centos 设置阿里的yum源

rm /etc/yum.repos.d/CentOS-Base.repo

curl -o /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-6.repo

rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7