centos7 修改yum源为阿里源

cd /etc/yum.repos.d

sudo mv CentOS-Base.repo CentOS-Base.repo.bak

sudo wget -O CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo

sudo wget -P /etc/yum.repos.d/ http://mirrors.aliyun.com/repo/epel-7.repo 

yum clean all

yum makecache

 其中第四行为了添加阿里EPEL源，可选