步骤一:安装wget
yum -y install wget
步骤二:安装阿里镜像源
wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo
步骤三:运行yum makecache生成缓存
yum makecache
步骤四:更新新yum
yum -y update