更换yum源

更换阿里yum源

cd /etc/yum.repos.d/
mv CentOS-Base.repo CentOS-Base.repo.bak
wget http://mirrors.aliyun.com/repo/Centos-7.repo && mv Centos-7.repo CentOS-Base.repo
yum clean all && yum makecache && yum update -y