CentOS7 yum被删了，恢复
1、前往国内网易或阿里下载镜像。wget https://mirrors.aliyun.com/centos/7.8.2003/os/x86_64/Packages/yum-metadata-parser-1.1.4-10.el7.x86_64.rpmwget https://mirrors.aliyun.com/centos/7.8.2003/os/x86_64/Packages/yum-3.4.3-167.el7.centos.noarch.rpmwget https://mirrors.
