Centos7更改yum源

1.进入目录

cd /etc/yum.repos.d/

2.备份

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

3.下载想要的源

#下载阿里云的源
wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo

4.清楚旧缓存数据，建立新的缓存

yum clean all
yum makecache