错误：为仓库 'appstream' 下载元数据失败 : Cannot prepare internal mirrorlist: No URLs in mirrorlist

sudo sed -i -e "s|mirrorlist=|#mirrorlist=|g" /etc/yum.repos.d/CentOS-*
sudo sed -i -e "s|#baseurl=http://mirror.centos.org|baseurl=http://vault.centos.org|g" /etc/yum.repos.d/CentOS-*

执行以上两条代码