备份原有的CentOS-Base.repo备份为CentOS-Base.repo.bak

进入cd /etc/yum.repos.d

mv CentOS-Base.repo CentOS-Base.repo.bak

删除文件 CentOS-Base.repo

wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.163.com/.help/CentOS7-Base-163.repo

yum clean all

yum makecache
————————————————