1.优化镜像自带的yum源为国内源

#!/bin/bash
#创建一个备份yum源的文件夹
mkdir /etc/yum.repos.d/backup/
#将原有yum源备份到创建的备份文件夹
mv /etc/yum.repos.d/*.repo /etc/yum.repos.d/backup/
#第一种情况：CentOS版本为6时，替换为CentOS6对应的yum源
if [ `uname -r |awk -F. ‘{ print $1 }‘` -eq 2 ];then
    curl -o /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-6.repo
    curl -o /etc/yum.repos.d/epel.repo http://mirrors.aliyun.com/repo/epel-6.repo
    yum makecache
fi
#第二种情况：当系统为CentOS7时，替换yum源为CentOS7的yum源
if [ `uname -r |awk -F. ‘{ print $1 }‘` -eq 3 ];then
    curl -o /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo
    curl -o /etc/yum.repos.d/epel.repo http://mirrors.aliyun.com/repo/epel-7.repo
    yum makecache
fi