CentOS更换yum源

转到源目录：cd /etc/yum.repos.d/
备份原来的源：mv CentOS-Base.repo CentOS-Base.repo.backup
下载源：

//163源
wget http://mirrors.163.com/.help/CentOS7-Base-163.repo
//阿里源
wget http://mirrors.aliyun.com/repo/Centos-7.repo

重命名：mv Centos-7.repo CentOS-Base.repo
运行以下命令生成缓存：

yum clean all

yum makecache

yum update