yum报错Error: Cannot retrieve repository metadata (repomd.xml) for repository: rhel-source

思路：

rm -fr /etc/yum.repo.d/* #删除下面内容

wget http://mirrors.aliyun.com/repo/Centos-7.repo

wget http://mirrors.aliyun.com/repo/Centos-6.repo #从三个任一选择一个下载

wget http://mirrors.aliyun.com/repo/Centos-5.repo

yum clean all #清除

yum makecache #重新加载缓存