超简单更新CentOS7配置yum源

1.打开centos的yum文件夹

cd /etc/yum.repos.d/

2.安装wget

yum -y install wget

3.用wget下载repo文件，选择下面其中一个即可

wget http://mirrors.aliyun.com/repo/Centos-7.repo
wget http://mirrors.163.com/.help/CentOS7-Base-163.repo
wget http://mirrors.163.com/.help/CentOS6-Base-163.repo
wget http://mirrors.163.com/.help/CentOS5-Base-163.repo

4.备份系统原来的repo文件

当前目录是/etc/yum.repos.d/，刚刚下载的Centos-7.repo也在这个目录上

mv CentOS-Base.repo CentOS-Base.repo.bak

5.替换系统原理的repo文件

mv Centos-7.repo CentOS-Base.repo

6.执行yum源更新命令

yum clean all
yum makecache
yum update