1、安装wget，如果安装了就无需安装 ``` yum install -y wget ``` 2、备份原yum源 ``` mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup ``` 3、下载阿里云的CentOS-Base.repo 到/etc/yum.repos.d/ ``` wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo ``` 4、清理缓存 ``` yum clean all ``` 5、生成新的缓存 ``` yum makecache ``` 6、更新yum ``` yum -y update ```