centos 7 切换yum源为阿里云源
1 . 切到 /etc/yum.repos.d/ 目录,并备份原本的yum
cd /etc/yum.repos.d/
mv CentOS-Base.repo CentOS-Base.repo.bak
2. 下载阿里云的yum,并切换到阿里源
wget http://mirrors.aliyun.com/repo/Centos-7.repo
mv Centos-7.repo CentOS-Base.repo
3. 清理并执行yum源更新命令
yum clean all && yum makecache
4. yum更新
yum -y update