CentOS 7 换源

1.备份原yum源文件

mv /etc/yum.repos.d/CentOS- Base.repo /etc/yum.repos.d/CentOS- Base.repo.backup

2.下载阿里源

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

3.清除缓存&&更新缓存

yum clean all 清除缓存

yum makecache 更新缓存