## centos中阿里云yum源配置
1.首先备份系统自带yum源配置文件/etc/yum.repos.d/CentOS-Base.repo
mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup
2.下载ailiyun的yum源配置文件到/etc/yum.repos.d/
wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo
如果没联网的话，需要宿主机下载该文件复制到上述目录
3、运行yum makecache生成缓存
yum makecache
4、这时候再更新系统就会看到以下mirrors.aliyun.com信息
yum update -y