centos7 修改yum源为阿里源

1.安装base reop源

   cd /etc/yum.repos.d

接着备份旧的配置文件

   sudo mv CentOS-Base.repo CentOS-Base.repo.bak

下载阿里源的文件

   sudo wget -O CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo

2 安装epel repo源：

epel(RHEL 7)

    wget -O /etc/yum.repos.d/epel.repo http://mirrors.aliyun.com/repo/epel-7.repo

epel(RHEL 6)

    wget -O /etc/yum.repos.d/epel.repo http://mirrors.aliyun.com/repo/epel-6.repo

epel(RHEL 5)

    wget -O /etc/yum.repos.d/epel.repo http://mirrors.aliyun.com/repo/epel-5.repo

3.清理缓存

yum clean all

4.重新生成缓存

yum makecache