centos7 指向阿里yum源

备份系统自带的yum源配置文件

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

下载阿里云的yum源配置

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

更新现有镜像源

清除缓存：

yum clean all 

生成缓存

yum makecache

查看有多包

yum repolist