$yum install -y wget
#备份
mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup
#下载新的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
#清除YUM缓存
$yum clean all
#重建数据库
$rpm --rebuilddb
#生成缓存
$yum makecache
2017-11-16 Boy