1.安装yum优先级插件
yum install yum-priorities
2.epel简介: https://fedoraproject.org/wiki/EPEL/zh-cn
rpm -Uvh http://mirrors.ustc.edu.cn/fedora/epel/6/x86_64/epel-release-6-8.noarch.rpm
rpm -Uvh http://rpms.famillecollet.com/enterprise/remi-release-6.rpm

3.查看是否安装成功
rpm -q epel-release
 4.导入key：
rpm --import /etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-6
5.修改/etc/yum.repos.d/epel.repo文件
在[epel]最后添加一条属性 priority=11
vi /etc/yum.repos.d/epel.repo
意思是yum先去官方源查，官方没有再去epel的源找
6.重建缓存
yum makecache