阿里源

环境：centos7  通外网

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

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

yum clean all # 清除系统所有的yum缓存
yum makecache # 生成yum缓存

 

所有的源：yum repolist all

查看可有yum源：yum repolist enable