cd /etc/yum.repos.d
备份一下原来的yum源
mv CentOS-Base.repo CentOS-Base.repo.bk
下载新的CentOS-Base.repo 到/etc/yum.repos.d/ 如下的源用一个就好，三条命令选其一
//更新为阿里云的源 wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-6.repo //更新为163的源 wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.163.com/.help/CentOS6-Base-163.repo //更新为搜狐的源 wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.sohu.com/help/CentOS-Base-sohu.repo
运行yum makecache生成缓存
yum clean all
yum makecache
原文：https://www.cnblogs.com/laoyeye/p/12193791.html