安装wget

yum -y install wget

备份Centos7自带的镜像源文件

mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo_back

下载镜像源文件

wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo

下载镜像源文件

 wget -O /etc/yum.repos.d/epel-7.repo http://mirrors.aliyun.com/repo/epel-7.repo

清除缓存

yum clean all

生成缓存

yum makecache

更新yum

yum update

查看系统可用的yum源和所有的yum源

yum repolist enabled
yum repolist all

脚本

#!/bin/bash
yum -y install wget
mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo_back
wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo
wget -O /etc/yum.repos.d/epel-7.repo http://mirrors.aliyun.com/repo/epel-7.repo
yum clean all
yum makecache
yum update -y
yum repolist enabled
yum repolist all