Centos7更换阿里源

1. 更换源之前，请确保Centos7 已经连上网

cd /etc 

cd /etc/yum.repos.d/

mv CentOS-Base.repo CentOS-Base.repo.back  #建议备份或者改名

wget -O CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo 

yum makecache #生成缓存