CentOS7 更改yum源为阿里云的

备份

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

下载阿里云的源配置

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

更新

yum makecache