodified, and list them all as Invariant Sections of your
     combined work in its license notice, and that you preserve all
     their Warranty Disclaimers.

     The combined work need only contain one copy of this License, and
     multiple identical Invariant Sections may be replaced with a single
     copy.  If there are multiple Invariant Sections with the same name
     but different contents, make the title of each such section unique
     by adding at the end of it, in parentheses, the name of the
     original author or publisher of that section if known, or else a
     unique number.  Make the same adjustment to the section titles in
     the list of Invariant Sections in the license notice of the
     combined work.

     In the combination, you must combine any sections Entitled
     "History" in the various original documents, forming one section
     Entitled "History"; likewise combine any sections Entitled
     "Acknowledgements", and any sections Entitled "Dedications".  You
     must delete all sections Entitled "Endorsements."

  6. COLLECTIONS OF DOCUMENTS

     You may make a collection consisting of the Document and other
     documents released under this License, and replace the individual
     copies of this License in the various documents with a single copy
     that is included in the collection, provided that you follow the
     rules of this License for verbatim copying of each of the documents
     in all other respects.

     You may extract a single document from such a collection, and
     distribute it individually under this License, provided you insert
     a copy of this License into the extracted document, and follow this
     License in all other respects regarding verbatim copying of that
     document.

  7. AGGREGATION WITH INDEPENDENT WORKS

     A compilation of the Document or its derivatives with other
     separate and independent documents or works, in or on a volume of a
     storage or distribution medium, is called an "aggregate" if the
     copyright resulting from the compilation is not used to limit the
     legal rights of the compilation's users beyond what the individual
     works permit.  When the Document is included in an aggregate, this
     License does not apply to the other works in the aggregate which
     are not themselves derivative works of the Document.

     If the Cover Text requirement of section 3 is applicable to these
     copies of the Document, then if the Document is less than one half
     of the entire aggregate, the Document's Cover Texts may be placed
     on covers that bracket the Document within the aggregate, or the
     electronic equivalent of covers if the Document is in electronic
     form.  Otherwise they must appear on printed covers that bracket
     the whole aggregate.

  8. TRANSLATION

     Translation is considered a kind of modification, so you may
     distribute translations of the Document under the terms of section
     4.  Replacing Invariant Sections with translations requires special
     permission from their copyright holders, but you may include
     translations of some or all Invariant Sections in addition to the
     original versions of these Invariant Sections.  You may include a
     translation of this License, and all the license notices in the
     Document, and any Warranty Disclaimers, provided that you also
     include the original English version of this License and the
     original versions of those notices and disclaimers.  In case of a
     disagreement between the translation and the original version of
     this License or a notice or disclaimer, the original version will
     prevail.

     If a section in the Document is Entitled "Acknowledgements",
     "Dedications", or "History", the requirement (section 4) to
     Preserve its Title (section 1) will typically require changing the
     actual title.

  9. TERMINATION

     You may not copy, modify, sublicense, or distribute the Document
     except as expressly provided under this License.  Any attempt
     otherwise to copy, modify, sublicense, or distribute it is void,
     and will automatically terminate your rights under this License.

     However, if you cease all violation of this License, then your
     license from a particular copyright holder is reinstated (a)
     provisionally, unless and until the copyright holder explicitly and
     finally terminates your license, and (b) permanently, if the
     copyright holder fails to notify you of the violation by some
     reasonable means prior to 60 days after the cessation.

     Moreover, your license from a particular copyright holder is
     reinstated permanently if the copyright holder notifies you of the
     violation by some reasonable means, this is the first time you have
     received notice of violation of this License (for any work) from
     that copyright holder, and you cure the violation prior to 30 days
     after your receipt of the notice.

     Termination of your rights under this section does not terminate
     the licenses of parties who have received copies or rights from you
     under this License.  If your rights have been terminated and not
     permanently reinstated, receipt of a copy of some or all of the
     same material does not give you any rights to use it.

  10. FUTURE REVISIONS OF THIS LICENSE

     The Free Software Foundation may publish new, revised versions of
     the GNU Free Documentation License from time to time.  Such new
     versions will be similar in spirit to the present version, but may
     differ in detail to address new problems or concerns.  See
     <http://www.gnu.org/copyleft/>.

     Each version of the License is given a distinguishing version
     number.  If the Document specifies that a particular numbered
     version of this License "or any later version" applies to it, you
     have the option of following the terms and conditions either of
     that specified version or of any later version that has been
     published (not as a draft) by the Free Software Foundation.  If the
     Document does not specify a version number of this License, you may
     choose any version ever published (not as a draft) by the Free
     Software Foundation.  If the Document specifies that a proxy can
     decide which future versions of this License can be used, that
     proxy's public statement of acceptance of a version permanently
     authorizes you to choose that version for the Document.

  11. RELICENSING

     "Massive Multiauthor Collaboration Site" (or "MMC Site") means any
     World Wide Web server that publishes copyrightable works and also
     provides prominent facilities for anybody to edit those works.  A
     public wiki that anybody can edit is an example of such a server.
     A "Massive Multiauthor Collaboration" (or "MMC") contained in the
     site means any set of copyrightable works thus published on the MMC
     site.

     "CC-BY-SA" means the Creative Commons Attribution-Share Alike 3.0
     license published by Creative Commons Corporation, a not-for-profit
     corporation with a principal place of business in San Francisco,
     California, as well as future copyleft versions of that license
     published by that same organization.

     "Incorporate" means to publish or republish a Document, in whole or
     in part, as part of another Document.

     An MMC is "eligible for relicensing" if it is licensed under this
     License, and if all works that were first published under this
     License somewhere other than this MMC, and subsequently
     incorporated in whole or in part into the MMC, (1) had no cover
     texts or invariant sections, and (2) were thus incorporated prior
     to November 1, 2008.

     The operator of an MMC Site may republish an MMC contained in the
     site under CC-BY-SA on the same site at any time before August 1,
     2009, provided the MMC is eligible for relicensing.

ADDENDUM: How to use this License for your documents
====================================================

To use this License in a document you have written, include a copy of
the License in the document and put the following copyright and license
notices just after the title page:

       Copyright (C)  YEAR  YOUR NAME.
       Permission is granted to copy, distribute and/or modify this document
       under the terms of the GNU Free Documentation License, Version 1.3
       or any later version published by the Free Software Foundation;
       with no Invariant Sections, no Front-Cover Texts, and no Back-Cover
       Texts.  A copy of the license is included in the section entitled ``GNU
       Free Documentation License''.

   If you have Invariant Sections, Front-Cover Texts and Back-Cover
Texts, replace the "with...Texts."  line with this:

         with the Invariant Sections being LIST THEIR TITLES, with
         the Front-Cover Texts being LIST, and with the Back-Cover Texts
         being LIST.

   If you have Invariant Sections without Cover Texts, or some other
combination of the three, merge those two alternatives to suit the
situation.

   If your document contains nontrivial examples of program code, we
recommend releasing these examples in parallel under your choice of free
software license, such as the GNU General Public License, to permit
their use in free software.

Appendix B Indices
******************

B.1 Macro Index
===============

* Menu:

* _AM_DEPENDENCIES:                      Private Macros.     (line 3058)
* AC_CANONICAL_BUILD:                    Optional.           (line 2118)
* AC_CANONICAL_HOST:                     Optional.           (line 2119)
* AC_CANONICAL_TARGET:                   Optional.           (line 2120)
* AC_CONFIG_AUX_DIR:                     Optional.           (line 2126)
* AC_CONFIG_AUX_DIR <1>:                 Subpackages.        (line 3414)
* AC_CONFIG_FILES:                       Requirements.       (line 2005)
* AC_CONFIG_HEADERS:                     Optional.           (line 2151)
* AC_CONFIG_LIBOBJ_DIR:                  Optional.           (line 2147)
* AC_CONFIG_LIBOBJ_DIR <1>:              LIBOBJS.            (line 4530)
* AC_CONFIG_LINKS:                       Optional.           (line 2162)
* AC_CONFIG_SUBDIRS:                     Subpackages.        (line 3414)
* AC_DEFUN:                              Extending aclocal.  (line 2621)
* AC_F77_LIBRARY_LDFLAGS:                Optional.           (line 2208)
* AC_FC_SRCEXT:                          Optional.           (line 2214)
* AC_INIT:                               Public Macros.      (line 2914)
* AC_LIBOBJ:                             Optional.           (line 2172)
* AC_LIBOBJ <1>:                         LTLIBOBJS.          (line 4122)
* AC_LIBOBJ <2>:                         LIBOBJS.            (line 4490)
* AC_LIBSOURCE:                          Optional.           (line 2173)
* AC_LIBSOURCE <1>:                      LIBOBJS.            (line 4496)
* AC_LIBSOURCES:                         Optional.           (line 2174)
* AC_OUTPUT:                             Requirements.       (line 2005)
* AC_PREREQ:                             Extending aclocal.  (line 2621)
* AC_PROG_CXX:                           Optional.           (line 2192)
* AC_PROG_F77:                           Optional.           (line 2204)
* AC_PROG_FC:                            Optional.           (line 2219)
* AC_PROG_LEX:                           Public Macros.      (line 2991)
* AC_PROG_LEX <1>:                       Optional.           (line 2234)
* AC_PROG_LIBTOOL:                       Optional.           (line 2224)
* AC_PROG_OBJC:                          Optional.           (line 2196)
* AC_PROG_OBJCXX:                        Optional.           (line 2200)
* AC_PROG_RANLIB:                        Optional.           (line 2188)
* AC_PROG_YACC:                          Optional.           (line 2228)
* AC_REQUIRE_AUX_FILE:                   Optional.           (line 2238)
* AC_SUBST:                              Optional.           (line 2246)
* AM_CONDITIONAL:                        Optional.           (line 2259)
* AM_CONDITIONAL <1>:                    Usage of Conditionals.
                                                             (line 8037)
* AM_CONDITIONAL <2>:                    Usage of Conditionals.
                                                             (line 8040)
* AM_COND_IF:                            Optional.           (line 2262)
* AM_COND_IF <1>:                        Usage of Conditionals.
                                                             (line 8097)
* AM_COND_IF <2>:                        Usage of Conditionals.
                                                             (line 8101)
* AM_DEP_TRACK:                          Private Macros.     (line 3060)
* AM_GNU_GETTEXT:                        Optional.           (line 2268)
* AM_GNU_GETTEXT_INTL_SUBDIR:            Optional.           (line 2274)
* AM_INIT_AUTOMAKE:                      Requirements.       (line 1996)
* AM_INIT_AUTOMAKE <1>:                  Public Macros.      (line 2906)
* AM_MAINTAINER_MODE:                    Rebuilding.         (line 7549)
* AM_MAINTAINER_MODE <1>:                maintainer-mode.    (line 9037)
* AM_MAINTAINER_MODE([DEFAULT-MODE]):    Optional.           (line 2279)
* AM_MAKE_INCLUDE:                       Private Macros.     (line 3066)
* AM_MISSING_PROG:                       Public Macros.      (line 3007)
* AM_OUTPUT_DEPENDENCY_COMMANDS:         Private Macros.     (line 3061)
* AM_PATH_LISPDIR:                       Public Macros.      (line 2957)
* AM_PATH_PYTHON:                        Python.             (line 5842)
* AM_PROG_AR:                            Public Macros.      (line 2972)
* AM_PROG_AS:                            Public Macros.      (line 2979)
* AM_PROG_CC_C_O:                        Public Macros.      (line 2984)
* AM_PROG_GCJ:                           Public Macros.      (line 2996)
* AM_PROG_INSTALL_STRIP:                 Private Macros.     (line 3071)
* AM_PROG_LEX:                           Public Macros.      (line 2991)
* AM_PROG_MKDIR_P:                       Obsolete Macros.    (line 3034)
* AM_PROG_UPC:                           Public Macros.      (line 3001)
* AM_PROG_VALAC:                         Vala Support.       (line 5198)
* AM_SANITY_CHECK:                       Private Macros.     (line 3076)
* AM_SET_DEPDIR:                         Private Macros.     (line 3059)
* AM_SILENT_RULES:                       Public Macros.      (line 3015)
* AM_SUBST_NOTMAKE(VAR):                 Optional.           (line 2287)
* AM_WITH_DMALLOC:                       Public Macros.      (line 3019)
* m4_include:                            Basics of Distribution.
                                                             (line 6345)
* m4_include <1>:                        Optional.           (line 2297)

B.2 Variable Index
==================

* Menu:

* _DATA:                                 Data.               (line 5447)
* _HEADERS:                              Headers.            (line 5407)
* _LIBRARIES:                            A Library.          (line 3751)
* _LISP:                                 Emacs Lisp.         (line 5702)
* _LOG_COMPILE:                          Parallel Test Harness.
                                                             (line 6913)
* _LOG_COMPILER:                         Parallel Test Harness.
                                                             (line 6913)
* _LOG_DRIVER:                           Declaring Custom Test Drivers.
                                                             (line 7101)
* _LOG_DRIVER_FLAGS:                     Declaring Custom Test Drivers.
                                                             (line 7101)
* _LOG_FLAGS:                            Parallel Test Harness.
                                                             (line 6913)
* _LTLIBRARIES:                          Libtool Libraries.  (line 3855)
* _MANS:                                 Man Pages.          (line 6092)
* _PROGRAMS:                             Uniform.            (line 1404)
* _PROGRAMS <1>:                         Program Sources.    (line 3515)
* _PYTHON:                               Python.             (line 5820)
* _SCRIPTS:                              Scripts.            (line 5336)
* _SOURCES:                              Program Sources.    (line 3541)
* _SOURCES <1>:                          Program Sources.    (line 3542)
* _SOURCES <2>:                          Default _SOURCES.   (line 4432)
* _TEXINFOS:                             Texinfo.            (line 5940)
* _TEXINFOS <1>:                         Texinfo.            (line 5999)
* ALLOCA:                                LTLIBOBJS.          (line 4122)
* ALLOCA <1>:                            LIBOBJS.            (line 4485)
* AM_CCASFLAGS:                          Assembly Support.   (line 4920)
* AM_CFLAGS:                             Program Variables.  (line 4644)
* AM_COLOR_TESTS:                        Scripts-based Testsuites.
                                                             (line 6753)
* AM_CPPFLAGS:                           Program Variables.  (line 4610)
* AM_CPPFLAGS <1>:                       Assembly Support.   (line 4920)
* AM_CXXFLAGS:                           C++ Support.        (line 4817)
* AM_DEFAULT_SOURCE_EXT:                 Default _SOURCES.   (line 4432)
* 'AM_DEFAULT_V':                        Automake Silent Rules.
                                                             (line 8353)
* 'AM_DEFAULT_VERBOSITY':                Automake Silent Rules.
                                                             (line 8353)
* AM_DISTCHECK_CONFIGURE_FLAGS:          Checking the Distribution.
                                                             (line 6468)
* AM_ETAGSFLAGS:                         Tags.               (line 7901)
* AM_EXT_LOG_DRIVER_FLAGS:               Declaring Custom Test Drivers.
                                                             (line 7101)
* AM_EXT_LOG_FLAGS:                      Parallel Test Harness.
                                                             (line 6913)
* AM_FCFLAGS:                            Fortran 9x Support. (line 5121)
* AM_FFLAGS:                             Fortran 77 Support. (line 4954)
* AM_GCJFLAGS:                           Java Support with gcj.
                                                             (line 5174)
* AM_INSTALLCHECK_STD_OPTIONS_EXEMPT:    List of Automake options.
                                                             (line 7787)
* AM_JAVACFLAGS:                         Java.               (line 5803)
* AM_LDFLAGS:                            Linking.            (line 3561)
* AM_LDFLAGS <1>:                        Program Variables.  (line 4653)
* AM_LFLAGS:                             Yacc and Lex.       (line 4723)
* AM_LIBTOOLFLAGS:                       Libtool Flags.      (line 4086)
* AM_LOG_DRIVER_FLAGS:                   Declaring Custom Test Drivers.
                                                             (line 7101)
* AM_LOG_FLAGS:                          Parallel Test Harness.
                                                             (line 6913)
* AM_MAKEFLAGS:                          Subdirectories.     (line 3134)
* AM_MAKEINFOFLAGS:                      Texinfo.            (line 6049)
* AM_MAKEINFOHTMLFLAGS:                  Texinfo.            (line 6050)
* AM_OBJCFLAGS:                          Objective C Support.
                                                             (line 4846)
* AM_OBJCXXFLAGS:                        Objective C++ Support.
                                                             (line 4875)
* AM_RFLAGS:                             Fortran 77 Support. (line 4960)
* AM_RUNTESTFLAGS:                       DejaGnu Tests.      (line 7516)
* AM_TESTS_ENVIRONMENT:                  Scripts-based Testsuites.
                                                             (line 6772)
* AM_TESTS_FD_REDIRECT:                  Scripts-based Testsuites.
                                                             (line 6780)
* AM_UPCFLAGS:                           Unified Parallel C Support.
                                                             (line 4903)
* AM_UPDATE_INFO_DIR:                    Texinfo.            (line 6026)
* 'AM_V':                                Automake Silent Rules.
                                                             (line 8353)
* AM_VALAFLAGS:                          Vala Support.       (line 5219)
* 'AM_V_at':                             Automake Silent Rules.
                                                             (line 8353)
* 'AM_V_GEN':                            Automake Silent Rules.
                                                             (line 8353)
* AM_YFLAGS:                             Yacc and Lex.       (line 4700)
* AR:                                    Public Macros.      (line 2972)
* AUTOCONF:                              automake Invocation.
                                                             (line 1830)
* AUTOM4TE:                              aclocal Invocation. (line 2348)
* AUTOMAKE_JOBS:                         automake Invocation.
                                                             (line 1976)
* AUTOMAKE_OPTIONS:                      Public Macros.      (line 2909)
* AUTOMAKE_OPTIONS <1>:                  Dependencies.       (line 5273)
* AUTOMAKE_OPTIONS <2>:                  List of Automake options.
                                                             (line 7661)
* bin_PROGRAMS:                          Program Sources.    (line 3515)
* bin_SCRIPTS:                           Scripts.            (line 5348)
* build_triplet:                         Optional.           (line 2121)
* BUILT_SOURCES:                         Sources.            (line 5485)
* BZIP2:                                 The Types of Distributions.
                                                             (line 6577)
* CC:                                    Program Variables.  (line 4606)
* CCAS:                                  Public Macros.      (line 2979)
* CCAS <1>:                              Assembly Support.   (line 4920)
* CCASFLAGS:                             Public Macros.      (line 2979)
* CCASFLAGS <1>:                         Assembly Support.   (line 4920)
* CFLAGS:                                Program Variables.  (line 4606)
* check_:                                Uniform.            (line 1489)
* check_LTLIBRARIES:                     Libtool Convenience Libraries.
                                                             (line 3980)
* check_PROGRAMS:                        Program Sources.    (line 3515)
* check_PROGRAMS <1>:                    Default _SOURCES.   (line 4454)
* check_SCRIPTS:                         Scripts.            (line 5348)
* CLASSPATH_ENV:                         Java.               (line 5812)
* CLEANFILES:                            Clean.              (line 6291)
* COMPILE:                               Program Variables.  (line 4649)
* CONFIGURE_DEPENDENCIES:                Rebuilding.         (line 7552)
* CONFIG_STATUS_DEPENDENCIES:            Rebuilding.         (line 7552)
* CPPFLAGS:                              Program Variables.  (line 4606)
* CPPFLAGS <1>:                          Assembly Support.   (line 4920)
* CXX:                                   C++ Support.        (line 4811)
* CXXCOMPILE:                            C++ Support.        (line 4820)
* CXXFLAGS:                              C++ Support.        (line 4814)
* CXXLINK:                               C++ Support.        (line 4824)
* CXXLINK <1>:                           How the Linker is Chosen.
                                                             (line 5078)
* DATA:                                  Uniform.            (line 1495)
* DATA <1>:                              Data.               (line 5448)
* data_DATA:                             Data.               (line 5450)
* DEFS:                                  Program Variables.  (line 4606)
* DEJATOOL:                              DejaGnu Tests.      (line 7511)
* DESTDIR:                               DESTDIR.            (line  789)
* DESTDIR <1>:                           Staged Installs.    (line 6242)
* DISABLE_HARD_ERRORS:                   Scripts-based Testsuites.
                                                             (line 6718)
* DISTCHECK_CONFIGURE_FLAGS:             Checking the Distribution.
                                                             (line 6468)
* distcleancheck_listfiles:              Checking the Distribution.
                                                             (line 6510)
* distcleancheck_listfiles <1>:          Errors with distclean.
                                                             (line 9312)
* DISTCLEANFILES:                        Clean.              (line 6291)
* DISTCLEANFILES <1>:                    Checking the Distribution.
                                                             (line 6510)
* distdir:                               The dist Hook.      (line 6431)
* distdir <1>:                           Third-Party Makefiles.
                                                             (line 8565)
* distuninstallcheck_listfiles:          Checking the Distribution.
                                                             (line 6546)
* dist_:                                 Alternative.        (line 3383)
* dist_ <1>:                             Fine-grained Distribution Control.
                                                             (line 6386)
* dist_lisp_LISP:                        Emacs Lisp.         (line 5707)
* dist_noinst_LISP:                      Emacs Lisp.         (line 5707)
* DIST_SUBDIRS:                          Subdirectories with AM_CONDITIONAL.
                                                             (line 3263)
* DIST_SUBDIRS <1>:                      Basics of Distribution.
                                                             (line 6375)
* DVIPS:                                 Texinfo.            (line 6075)
* EMACS:                                 Public Macros.      (line 2957)
* ETAGSFLAGS:                            Tags.               (line 7901)
* ETAGS_ARGS:                            Tags.               (line 7901)
* EXPECT:                                DejaGnu Tests.      (line 7511)
* EXTRA_DIST:                            Basics of Distribution.
                                                             (line 6362)
* EXTRA_maude_DEPENDENCIES:              Linking.            (line 3592)
* EXTRA_maude_DEPENDENCIES <1>:          Program and Library Variables.
                                                             (line 4315)
* EXTRA_maude_SOURCES:                   Program and Library Variables.
                                                             (line 4249)
* EXTRA_PROGRAMS:                        Conditional Programs.
                                                             (line 3716)
* EXT_LOG_COMPILE:                       Parallel Test Harness.
                                                             (line 6913)
* EXT_LOG_COMPILER:                      Parallel Test Harness.
                                                             (line 6913)
* EXT_LOG_DRIVER:                        Declaring Custom Test Drivers.
                                                             (line 7101)
* EXT_LOG_DRIVER_FLAGS:                  Declaring Custom Test Drivers.
                                                             (line 7101)
* EXT_LOG_FLAGS:                         Parallel Test Harness.
                                                             (line 6913)
* F77:                                   Fortran 77 Support. (line 4948)
* F77COMPILE:                            Fortran 77 Support. (line 4963)
* F77LINK:                               How the Linker is Chosen.
                                                             (line 5079)
* FC:                                    Fortran 9x Support. (line 5115)
* FCCOMPILE:                             Fortran 9x Support. (line 5124)
* FCFLAGS:                               Fortran 9x Support. (line 5118)
* FCLINK:                                How the Linker is Chosen.
                                                             (line 5080)
* FCLINK <1>:                            Fortran 9x Support. (line 5128)
* FFLAGS:                                Fortran 77 Support. (line 4951)
* FLIBS:                                 Mixing Fortran 77 With C and C++.
                                                             (line 5033)
* FLINK:                                 Fortran 77 Support. (line 4967)
* GCJ:                                   Public Macros.      (line 2996)
* GCJFLAGS:                              Public Macros.      (line 2996)
* GCJFLAGS <1>:                          Java Support with gcj.
                                                             (line 5164)
* GCJLINK:                               How the Linker is Chosen.
                                                             (line 5076)
* GTAGS_ARGS:                            Tags.               (line 7936)
* GZIP_ENV:                              Basics of Distribution.
                                                             (line 6342)
* HEADERS:                               Uniform.            (line 1495)
* host_triplet:                          Optional.           (line 2121)
* INCLUDES:                              Program Variables.  (line 4638)
* include_HEADERS:                       Headers.            (line 5407)
* info_TEXINFOS:                         Texinfo.            (line 5940)
* JAVA:                                  Uniform.            (line 1495)
* JAVAC:                                 Java.               (line 5796)
* JAVACFLAGS:                            Java.               (line 5799)
* JAVAROOT:                              Java.               (line 5808)
* LDADD:                                 Linking.            (line 3561)
* LDFLAGS:                               Program Variables.  (line 4606)
* LFLAGS:                                Yacc and Lex.       (line 4723)
* libexec_PROGRAMS:                      Program Sources.    (line 3515)
* libexec_SCRIPTS:                       Scripts.            (line 5348)
* LIBOBJS:                               Optional.           (line 2175)
* LIBOBJS <1>:                           LTLIBOBJS.          (line 4122)
* LIBOBJS <2>:                           LIBOBJS.            (line 4485)
* LIBRARIES:                             Uniform.            (line 1495)
* LIBS:                                  Program Variables.  (line 4606)
* LIBTOOLFLAGS:                          Libtool Flags.      (line 4086)
* lib_LIBRARIES:                         A Library.          (line 3751)
* lib_LTLIBRARIES:                       Libtool Libraries.  (line 3855)
* LINK:                                  Program Variables.  (line 4658)
* LINK <1>:                              How the Linker is Chosen.
                                                             (line 5083)
* LISP:                                  Uniform.            (line 1495)
* lispdir:                               Public Macros.      (line 2957)
* lisp_LISP:                             Emacs Lisp.         (line 5702)
* localstate_DATA:                       Data.               (line 5450)
* LOG_COMPILE:                           Parallel Test Harness.
                                                             (line 6913)
* LOG_COMPILER:                          Parallel Test Harness.
                                                             (line 6913)
* LOG_DRIVER:                            Declaring Custom Test Drivers.
                                                             (line 7101)
* LOG_DRIVER_FLAGS:                      Declaring Custom Test Drivers.
                                                             (line 7101)
* LOG_FLAGS:                             Parallel Test Harness.
                                                             (line 6913)
* LTALLOCA:                              LTLIBOBJS.          (line 4122)
* LTALLOCA <1>:                          LIBOBJS.            (line 4485)
* LTLIBOBJS:                             LTLIBOBJS.          (line 4122)
* LTLIBOBJS <1>:                         LIBOBJS.            (line 4485)
* LTLIBRARIES:                           Uniform.            (line 1495)
* MAINTAINERCLEANFILES:                  Clean.              (line 6291)
* MAKE:                                  Subdirectories.     (line 3134)
* MAKEINFO:                              Texinfo.            (line 6033)
* MAKEINFOFLAGS:                         Texinfo.            (line 6043)
* MAKEINFOHTML:                          Texinfo.            (line 6039)
* MANS:                                  Uniform.            (line 1495)
* man_MANS:                              Man Pages.          (line 6092)
* maude_AR:                              Program and Library Variables.
                                                             (line 4264)
* maude_CCASFLAGS:                       Program and Library Variables.
                                                             (line 4366)
* maude_CFLAGS:                          Program and Library Variables.
                                                             (line 4367)
* maude_CPPFLAGS:                        Program and Library Variables.
                                                             (line 4368)
* maude_CXXFLAGS:                        Program and Library Variables.
                                                             (line 4369)
* maude_DEPENDENCIES:                    Linking.            (line 3592)
* maude_DEPENDENCIES <1>:                Program and Library Variables.
                                                             (line 4314)
* maude_FFLAGS:                          Program and Library Variables.
                                                             (line 4370)
* maude_GCJFLAGS:                        Program and Library Variables.
                                                             (line 4371)
* maude_LDADD:                           Linking.            (line 3568)
* maude_LDADD <1>:                       Program and Library Variables.
                                                             (line 4282)
* maude_LDFLAGS:                         Linking.            (line 3588)
* maude_LDFLAGS <1>:                     Program and Library Variables.
                                                             (line 4302)
* maude_LFLAGS:                          Program and Library Variables.
                                                             (line 4372)
* maude_LIBADD:                          A Library.          (line 3771)
* maude_LIBADD <1>:                      Program and Library Variables.
                                                             (line 4274)
* maude_LIBTOOLFLAGS:                    Libtool Flags.      (line 4086)
* maude_LIBTOOLFLAGS <1>:                Program and Library Variables.
                                                             (line 4307)
* maude_LINK:                            Program and Library Variables.
                                                             (line 4350)
* maude_OBJCFLAGS:                       Program and Library Variables.
                                                             (line 4373)
* maude_OBJCXXFLAGS:                     Program and Library Variables.
                                                             (line 4374)
* maude_RFLAGS:                          Program and Library Variables.
                                                             (line 4375)
* maude_SHORTNAME:                       Program and Library Variables.
                                                             (line 4406)
* maude_SOURCES:                         Program and Library Variables.
                                                             (line 4214)
* maude_UPCFLAGS:                        Program and Library Variables.
                                                             (line 4376)
* maude_YFLAGS:                          Program and Library Variables.
                                                             (line 4377)
* MISSING:                               Public Macros.      (line 3007)
* MKDIR_P:                               Obsolete Macros.    (line 3034)
* mkdir_p:                               Obsolete Macros.    (line 3034)
* MOSTLYCLEANFILES:                      Clean.              (line 6291)
* nobase_:                               Alternative.        (line 3377)
* nodist_:                               Alternative.        (line 3383)
* nodist_ <1>:                           Fine-grained Distribution Control.
                                                             (line 6386)
* noinst_:                               Uniform.            (line 1484)
* noinst_HEADERS:                        Headers.            (line 5407)
* noinst_HEADERS <1>:                    Headers.            (line 5424)
* noinst_LIBRARIES:                      A Library.          (line 3751)
* noinst_LISP:                           Emacs Lisp.         (line 5702)
* noinst_LTLIBRARIES:                    Libtool Convenience Libraries.
                                                             (line 3980)
* noinst_PROGRAMS:                       Program Sources.    (line 3515)
* noinst_SCRIPTS:                        Scripts.            (line 5348)
* notrans_:                              Man Pages.          (line 6140)
* OBJC:                                  Objective C Support.
                                                             (line 4840)
* OBJCCOMPILE:                           Objective C Support.
                                                             (line 4849)
* OBJCFLAGS:                             Objective C Support.
                                                             (line 4843)
* OBJCLINK:                              Objective C Support.
                                                             (line 4853)
* OBJCLINK <1>:                          How the Linker is Chosen.
                                                             (line 5081)
* OBJCXX:                                Objective C++ Support.
                                                             (line 4869)
* OBJCXXCOMPILE:                         Objective C++ Support.
                                                             (line 4878)
* OBJCXXFLAGS:                           Objective C++ Support.
                                                             (line 4872)
* OBJCXXLINK:                            Objective C++ Support.
                                                             (line 4882)
* OBJCXXLINK <1>:                        How the Linker is Chosen.
                                                             (line 5077)
* oldinclude_HEADERS:                    Headers.            (line 5407)
* PACKAGE:                               Basics of Distribution.
                                                             (line 6338)
* pkgdatadir:                            Uniform.            (line 1412)
* pkgdata_DATA:                          Data.               (line 5450)
* pkgdata_SCRIPTS:                       Scripts.            (line 5348)
* pkgincludedir:                         Uniform.            (line 1412)
* pkginclude_HEADERS:                    Headers.            (line 5407)
* pkglibdir:                             Uniform.            (line 1412)
* pkglibexecdir:                         Uniform.            (line 1412)
* pkglibexec_PROGRAMS:                   Program Sources.    (line 3515)
* pkglibexec_SCRIPTS:                    Scripts.            (line 5348)
* pkglib_LIBRARIES:                      A Library.          (line 3751)
* pkglib_LTLIBRARIES:                    Libtool Libraries.  (line 3855)
* pkgpyexecdir:                          Python.             (line 5919)
* pkgpythondir:                          Python.             (line 5905)
* PROGRAMS:                              Uniform.            (line 1410)
* PROGRAMS <1>:                          Uniform.            (line 1495)
* pyexecdir:                             Python.             (line 5910)
* PYTHON:                                Uniform.            (line 1495)
* PYTHON <1>:                            Python.             (line 5870)
* pythondir:                             Python.             (line 5901)
* PYTHON_EXEC_PREFIX:                    Python.             (line 5891)
* PYTHON_PLATFORM:                       Python.             (line 5896)
* PYTHON_PREFIX:                         Python.             (line 5886)
* PYTHON_VERSION:                        Python.             (line 5882)
* RECHECK_LOGS:                          Parallel Test Harness.
                                                             (line 6980)
* RFLAGS:                                Fortran 77 Support. (line 4957)
* RUNTEST:                               DejaGnu Tests.      (line 7511)
* RUNTESTDEFAULTFLAGS:                   DejaGnu Tests.      (line 7506)
* RUNTESTFLAGS:                          DejaGnu Tests.      (line 7516)
* sbin_PROGRAMS:                         Program Sources.    (line 3515)
* sbin_SCRIPTS:                          Scripts.            (line 5348)
* SCRIPTS:                               Uniform.            (line 1495)
* SCRIPTS <1>:                           Scripts.            (line 5339)
* sharedstate_DATA:                      Data.               (line 5450)
* SOURCES:                               Program Sources.    (line 3542)
* SOURCES <1>:                           Default _SOURCES.   (line 4432)
* SUBDIRS:                               Subdirectories.     (line 3113)
* SUBDIRS <1>:                           Basics of Distribution.
                                                             (line 6375)
* SUFFIXES:                              Suffixes.           (line 7941)
* sysconf_DATA:                          Data.               (line 5450)
* TAGS_DEPENDENCIES:                     Tags.               (line 7911)
* target_triplet:                        Optional.           (line 2121)
* TESTS:                                 Scripts-based Testsuites.
                                                             (line 6772)
* TESTS <1>:                             Parallel Test Harness.
                                                             (line 6873)
* TESTS_ENVIRONMENT:                     Scripts-based Testsuites.
                                                             (line 6772)
* TEST_EXTENSIONS:                       Parallel Test Harness.
                                                             (line 6896)
* TEST_LOGS:                             Parallel Test Harness.
                                                             (line 6896)
* TEST_SUITE_LOG:                        Parallel Test Harness.
                                                             (line 6873)
* TEXI2DVI:                              Texinfo.            (line 6066)
* TEXI2PDF:                              Texinfo.            (line 6071)
* TEXINFOS:                              Uniform.            (line 1495)
* TEXINFOS <1>:                          Texinfo.            (line 5999)
* TEXINFO_TEX:                           Texinfo.            (line 6079)
* top_distdir:                           The dist Hook.      (line 6431)
* top_distdir <1>:                       Third-Party Makefiles.
                                                             (line 8565)
* UPC:                                   Public Macros.      (line 3001)
* UPC <1>:                               Unified Parallel C Support.
                                                             (line 4897)
* UPCCOMPILE:                            Unified Parallel C Support.
                                                             (line 4906)
* UPCFLAGS:                              Unified Parallel C Support.
                                                             (line 4900)
* UPCLINK:                               Unified Parallel C Support.
                                                             (line 4910)
* UPCLINK <1>:                           How the Linker is Chosen.
                                                             (line 5082)
* 'V':                                   Automake Silent Rules.
                                                             (line 8321)
* VALAC:                                 Vala Support.       (line 5212)
* VALAFLAGS:                             Vala Support.       (line 5216)
* VERBOSE:                               Parallel Test Harness.
                                                             (line 6887)
* VERSION:                               Basics of Distribution.
                                                             (line 6338)
* WARNINGS:                              automake Invocation.
                                                             (line 1969)
* WARNINGS <1>:                          aclocal Options.    (line 2444)
* WITH_DMALLOC:                          Public Macros.      (line 3019)
* XFAIL_TESTS:                           Scripts-based Testsuites.
                                                             (line 6718)
* XZ_OPT:                                The Types of Distributions.
                                                             (line 6588)
* YACC:                                  Optional.           (line 2229)
* YFLAGS:                                Yacc and Lex.       (line 4700)

B.3 General Index
=================

* Menu:

* '##' (special Automake comment):       General Operation.  (line 1351)
* '#serial' syntax:                      Serials.            (line 2745)
* '$(LIBOBJS)' and empty libraries:      LIBOBJS.            (line 4551)
* +=:                                    General Operation.  (line 1307)
* --add-missing:                         automake Invocation.
                                                             (line 1843)
* --automake-acdir:                      aclocal Options.    (line 2362)
* --build=BUILD:                         Cross-Compilation.  (line  704)
* --copy:                                automake Invocation.
                                                             (line 1873)
* --diff:                                aclocal Options.    (line 2371)
* --disable-dependency-tracking:         Dependency Tracking.
                                                             (line  901)
* --disable-maintainer-mode:             Optional.           (line 2280)
* --disable-silent-rules:                Automake Silent Rules.
                                                             (line 8318)
* --dry-run:                             aclocal Options.    (line 2376)
* '--enable-debug', example:             Usage of Conditionals.
                                                             (line 8052)
* --enable-dependency-tracking:          Dependency Tracking.
                                                             (line  911)
* --enable-maintainer-mode:              Optional.           (line 2280)
* --enable-silent-rules:                 Automake Silent Rules.
                                                             (line 8318)
* --force:                               aclocal Options.    (line 2398)
* --force-missing:                       automake Invocation.
                                                             (line 1878)
* --foreign:                             automake Invocation.
                                                             (line 1884)
* --gnits:                               automake Invocation.
                                                             (line 1888)
* '--gnits', complete description:       Gnits.              (line 8412)
* --gnu:                                 automake Invocation.
                                                             (line 1892)
* '--gnu', complete description:         Gnits.              (line 8389)
* '--gnu', required files:               Gnits.              (line 8389)
* --help:                                automake Invocation.
                                                             (line 1896)
* --help <1>:                            aclocal Options.    (line 2380)
* '--help' check:                        List of Automake options.
                                                             (line 7781)
* --help=recursive:                      Nested Packages.    (line  944)
* --host=HOST:                           Cross-Compilation.  (line  706)
* --include-deps:                        automake Invocation.
                                                             (line 1904)
* --install:                             aclocal Options.    (line 2387)
* --libdir:                              automake Invocation.
                                                             (line 1863)
* --no-force:                            automake Invocation.
                                                             (line 1909)
* --output:                              aclocal Options.    (line 2408)
* --output-dir:                          automake Invocation.
                                                             (line 1916)
* --prefix:                              Standard Directory Variables.
                                                             (line  465)
* --print-ac-dir:                        aclocal Options.    (line 2411)
* --print-libdir:                        automake Invocation.
                                                             (line 1867)
* --program-prefix=PREFIX:               Renaming.           (line  770)
* --program-suffix=SUFFIX:               Renaming.           (line  772)
* --program-transform-name=PROGRAM:      Renaming.           (line  774)
* --system-acdir:                        aclocal Options.    (line 2366)
* --target=TARGET:                       Cross-Compilation.  (line  745)
* --verbose:                             automake Invocation.
                                                             (line 1923)
* --verbose <1>:                         aclocal Options.    (line 2422)
* --version:                             automake Invocation.
                                                             (line 1927)
* --version <1>:                         aclocal Options.    (line 2425)
* '--version' check:                     List of Automake options.
                                                             (line 7781)
* --warnings:                            automake Invocation.
                                                             (line 1931)
* --warnings <1>:                        aclocal Options.    (line 2429)
* --with-dmalloc:                        Public Macros.      (line 3019)
* -a:                                    automake Invocation.
                                                             (line 1843)
* -c:                                    automake Invocation.
                                                             (line 1872)
* -f:                                    automake Invocation.
                                                             (line 1877)
* '-hook' targets:                       Extending.          (line 8504)
* -i:                                    automake Invocation.
                                                             (line 1900)
* -I:                                    aclocal Options.    (line 2383)
* '-l' and 'LDADD':                      Linking.            (line 3621)
* '-local' targets:                      Extending.          (line 8475)
* '-module', libtool:                    Libtool Modules.    (line 4059)
* -o:                                    automake Invocation.
                                                             (line 1916)
* -v:                                    automake Invocation.
                                                             (line 1923)
* -W:                                    automake Invocation.
                                                             (line 1931)
* -W <1>:                                aclocal Options.    (line 2429)
* -Wall:                                 amhello's configure.ac Setup Explained.
                                                             (line 1153)
* -Werror:                               amhello's configure.ac Setup Explained.
                                                             (line 1153)
* '.la' suffix, defined:                 Libtool Concept.    (line 3818)
* '.log' files:                          Parallel Test Harness.
                                                             (line 6873)
* '.trs' files:                          Parallel Test Harness.
                                                             (line 6873)
* :copy-in-global-log::                  Log files generation and test results recording.
                                                             (line 7225)
* :recheck::                             Log files generation and test results recording.
                                                             (line 7219)
* :test-global-result::                  Log files generation and test results recording.
                                                             (line 7235)
* ':test-result:':                       Log files generation and test results recording.
                                                             (line 7205)
* '_DATA' primary, defined:              Data.               (line 5447)
* '_DEPENDENCIES', defined:              Linking.            (line 3592)
* '_HEADERS' primary, defined:           Headers.            (line 5407)
* '_JAVA' primary, defined:              Java.               (line 5767)
* '_LDFLAGS', defined:                   Linking.            (line 3588)
* '_LDFLAGS', libtool:                   Libtool Flags.      (line 4086)
* '_LIBADD', libtool:                    Libtool Flags.      (line 4086)
* '_LIBRARIES' primary, defined:         A Library.          (line 3751)
* '_LIBTOOLFLAGS', libtool:              Libtool Flags.      (line 4086)
* '_LISP' primary, defined:              Emacs Lisp.         (line 5702)
* '_LTLIBRARIES' primary, defined:       Libtool Libraries.  (line 3855)
* '_MANS' primary, defined:              Man Pages.          (line 6092)
* '_PROGRAMS' primary variable:          Uniform.            (line 1404)
* '_PYTHON' primary, defined:            Python.             (line 5820)
* '_SCRIPTS' primary, defined:           Scripts.            (line 5336)
* '_SOURCES' and header files:           Program Sources.    (line 3548)
* '_SOURCES' primary, defined:           Program Sources.    (line 3541)
* '_SOURCES', default:                   Default _SOURCES.   (line 4432)
* '_SOURCES', empty:                     Default _SOURCES.   (line 4470)
* '_TEXINFOS' primary, defined:          Texinfo.            (line 5940)
* 'acinclude.m4', defined:               Complete.           (line 1717)
* 'aclocal' and serial numbers:          Serials.            (line 2745)
* 'aclocal' program, introduction:       Complete.           (line 1717)
* 'aclocal' search path:                 Macro Search Path.  (line 2450)
* 'aclocal''s scheduled death:           Future of aclocal.  (line 2856)
* 'aclocal', extending:                  Extending aclocal.  (line 2591)
* 'aclocal', Invocation:                 aclocal Invocation. (line 2310)
* 'aclocal', Invoking:                   aclocal Invocation. (line 2310)
* 'aclocal', Options:                    aclocal Options.    (line 2359)
* 'aclocal', using:                      configure.          (line 1984)
* 'aclocal.m4', preexisting:             Complete.           (line 1717)
* 'ACLOCAL_PATH':                        Macro Search Path.  (line 2560)
* 'AC_CONFIG_FILES', conditional:        Usage of Conditionals.
                                                             (line 8110)
* 'AC_SUBST' and 'SUBDIRS':              Subdirectories with AC_SUBST.
                                                             (line 3274)
* Adding new 'SUFFIXES':                 Suffixes.           (line 7941)
* all:                                   Standard Targets.   (line  414)
* all <1>:                               Extending.          (line 8479)
* all-local:                             Extending.          (line 8479)
* 'ALLOCA', and Libtool:                 LTLIBOBJS.          (line 4122)
* 'ALLOCA', example:                     LIBOBJS.            (line 4485)
* 'ALLOCA', special handling:            LIBOBJS.            (line 4485)
* 'amhello-1.0.tar.gz', creation:        Hello World.        (line  984)
* 'amhello-1.0.tar.gz', location:        Use Cases.          (line  308)
* 'amhello-1.0.tar.gz', use cases:       Use Cases.          (line  308)
* 'AM_CCASFLAGS' and 'CCASFLAGS':        Flag Variables Ordering.
                                                             (line 9335)
* 'AM_CFLAGS' and 'CFLAGS':              Flag Variables Ordering.
                                                             (line 9335)
* 'AM_CONDITIONAL' and 'SUBDIRS':        Subdirectories with AM_CONDITIONAL.
                                                             (line 3244)
* 'AM_CPPFLAGS' and 'CPPFLAGS':          Flag Variables Ordering.
                                                             (line 9335)
* 'AM_CXXFLAGS' and 'CXXFLAGS':          Flag Variables Ordering.
                                                             (line 9335)
* 'AM_FCFLAGS' and 'FCFLAGS':            Flag Variables Ordering.
                                                             (line 9335)
* 'AM_FFLAGS' and 'FFLAGS':              Flag Variables Ordering.
                                                             (line 9335)
* 'AM_GCJFLAGS' and 'GCJFLAGS':          Flag Variables Ordering.
                                                             (line 9335)
* 'AM_INIT_AUTOMAKE', example use:       Complete.           (line 1705)
* 'AM_LDFLAGS' and 'LDFLAGS':            Flag Variables Ordering.
                                                             (line 9335)
* 'AM_LFLAGS' and 'LFLAGS':              Flag Variables Ordering.
                                                             (line 9335)
* 'AM_LIBTOOLFLAGS' and 'LIBTOOLFLAGS':  Flag Variables Ordering.
                                                             (line 9335)
* 'AM_MAINTAINER_MODE', purpose:         maintainer-mode.    (line 9037)
* 'AM_OBJCFLAGS' and 'OBJCFLAGS':        Flag Variables Ordering.
                                                             (line 9335)
* 'AM_OBJCXXFLAGS' and 'OBJXXCFLAGS':    Flag Variables Ordering.
                                                             (line 9335)
* 'AM_RFLAGS' and 'RFLAGS':              Flag Variables Ordering.
                                                             (line 9335)
* 'AM_UPCFLAGS' and 'UPCFLAGS':          Flag Variables Ordering.
                                                             (line 9335)
* 'AM_YFLAGS' and 'YFLAGS':              Flag Variables Ordering.
                                                             (line 9335)
* Append operator:                       General Operation.  (line 1307)
* ARG_MAX:                               Length Limitations. (line 1506)
* 'autogen.sh' and 'autoreconf':         Error required file ltmain.sh not found.
                                                             (line 4137)
* autom4te:                              aclocal Invocation. (line 2348)
* Automake constraints:                  Introduction.       (line  222)
* 'automake' options:                    automake Invocation.
                                                             (line 1839)
* Automake parser, limitations of:       General Operation.  (line 1316)
* Automake requirements:                 Introduction.       (line  227)
* Automake requirements <1>:             Requirements.       (line 1996)
* 'automake', invocation:                automake Invocation.
                                                             (line 1808)
* 'automake', invoking:                  automake Invocation.
                                                             (line 1808)
* Automake, recursive operation:         General Operation.  (line 1341)
* Automatic dependency tracking:         Dependencies.       (line 5250)
* Automatic linker selection:            How the Linker is Chosen.
                                                             (line 5072)
* 'autoreconf' and 'libtoolize':         Error required file ltmain.sh not found.
                                                             (line 4137)
* 'autoreconf', example:                 Creating amhello.   (line 1045)
* 'autoscan':                            amhello's configure.ac Setup Explained.
                                                             (line 1204)
* Autotools, introduction:               GNU Build System.   (line  298)
* Autotools, purpose:                    Why Autotools.      (line  952)
* autoupdate:                            Obsolete Macros.    (line 3026)
* Auxiliary programs:                    Auxiliary Programs. (line 1601)
* Avoiding man page renaming:            Man Pages.          (line 6140)
* Avoiding path stripping:               Alternative.        (line 3377)
* Binary package:                        DESTDIR.            (line  805)
* 'bootstrap.sh' and 'autoreconf':       Error required file ltmain.sh not found.
                                                             (line 4137)
* Bugs, reporting:                       Introduction.       (line  231)
* build tree and source tree:            VPATH Builds.       (line  552)
* 'BUILT_SOURCES', defined:              Sources.            (line 5485)
* C++ support:                           C++ Support.        (line 4801)
* canonicalizing Automake variables:     Canonicalization.   (line 1554)
* 'CCASFLAGS' and 'AM_CCASFLAGS':        Flag Variables Ordering.
                                                             (line 9335)
* 'CFLAGS' and 'AM_CFLAGS':              Flag Variables Ordering.
                                                             (line 9335)
* cfortran:                              Mixing Fortran 77 With C and C++.
                                                             (line 5018)
* check:                                 Standard Targets.   (line  429)
* check <1>:                             Tests.              (line 6619)
* check <2>:                             Extending.          (line 8479)
* check-local:                           Extending.          (line 8479)
* check-news:                            List of Automake options.
                                                             (line 7669)
* 'check_' primary prefix, definition:   Uniform.            (line 1489)
* 'check_PROGRAMS' example:              Default _SOURCES.   (line 4454)
* clean:                                 Standard Targets.   (line  425)
* clean <1>:                             Extending.          (line 8479)
* clean-local:                           Clean.              (line 6293)
* clean-local <1>:                       Extending.          (line 8479)
* Colorized testsuite output:            Scripts-based Testsuites.
                                                             (line 6753)
* command line length limit:             Length Limitations. (line 1506)
* Comment, special to Automake:          General Operation.  (line 1351)
* Compilation of Java to bytecode:       Java.               (line 5767)
* Compilation of Java to native code:    Java Support with gcj.
                                                             (line 5154)
* Compile Flag Variables:                Flag Variables Ordering.
                                                             (line 9335)
* Complete example:                      Complete.           (line 1700)
* Conditional example, '--enable-debug': Usage of Conditionals.
                                                             (line 8052)
* conditional libtool libraries:         Conditional Libtool Libraries.
                                                             (line 3895)
* Conditional programs:                  Conditional Programs.
                                                             (line 3707)
* Conditional subdirectories:            Conditional Subdirectories.
                                                             (line 3185)
* Conditional 'SUBDIRS':                 Conditional Subdirectories.
                                                             (line 3185)
* Conditionals:                          Conditionals.       (line 8022)
* 'config.guess':                        automake Invocation.
                                                             (line 1841)
* 'config.site' example:                 config.site.        (line  521)
* configuration variables, overriding:   Standard Configuration Variables.
                                                             (line  484)
* Configuration, basics:                 Basic Installation. (line  329)
* Configure substitutions in 'TESTS':    Parallel Test Harness.
                                                             (line 6908)
* 'configure.ac', Hello World:           amhello's configure.ac Setup Explained.
                                                             (line 1121)
* 'configure.ac', scanning:              configure.          (line 1984)
* conflicting definitions:               Extending.          (line 8452)
* Constraints of Automake:               Introduction.       (line  222)
* convenience libraries, libtool:        Libtool Convenience Libraries.
                                                             (line 3980)
* copying semantics:                     Extending.          (line 8448)
* 'cpio' example:                        Uniform.            (line 1429)
* 'CPPFLAGS' and 'AM_CPPFLAGS':          Flag Variables Ordering.
                                                             (line 9335)
* cross-compilation:                     Cross-Compilation.  (line  696)
* cross-compilation example:             Cross-Compilation.  (line  715)
* CVS and generated files:               CVS.                (line 8874)
* CVS and third-party files:             CVS.                (line 8992)
* CVS and timestamps:                    CVS.                (line 8853)
* 'CXXFLAGS' and 'AM_CXXFLAGS':          Flag Variables Ordering.
                                                             (line 9335)
* 'DATA' primary, defined:               Data.               (line 5447)
* debug build, example:                  VPATH Builds.       (line  592)
* debugging rules:                       Debugging Make Rules.
                                                             (line 9970)
* default source, Libtool modules example: Default _SOURCES. (line 4464)
* default verbosity for silent rules:    Automake Silent Rules.
                                                             (line 8325)
* default '_SOURCES':                    Default _SOURCES.   (line 4432)
* definitions, conflicts:                Extending.          (line 8452)
* dejagnu:                               DejaGnu Tests.      (line 7511)
* dejagnu <1>:                           List of Automake options.
                                                             (line 7673)
* 'depcomp':                             Dependencies.       (line 5261)
* dependencies and distributed files:    Errors with distclean.
                                                             (line 9206)
* Dependency tracking:                   Dependency Tracking.
                                                             (line  874)
* Dependency tracking <1>:               Dependencies.       (line 5250)
* Dependency tracking, disabling:        Dependencies.       (line 5275)
* directory variables:                   Standard Directory Variables.
                                                             (line  438)
* 'dirlist':                             Macro Search Path.  (line 2496)
* Disabling dependency tracking:         Dependencies.       (line 5276)
* Disabling hard errors:                 Scripts-based Testsuites.
                                                             (line 6718)
* dist:                                  Standard Targets.   (line  433)
* dist <1>:                              Basics of Distribution.
                                                             (line 6338)
* dist-bzip2:                            The Types of Distributions.
                                                             (line 6582)
* dist-bzip2 <1>:                        List of Automake options.
                                                             (line 7677)
* dist-bzip2 <2>:                        List of Automake options.
                                                             (line 7677)
* dist-gzip:                             The Types of Distributions.
                                                             (line 6575)
* dist-hook:                             The dist Hook.      (line 6404)
* dist-hook <1>:                         Extending.          (line 8504)
* dist-lzip:                             The Types of Distributions.
                                                             (line 6586)
* dist-lzip <1>:                         List of Automake options.
                                                             (line 7680)
* dist-lzip <2>:                         List of Automake options.
                                                             (line 7680)
* dist-shar:                             The Types of Distributions.
                                                             (line 6609)
* dist-shar <1>:                         List of Automake options.
                                                             (line 7691)
* dist-shar <2>:                         List of Automake options.
                                                             (line 7689)
* dist-tarZ:                             The Types of Distributions.
                                                             (line 6603)
* dist-tarZ <1>:                         List of Automake options.
                                                             (line 7696)
* dist-tarZ <2>:                         List of Automake options.
                                                             (line 7694)
* dist-xz:                               The Types of Distributions.
                                                             (line 6594)
* dist-xz <1>:                           List of Automake options.
                                                             (line 7683)
* dist-xz <2>:                           List of Automake options.
                                                             (line 7683)
* dist-zip:                              The Types of Distributions.
                                                             (line 6597)
* dist-zip <1>:                          List of Automake options.
                                                             (line 7686)
* dist-zip <2>:                          List of Automake options.
                                                             (line 7686)
* distcheck:                             Creating amhello.   (line 1086)
* distcheck <1>:                         Checking the Distribution.
                                                             (line 6453)
* 'distcheck' better than 'dist':        Preparing Distributions.
                                                             (line  840)
* 'distcheck' example:                   Creating amhello.   (line 1086)
* distcheck-hook:                        Checking the Distribution.
                                                             (line 6495)
* distclean:                             Standard Targets.   (line  427)
* distclean <1>:                         Extending.          (line 8479)
* distclean <2>:                         Errors with distclean.
                                                             (line 9206)
* 'distclean', diagnostic:               Errors with distclean.
                                                             (line 9206)
* distclean-local:                       Clean.              (line 6293)
* distclean-local <1>:                   Extending.          (line 8479)
* distcleancheck:                        Checking the Distribution.
                                                             (line 6510)
* distdir:                               Third-Party Makefiles.
                                                             (line 8565)
* Distinction between errors and failures in testsuites: Generalities about Testing.
                                                             (line 6675)
* Distributions, preparation:            Preparing Distributions.
                                                             (line  836)
* distuninstallcheck:                    Checking the Distribution.
                                                             (line 6546)
* 'dist_' and 'nobase_':                 Alternative.        (line 3383)
* 'dist_' and 'notrans_':                Man Pages.          (line 6149)
* 'DIST_SUBDIRS', explained:             SUBDIRS vs DIST_SUBDIRS.
                                                             (line 3213)
* 'dmalloc', support for:                Public Macros.      (line 3019)
* dvi:                                   Texinfo.            (line 5959)
* dvi <1>:                               Extending.          (line 8479)
* DVI output using Texinfo:              Texinfo.            (line 5940)
* dvi-local:                             Extending.          (line 8479)
* E-mail, bug reports:                   Introduction.       (line  231)
* 'EDITION' Texinfo flag:                Texinfo.            (line 5969)
* else:                                  Usage of Conditionals.
                                                             (line 8067)
* Empty libraries:                       A Library.          (line 3793)
* Empty libraries and '$(LIBOBJS)':      LIBOBJS.            (line 4551)
* empty '_SOURCES':                      Default _SOURCES.   (line 4470)
* endif:                                 Usage of Conditionals.
                                                             (line 8067)
* Example conditional '--enable-debug':  Usage of Conditionals.
                                                             (line 8052)
* Example conditional 'AC_CONFIG_FILES': Usage of Conditionals.
                                                             (line 8110)
* Example Hello World:                   Hello World.        (line  984)
* Example of recursive operation:        General Operation.  (line 1341)
* Example of shared libraries:           Libtool Libraries.  (line 3855)
* Example, 'EXTRA_PROGRAMS':             Uniform.            (line 1429)
* Example, 'false' and 'true':           true.               (line 1748)
* Example, mixed language:               Mixing Fortran 77 With C and C++.
                                                             (line 5046)
* Executable extension:                  EXEEXT.             (line 5279)
* Exit status 77, special interpretation: Scripts-based Testsuites.
                                                             (line 6713)
* Exit status 99, special interpretation: Scripts-based Testsuites.
                                                             (line 6713)
* expected failure:                      Generalities about Testing.
                                                             (line 6666)
* expected test failure:                 Generalities about Testing.
                                                             (line 6666)
* Expected test failure:                 Scripts-based Testsuites.
                                                             (line 6718)
* Extending 'aclocal':                   Extending aclocal.  (line 2591)
* Extending list of installation directories: Uniform.       (line 1449)
* Extension, executable:                 EXEEXT.             (line 5279)
* Extra files distributed with Automake: automake Invocation.
                                                             (line 1841)
* 'EXTRA_', prepending:                  Uniform.            (line 1422)
* 'EXTRA_PROGRAMS', defined:             Uniform.            (line 1429)
* 'EXTRA_PROGRAMS', defined <1>:         Conditional Programs.
                                                             (line 3716)
* 'EXTRA_prog_SOURCES', defined:         Conditional Sources.
                                                             (line 3643)
* 'false' Example:                       true.               (line 1748)
* 'FCFLAGS' and 'AM_FCFLAGS':            Flag Variables Ordering.
                                                             (line 9335)
* Features of the GNU Build System:      Use Cases.          (line  308)
* 'FFLAGS' and 'AM_FFLAGS':              Flag Variables Ordering.
                                                             (line 9335)
* file names, limitations on:            Limitations on File Names.
                                                             (line 9150)
* filename-length-max=99:                List of Automake options.
                                                             (line 7699)
* Files distributed with Automake:       automake Invocation.
                                                             (line 1841)
* First line of Makefile.am:             General Operation.  (line 1357)
* Flag variables, ordering:              Flag Variables Ordering.
                                                             (line 9321)
* Flag Variables, Ordering:              Flag Variables Ordering.
                                                             (line 9335)
* 'FLIBS', defined:                      Mixing Fortran 77 With C and C++.
                                                             (line 5033)
* foreign:                               amhello's configure.ac Setup Explained.
                                                             (line 1153)
* foreign <1>:                           List of Automake options.
                                                             (line 7664)
* 'foreign' strictness:                  Strictness.         (line 1366)
* Fortran 77 support:                    Fortran 77 Support. (line 4938)
* Fortran 77, mixing with C and C++:     Mixing Fortran 77 With C and C++.
                                                             (line 5018)
* Fortran 77, Preprocessing:             Preprocessing Fortran 77.
                                                             (line 4987)
* Fortran 9x support:                    Fortran 9x Support. (line 5105)
* 'GCJFLAGS' and 'AM_GCJFLAGS':          Flag Variables Ordering.
                                                             (line 9335)
* generated files and CVS:               CVS.                (line 8874)
* generated files, distributed:          CVS.                (line 8834)
* Gettext support:                       gettext.            (line 5747)
* git-dist:                              General Operation.  (line 1295)
* 'git-dist', non-standard example:      General Operation.  (line 1295)
* gnits:                                 List of Automake options.
                                                             (line 7664)
* 'gnits' strictness:                    Strictness.         (line 1366)
* gnu:                                   List of Automake options.
                                                             (line 7664)
* GNU Build System, basics:              Basic Installation. (line  329)
* GNU Build System, features:            Use Cases.          (line  308)
* GNU Build System, introduction:        GNU Build System.   (line  261)
* GNU Build System, use cases:           Use Cases.          (line  308)
* GNU Coding Standards:                  GNU Build System.   (line  284)
* GNU Gettext support:                   gettext.            (line 5747)
* GNU make extensions:                   General Operation.  (line 1303)
* GNU Makefile standards:                Introduction.       (line  213)
* 'gnu' strictness:                      Strictness.         (line 1366)
* 'GNUmakefile' including 'Makefile':    Third-Party Makefiles.
                                                             (line 8651)
* hard error:                            Generalities about Testing.
                                                             (line 6675)
* Header files in '_SOURCES':            Program Sources.    (line 3548)
* 'HEADERS' primary, defined:            Headers.            (line 5407)
* 'HEADERS', installation directories:   Headers.            (line 5407)
* Hello World example:                   Hello World.        (line  984)
* hook targets:                          Extending.          (line 8504)
* HP-UX 10, 'lex' problems:              Public Macros.      (line 2991)
* html:                                  Texinfo.            (line 5959)
* html <1>:                              Extending.          (line 8479)
* HTML output using Texinfo:             Texinfo.            (line 5940)
* html-local:                            Extending.          (line 8479)
* id:                                    Tags.               (line 7919)
* if:                                    Usage of Conditionals.
                                                             (line 8067)
* include:                               Basics of Distribution.
                                                             (line 6345)
* include <1>:                           Include.            (line 7982)
* 'include', distribution:               Basics of Distribution.
                                                             (line 6345)
* Including 'Makefile' fragment:         Include.            (line 7982)
* indentation in Makefile.am:            General Operation.  (line 1316)
* info:                                  List of Automake options.
                                                             (line 7745)
* info <1>:                              Extending.          (line 8479)
* info-in-builddir:                      List of Automake options.
                                                             (line 7708)
* info-local:                            Extending.          (line 8479)
* install:                               Standard Targets.   (line  416)
* install <1>:                           The Two Parts of Install.
                                                             (line 6208)
* install <2>:                           Extending.          (line 8479)
* Install hook:                          Extending Installation.
                                                             (line 6237)
* Install, two parts of:                 The Two Parts of Install.
                                                             (line 6208)
* install-data:                          Two-Part Install.   (line  654)
* install-data <1>:                      The Two Parts of Install.
                                                             (line 6208)
* install-data <2>:                      Extending.          (line 8479)
* install-data-hook:                     Extending.          (line 8504)
* install-data-local:                    Extending Installation.
                                                             (line 6231)
* install-data-local <1>:                Extending.          (line 8479)
* install-dvi:                           Texinfo.            (line 5959)
* install-dvi <1>:                       Extending.          (line 8479)
* install-dvi-local:                     Extending.          (line 8479)
* install-exec:                          Two-Part Install.   (line  654)
* install-exec <1>:                      The Two Parts of Install.
                                                             (line 6208)
* install-exec <2>:                      Extending.          (line 8479)
* install-exec-hook:                     Extending.          (line 8504)
* install-exec-local:                    Extending Installation.
                                                             (line 6231)
* install-exec-local <1>:                Extending.          (line 8479)
* install-html:                          Texinfo.            (line 5959)
* install-html <1>:                      Extending.          (line 8479)
* install-html-local:                    Extending.          (line 8479)
* install-info:                          Texinfo.            (line 6019)
* install-info <1>:                      List of Automake options.
                                                             (line 7745)
* install-info <2>:                      Extending.          (line 8479)
* 'install-info' target:                 Texinfo.            (line 6019)
* install-info-local:                    Extending.          (line 8479)
* install-man:                           Man Pages.          (line 6118)
* install-man <1>:                       List of Automake options.
                                                             (line 7751)
* 'install-man' target:                  Man Pages.          (line 6118)
* install-pdf:                           Texinfo.            (line 5959)
* install-pdf <1>:                       Extending.          (line 8479)
* install-pdf-local:                     Extending.          (line 8479)
* install-ps:                            Texinfo.            (line 5959)
* install-ps <1>:                        Extending.          (line 8479)
* install-ps-local:                      Extending.          (line 8479)
* install-strip:                         Standard Targets.   (line  419)
* install-strip <1>:                     Install Rules for the User.
                                                             (line 6272)
* Installation directories, extending list: Uniform.         (line 1449)
* Installation support:                  Install.            (line 6158)
* Installation, basics:                  Basic Installation. (line  329)
* installcheck:                          Standard Targets.   (line  431)
* installcheck <1>:                      Extending.          (line 8479)
* installcheck-local:                    Extending.          (line 8479)
* installdirs:                           Install Rules for the User.
                                                             (line 6272)
* installdirs <1>:                       Extending.          (line 8479)
* installdirs-local:                     Extending.          (line 8479)
* Installing headers:                    Headers.            (line 5407)
* Installing scripts:                    Scripts.            (line 5336)
* installing versioned binaries:         Extending.          (line 8524)
* Interfacing with third-party packages: Third-Party Makefiles.
                                                             (line 8546)
* Invocation of 'aclocal':               aclocal Invocation. (line 2310)
* Invocation of 'automake':              automake Invocation.
                                                             (line 1808)
* Invoking 'aclocal':                    aclocal Invocation. (line 2310)
* Invoking 'automake':                   automake Invocation.
                                                             (line 1808)
* 'JAVA' primary, defined:               Java.               (line 5767)
* 'JAVA' restrictions:                   Java.               (line 5786)
* Java support with gcj:                 Java Support with gcj.
                                                             (line 5154)
* Java to bytecode, compilation:         Java.               (line 5767)
* Java to native code, compilation:      Java Support with gcj.
                                                             (line 5154)
* lazy test execution:                   Parallel Test Harness.
                                                             (line 6980)
* 'LDADD' and '-l':                      Linking.            (line 3621)
* 'LDFLAGS' and 'AM_LDFLAGS':            Flag Variables Ordering.
                                                             (line 9335)
* 'lex' problems with HP-UX 10:          Public Macros.      (line 2991)
* 'lex', multiple lexers:                Yacc and Lex.       (line 4731)
* 'LFLAGS' and 'AM_LFLAGS':              Flag Variables Ordering.
                                                             (line 9335)
* 'libltdl', introduction:               Libtool Concept.    (line 3841)
* 'LIBOBJS', and Libtool:                LTLIBOBJS.          (line 4122)
* 'LIBOBJS', example:                    LIBOBJS.            (line 4485)
* 'LIBOBJS', special handling:           LIBOBJS.            (line 4485)
* 'LIBRARIES' primary, defined:          A Library.          (line 3751)
* libtool convenience libraries:         Libtool Convenience Libraries.
                                                             (line 3980)
* libtool libraries, conditional:        Conditional Libtool Libraries.
                                                             (line 3895)
* libtool library, definition:           Libtool Concept.    (line 3818)
* libtool modules:                       Libtool Modules.    (line 4059)
* Libtool modules, default source example: Default _SOURCES. (line 4464)
* 'libtool', introduction:               Libtool Concept.    (line 3818)
* 'LIBTOOLFLAGS' and 'AM_LIBTOOLFLAGS':  Flag Variables Ordering.
                                                             (line 9335)
* 'libtoolize' and 'autoreconf':         Error required file ltmain.sh not found.
                                                             (line 4137)
* 'libtoolize', no longer run by 'automake': Error required file ltmain.sh not found.
                                                             (line 4137)
* Limitations of automake parser:        General Operation.  (line 1316)
* Linking Fortran 77 with C and C++:     Mixing Fortran 77 With C and C++.
                                                             (line 5018)
* 'LISP' primary, defined:               Emacs Lisp.         (line 5702)
* 'LN_S' example:                        Extending.          (line 8524)
* local targets:                         Extending.          (line 8475)
* 'LTALLOCA', special handling:          LTLIBOBJS.          (line 4122)
* 'LTLIBOBJS', special handling:         LTLIBOBJS.          (line 4122)
* 'LTLIBRARIES' primary, defined:        Libtool Libraries.  (line 3855)
* 'ltmain.sh' not found:                 Error required file ltmain.sh not found.
                                                             (line 4137)
* 'm4_include', distribution:            Basics of Distribution.
                                                             (line 6345)
* Macro search path:                     Macro Search Path.  (line 2450)
* macro serial numbers:                  Serials.            (line 2745)
* Macros Automake recognizes:            Optional.           (line 2113)
* maintainer-clean-local:                Clean.              (line 6293)
* 'make check':                          Tests.              (line 6619)
* 'make clean' support:                  Clean.              (line 6284)
* 'make dist':                           Basics of Distribution.
                                                             (line 6338)
* 'make distcheck':                      Checking the Distribution.
                                                             (line 6453)
* 'make distclean', diagnostic:          Errors with distclean.
                                                             (line 9206)
* 'make distcleancheck':                 Checking the Distribution.
                                                             (line 6510)
* 'make distuninstallcheck':             Checking the Distribution.
                                                             (line 6546)
* 'make install' support:                Install.            (line 6158)
* 'make installcheck', testing '--help' and '--version': List of Automake options.
                                                             (line 7781)
* Make rules, overriding:                General Operation.  (line 1329)
* Make targets, overriding:              General Operation.  (line 1329)
* 'Makefile' fragment, including:        Include.            (line 7982)
* Makefile.am, first line:               General Operation.  (line 1357)
* 'Makefile.am', Hello World:            amhello's Makefile.am Setup Explained.
                                                             (line 1213)
* Man page renaming, avoiding:           Man Pages.          (line 6140)
* 'MANS' primary, defined:               Man Pages.          (line 6092)
* many outputs, rules with:              Multiple Outputs.   (line 9581)
* 'mdate-sh':                            Texinfo.            (line 5969)
* MinGW cross-compilation example:       Cross-Compilation.  (line  715)
* 'missing', purpose:                    maintainer-mode.    (line 9009)
* Mixed language example:                Mixing Fortran 77 With C and C++.
                                                             (line 5046)
* Mixing Fortran 77 with C and C++:      Mixing Fortran 77 With C and C++.
                                                             (line 5018)
* Mixing Fortran 77 with C and/or C++:   Mixing Fortran 77 With C and C++.
                                                             (line 5018)
* 'mkdir -p', macro check:               Obsolete Macros.    (line 3034)
* modules, libtool:                      Libtool Modules.    (line 4059)
* mostlyclean:                           Extending.          (line 8479)
* mostlyclean-local:                     Clean.              (line 6293)
* mostlyclean-local <1>:                 Extending.          (line 8479)
* multiple configurations, example:      VPATH Builds.       (line  592)
* Multiple 'configure.ac' files:         automake Invocation.
                                                             (line 1808)
* Multiple 'lex' lexers:                 Yacc and Lex.       (line 4731)
* multiple outputs, rules with:          Multiple Outputs.   (line 9581)
* Multiple 'yacc' parsers:               Yacc and Lex.       (line 4731)
* Nested packages:                       Nested Packages.    (line  920)
* Nesting packages:                      Subpackages.        (line 3414)
* no-define:                             Public Macros.      (line 2951)
* no-define <1>:                         List of Automake options.
                                                             (line 7713)
* no-dependencies:                       Dependencies.       (line 5273)
* no-dependencies <1>:                   List of Automake options.
                                                             (line 7718)
* no-dist:                               List of Automake options.
                                                             (line 7725)
* no-dist-gzip:                          List of Automake options.
                                                             (line 7729)
* no-dist-gzip <1>:                      List of Automake options.
                                                             (line 7729)
* no-exeext:                             List of Automake options.
                                                             (line 7732)
* no-installinfo:                        Texinfo.            (line 6019)
* no-installinfo <1>:                    List of Automake options.
                                                             (line 7742)
* 'no-installinfo' option:               Texinfo.            (line 6019)
* no-installman:                         Man Pages.          (line 6118)
* no-installman <1>:                     List of Automake options.
                                                             (line 7748)
* 'no-installman' option:                Man Pages.          (line 6118)
* no-texinfo.tex:                        List of Automake options.
                                                             (line 7758)
* 'nobase_' and 'dist_' or 'nodist_':    Alternative.        (line 3383)
* 'nobase_' prefix:                      Alternative.        (line 3377)
* 'nodist_' and 'nobase_':               Alternative.        (line 3383)
* 'nodist_' and 'notrans_':              Man Pages.          (line 6149)
* 'noinst_' primary prefix, definition:  Uniform.            (line 1484)
* Non-GNU packages:                      Strictness.         (line 1362)
* Non-standard targets:                  General Operation.  (line 1295)
* nostdinc:                              List of Automake options.
                                                             (line 7754)
* 'notrans_' and 'dist_' or 'nodist_':   Man Pages.          (line 6149)
* 'notrans_' prefix:                     Man Pages.          (line 6140)
* 'OBJCFLAGS' and 'AM_OBJCFLAGS':        Flag Variables Ordering.
                                                             (line 9335)
* 'OBJCXXFLAGS' and 'AM_OBJCXXFLAGS':    Flag Variables Ordering.
                                                             (line 9335)
* Objective C support:                   Objective C Support.
                                                             (line 4830)
* Objective C++ support:                 Objective C++ Support.
                                                             (line 4859)
* Objects in subdirectory:               Program and Library Variables.
                                                             (line 4247)
* obsolete macros:                       Obsolete Macros.    (line 3026)
* optimized build, example:              VPATH Builds.       (line  592)
* Option, '--warnings=CATEGORY':         List of Automake options.
                                                             (line 7863)
* Option, '-WCATEGORY':                  List of Automake options.
                                                             (line 7863)
* Option, 'check-news':                  List of Automake options.
                                                             (line 7669)
* Option, 'dejagnu':                     List of Automake options.
                                                             (line 7673)
* Option, 'dist-bzip2':                  List of Automake options.
                                                             (line 7677)
* Option, 'dist-lzip':                   List of Automake options.
                                                             (line 7680)
* Option, 'dist-shar':                   List of Automake options.
                                                             (line 7689)
* Option, 'dist-tarZ':                   List of Automake options.
                                                             (line 7694)
* Option, 'dist-xz':                     List of Automake options.
                                                             (line 7683)
* Option, 'dist-zip':                    List of Automake options.
                                                             (line 7686)
* Option, 'filename-length-max=99':      List of Automake options.
                                                             (line 7699)
* Option, 'foreign':                     List of Automake options.
                                                             (line 7664)
* Option, 'gnits':                       List of Automake options.
                                                             (line 7664)
* Option, 'gnu':                         List of Automake options.
                                                             (line 7664)
* Option, 'info-in-builddir':            List of Automake options.
                                                             (line 7708)
* Option, 'no-define':                   List of Automake options.
                                                             (line 7713)
* Option, 'no-dependencies':             List of Automake options.
                                                             (line 7718)
* Option, 'no-dist':                     List of Automake options.
                                                             (line 7725)
* Option, 'no-dist-gzip':                List of Automake options.
                                                             (line 7729)
* Option, 'no-exeext':                   List of Automake options.
                                                             (line 7732)
* Option, 'no-installinfo':              Texinfo.            (line 6019)
* Option, 'no-installinfo' <1>:          List of Automake options.
                                                             (line 7742)
* Option, 'no-installman':               Man Pages.          (line 6118)
* Option, 'no-installman' <1>:           List of Automake options.
                                                             (line 7748)
* Option, 'no-texinfo.tex':              List of Automake options.
                                                             (line 7758)
* Option, 'nostdinc':                    List of Automake options.
                                                             (line 7754)
* Option, 'parallel-tests':              List of Automake options.
                                                             (line 7766)
* Option, 'readme-alpha':                List of Automake options.
                                                             (line 7772)
* Option, 'serial-tests':                List of Automake options.
                                                             (line 7762)
* Option, 'tar-pax':                     List of Automake options.
                                                             (line 7811)
* Option, 'tar-ustar':                   List of Automake options.
                                                             (line 7811)
* Option, 'tar-v7':                      List of Automake options.
                                                             (line 7811)
* Option, VERSION:                       List of Automake options.
                                                             (line 7858)
* Option, warnings:                      List of Automake options.
                                                             (line 7863)
* Options, 'aclocal':                    aclocal Options.    (line 2359)
* Options, 'automake':                   automake Invocation.
                                                             (line 1839)
* Options, 'std-options':                List of Automake options.
                                                             (line 7781)
* Options, 'subdir-objects':             List of Automake options.
                                                             (line 7802)
* Ordering flag variables:               Flag Variables Ordering.
                                                             (line 9321)
* Overriding make rules:                 General Operation.  (line 1329)
* Overriding make targets:               General Operation.  (line 1329)
* Overriding make variables:             General Operation.  (line 1334)
* overriding rules:                      Extending.          (line 8464)
* overriding semantics:                  Extending.          (line 8464)
* 'PACKAGE', directory:                  Uniform.            (line 1412)
* 'PACKAGE', prevent definition:         Public Macros.      (line 2951)
* Packages, nested:                      Nested Packages.    (line  920)
* Packages, preparation:                 Preparing Distributions.
                                                             (line  836)
* Parallel build trees:                  VPATH Builds.       (line  552)
* parallel-tests:                        List of Automake options.
                                                             (line 7766)
* Path stripping, avoiding:              Alternative.        (line 3377)
* pax format:                            List of Automake options.
                                                             (line 7811)
* pdf:                                   Texinfo.            (line 5959)
* pdf <1>:                               Extending.          (line 8479)
* PDF output using Texinfo:              Texinfo.            (line 5940)
* pdf-local:                             Extending.          (line 8479)
* Per-object flags, emulated:            Per-Object Flags.   (line 9522)
* per-target compilation flags, defined: Program and Library Variables.
                                                             (line 4378)
* 'pkgdatadir', defined:                 Uniform.            (line 1412)
* 'pkgincludedir', defined:              Uniform.            (line 1412)
* 'pkglibdir', defined:                  Uniform.            (line 1412)
* 'pkglibexecdir', defined:              Uniform.            (line 1412)
* Preparing distributions:               Preparing Distributions.
                                                             (line  836)
* Preprocessing Fortran 77:              Preprocessing Fortran 77.
                                                             (line 4987)
* Primary variable, 'DATA':              Data.               (line 5447)
* Primary variable, defined:             Uniform.            (line 1404)
* Primary variable, 'HEADERS':           Headers.            (line 5407)
* Primary variable, 'JAVA':              Java.               (line 5767)
* Primary variable, 'LIBRARIES':         A Library.          (line 3751)
* Primary variable, 'LISP':              Emacs Lisp.         (line 5702)
* Primary variable, 'LTLIBRARIES':       Libtool Libraries.  (line 3855)
* Primary variable, 'MANS':              Man Pages.          (line 6092)
* Primary variable, 'PROGRAMS':          Uniform.            (line 1404)
* Primary variable, 'PYTHON':            Python.             (line 5820)
* Primary variable, 'SCRIPTS':           Scripts.            (line 5336)
* Primary variable, 'SOURCES':           Program Sources.    (line 3541)
* Primary variable, 'TEXINFOS':          Texinfo.            (line 5940)
* 'PROGRAMS' primary variable:           Uniform.            (line 1404)
* Programs, auxiliary:                   Auxiliary Programs. (line 1601)
* 'PROGRAMS', 'bindir':                  Program Sources.    (line 3515)
* Programs, conditional:                 Conditional Programs.
                                                             (line 3707)
* Programs, renaming during installation: Renaming.          (line  760)
* 'prog_LDADD', defined:                 Linking.            (line 3563)
* Proxy 'Makefile' for third-party packages: Third-Party Makefiles.
                                                             (line 8668)
* ps:                                    Texinfo.            (line 5959)
* ps <1>:                                Extending.          (line 8479)
* PS output using Texinfo:               Texinfo.            (line 5940)
* ps-local:                              Extending.          (line 8479)
* 'PYTHON' primary, defined:             Python.             (line 5820)
* Ratfor programs:                       Preprocessing Fortran 77.
                                                             (line 4987)
* read-only source tree:                 VPATH Builds.       (line  635)
* readme-alpha:                          List of Automake options.
                                                             (line 7772)
* 'README-alpha':                        Gnits.              (line 8425)
* rebuild rules:                         Rebuilding.         (line 7546)
* rebuild rules <1>:                     CVS.                (line 8834)
* recheck:                               Parallel Test Harness.
                                                             (line 6992)
* Recognized macros by Automake:         Optional.           (line 2113)
* Recursive operation of Automake:       General Operation.  (line 1341)
* recursive targets and third-party 'Makefile's: Third-Party Makefiles.
                                                             (line 8555)
* Register test case result:             Log files generation and test results recording.
                                                             (line 7205)
* Register test result:                  Log files generation and test results recording.
                                                             (line 7205)
* Renaming programs:                     Renaming.           (line  760)
* Reporting bugs:                        Introduction.       (line  231)
* Requirements of Automake:              Requirements.       (line 1996)
* Requirements, Automake:                Introduction.       (line  227)
* Restrictions for 'JAVA':               Java.               (line 5786)
* reStructuredText field, ':copy-in-global-log:': Log files generation and test results recording.
                                                             (line 7225)
* reStructuredText field, ':recheck:':   Log files generation and test results recording.
                                                             (line 7219)
* reStructuredText field, ':test-global-result:': Log files generation and test results recording.
                                                             (line 7235)
* reStructuredText field, ':test-result:': Log files generation and test results recording.
                                                             (line 7205)
* 'RFLAGS' and 'AM_RFLAGS':              Flag Variables Ordering.
                                                             (line 9335)
* rules with multiple outputs:           Multiple Outputs.   (line 9581)
* rules, conflicting:                    Extending.          (line 8452)
* rules, debugging:                      Debugging Make Rules.
                                                             (line 9970)
* rules, overriding:                     Extending.          (line 8464)
* Scanning 'configure.ac':               configure.          (line 1984)
* 'SCRIPTS' primary, defined:            Scripts.            (line 5336)
* 'SCRIPTS', installation directories:   Scripts.            (line 5348)
* Selecting the linker automatically:    How the Linker is Chosen.
                                                             (line 5072)
* serial number and '--install':         aclocal Options.    (line 2391)
* serial numbers in macros:              Serials.            (line 2745)
* serial-tests:                          List of Automake options.
                                                             (line 7762)
* 'serial-tests', Using:                 Serial Test Harness.
                                                             (line 6829)
* Shared libraries, support for:         A Shared Library.   (line 3811)
* Silencing 'make':                      Silencing Make.     (line 8156)
* Silent 'make':                         Silencing Make.     (line 8156)
* Silent 'make' rules:                   Silencing Make.     (line 8156)
* Silent rules:                          Silencing Make.     (line 8156)
* silent rules and libtool:              Automake Silent Rules.
                                                             (line 8292)
* 'site.exp':                            DejaGnu Tests.      (line 7518)
* source tree and build tree:            VPATH Builds.       (line  552)
* source tree, read-only:                VPATH Builds.       (line  635)
* 'SOURCES' primary, defined:            Program Sources.    (line 3541)
* Special Automake comment:              General Operation.  (line 1351)
* Staged installation:                   DESTDIR.            (line  797)
* std-options:                           List of Automake options.
                                                             (line 7781)
* Strictness, command line:              automake Invocation.
                                                             (line 1839)
* Strictness, defined:                   Strictness.         (line 1366)
* Strictness, 'foreign':                 Strictness.         (line 1366)
* Strictness, 'gnits':                   Strictness.         (line 1366)
* Strictness, 'gnu':                     Strictness.         (line 1366)
* su, before 'make install':             Basic Installation. (line  372)
* subdir-objects:                        List of Automake options.
                                                             (line 7802)
* Subdirectories, building conditionally: Conditional Subdirectories.
                                                             (line 3185)
* Subdirectories, configured conditionally: Unconfigured Subdirectories.
                                                             (line 3298)
* Subdirectories, not distributed:       Unconfigured Subdirectories.
                                                             (line 3347)
* Subdirectory, objects in:              Program and Library Variables.
                                                             (line 4247)
* 'SUBDIRS' and 'AC_SUBST':              Subdirectories with AC_SUBST.
                                                             (line 3274)
* 'SUBDIRS' and 'AM_CONDITIONAL':        Subdirectories with AM_CONDITIONAL.
                                                             (line 3244)
* 'SUBDIRS', conditional:                Conditional Subdirectories.
                                                             (line 3185)
* 'SUBDIRS', explained:                  Subdirectories.     (line 3111)
* Subpackages:                           Nested Packages.    (line  920)
* Subpackages <1>:                       Subpackages.        (line 3414)
* suffix '.la', defined:                 Libtool Concept.    (line 3818)
* suffix '.lo', defined:                 Libtool Concept.    (line 3827)
* 'SUFFIXES', adding:                    Suffixes.           (line 7941)
* Support for C++:                       C++ Support.        (line 4801)
* Support for Fortran 77:                Fortran 77 Support. (line 4938)
* Support for Fortran 9x:                Fortran 9x Support. (line 5105)
* Support for GNU Gettext:               gettext.            (line 5747)
* Support for Java with gcj:             Java Support with gcj.
                                                             (line 5154)
* Support for Objective C:               Objective C Support.
                                                             (line 4830)
* Support for Objective C++:             Objective C++ Support.
                                                             (line 4859)
* Support for Unified Parallel C:        Unified Parallel C Support.
                                                             (line 4888)
* Support for Vala:                      Vala Support.       (line 5184)
* tags:                                  Tags.               (line 7885)
* 'TAGS' support:                        Tags.               (line 7882)
* 'tar' formats:                         List of Automake options.
                                                             (line 7811)
* tar-pax:                               List of Automake options.
                                                             (line 7811)
* tar-ustar:                             List of Automake options.
                                                             (line 7811)
* tar-v7:                                List of Automake options.
                                                             (line 7811)
* Target, 'install-info':                Texinfo.            (line 6019)
* Target, 'install-man':                 Man Pages.          (line 6118)
* test case:                             Generalities about Testing.
                                                             (line 6638)
* Test case result, registering:         Log files generation and test results recording.
                                                             (line 7205)
* test failure:                          Generalities about Testing.
                                                             (line 6652)
* test harness:                          Generalities about Testing.
                                                             (line 6645)
* test metadata:                         Parallel Test Harness.
                                                             (line 6873)
* test pass:                             Generalities about Testing.
                                                             (line 6652)
* Test result, registering:              Log files generation and test results recording.
                                                             (line 7205)
* test skip:                             Generalities about Testing.
                                                             (line 6656)
* Test suites:                           Tests.              (line 6619)
* Tests, expected failure:               Scripts-based Testsuites.
                                                             (line 6718)
* testsuite harness:                     Generalities about Testing.
                                                             (line 6645)
* Testsuite progress on console:         Scripts-based Testsuites.
                                                             (line 6731)
* Texinfo flag, 'EDITION':               Texinfo.            (line 5969)
* Texinfo flag, 'UPDATED':               Texinfo.            (line 5969)
* Texinfo flag, 'UPDATED-MONTH':         Texinfo.            (line 5969)
* Texinfo flag, 'VERSION':               Texinfo.            (line 5969)
* 'texinfo.tex':                         Texinfo.            (line 6004)
* 'TEXINFOS' primary, defined:           Texinfo.            (line 5940)
* third-party files and CVS:             CVS.                (line 8992)
* Third-party packages, interfacing with: Third-Party Makefiles.
                                                             (line 8546)
* timestamps and CVS:                    CVS.                (line 8853)
* Transforming program names:            Renaming.           (line  760)
* trees, source vs. build:               VPATH Builds.       (line  552)
* 'true' Example:                        true.               (line 1748)
* underquoted 'AC_DEFUN':                Extending aclocal.  (line 2621)
* unexpected pass:                       Generalities about Testing.
                                                             (line 6666)
* unexpected test pass:                  Generalities about Testing.
                                                             (line 6666)
* Unified Parallel C support:            Unified Parallel C Support.
                                                             (line 4888)
* Uniform naming scheme:                 Uniform.            (line 1399)
* uninstall:                             Standard Targets.   (line  422)
* uninstall <1>:                         Install Rules for the User.
                                                             (line 6272)
* uninstall <2>:                         Extending.          (line 8479)
* uninstall-hook:                        Extending.          (line 8504)
* uninstall-local:                       Extending.          (line 8479)
* Unit tests:                            Parallel Test Harness.
                                                             (line 7016)
* Unpacking:                             Basic Installation. (line  350)
* 'UPCFLAGS' and 'AM_UPCFLAGS':          Flag Variables Ordering.
                                                             (line 9335)
* 'UPDATED' Texinfo flag:                Texinfo.            (line 5969)
* 'UPDATED-MONTH' Texinfo flag:          Texinfo.            (line 5969)
* Use Cases for the GNU Build System:    Use Cases.          (line  308)
* user variables:                        User Variables.     (line 1574)
* Using 'aclocal':                       configure.          (line 1984)
* ustar format:                          List of Automake options.
                                                             (line 7811)
* v7 'tar' format:                       List of Automake options.
                                                             (line 7811)
* Vala Support:                          Vala Support.       (line 5184)
* variables, conflicting:                Extending.          (line 8452)
* Variables, overriding:                 General Operation.  (line 1334)
* variables, reserved for the user:      User Variables.     (line 1574)
* 'VERSION' Texinfo flag:                Texinfo.            (line 5969)
* 'VERSION', prevent definition:         Public Macros.      (line 2951)
* 'version.m4', example:                 Rebuilding.         (line 7552)
* 'version.sh', example:                 Rebuilding.         (line 7552)
* versioned binaries, installing:        Extending.          (line 8524)
* VPATH builds:                          VPATH Builds.       (line  552)
* wildcards:                             Wildcards.          (line 9084)
* Windows:                               EXEEXT.             (line 5279)
* xfail:                                 Generalities about Testing.
                                                             (line 6666)
* xpass:                                 Generalities about Testing.
                                                             (line 6666)
* 'yacc', multiple parsers:              Yacc and Lex.       (line 4731)
* 'YFLAGS' and 'AM_YFLAGS':              Flag Variables Ordering.
                                                             (line 9335)
* 'ylwrap':                              Yacc and Lex.       (line 4731)
* 'zardoz' example:                      Complete.           (line 1729)