1.更改yum源配置
mv /etc/yum.repos.d/centos7.repo /etc/yum.repos.d/centos7.repo.bak
curl -o /etc/yum.repos.d/centos7.repo http://mirrors.aliyun.com/repo/Centos-7.repo
2.清除yum缓存
yum clean all
3. 更新
yum update
4. 重启
reboot
现在你就可以查看到你更新的最新系统版本了：
>>cat /etc/redhat-release
CentOS Linux release 7.6.1810 (Core)
so easy...