mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup
 
rm -f /etc/yum.repos.d/*.repo
 
curl -o /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo
 
# 4. 清理YUM缓存并生成新的缓存
sudo yum clean all
sudo yum makecache