Centos7配置更新国内yum源

163 源网站：http://mirrors.163.com/.help/centos.html

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

网易163源：
wget http://mirrors.163.com/.help/CentOS7-Base-163.repo
yum -y install epel-release
yum clean all
yum makecache

阿里云源：
wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo
yum -y install epel-release
yum clean all
yum makecache

epel源：
yum -y install epel-release
yum clean all
yum makecache