repository，资源库，源的意思。RHEL EPEL(Extra Packages for Enterprise Linux) Repo是Linux发行版中最大的软件仓库之一，免费，丰富的软件包更新。
安装步骤
Centos 5.x
wget http://dl.fedoraproject.org/pub/epel/5/x86_64/epel-release-5-4.noarch.rpm
wget http://rpms.famillecollet.com/enterprise/remi-release-5.rpm
rpm -ivh epel-release-5-4.noarch.rpm
rpm -ivh remi-release-5.rpm
Centos 6.x
wget http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm
wget http://rpms.famillecollet.com/enterprise/remi-release-6.rpm
rpm -ivh epel-release-6-8.noarch.rpm
rpm -ivh remi-release-6.rpm
完成后的设置
ls -1 /etc/yum.repos.d/epel* /etc/yum.repos.d/remi.repo
返回
/etc/yum.repos.d/epel.repo
/etc/yum.repos.d/epel-testing.repo
/etc/yum.repos.d/remi.repo
允许remi repository
vi /etc/yum.repos.d/remi.repo
编辑[remi]下的enabled选项从0设为1
[remi]
name=Les RPM de remi pour Enterprise Linux 6 - $basearch
#baseurl=http://rpms.famillecollet.com/enterprise/6/remi/$basearch/
mirrorlist=http://rpms.famillecollet.com/enterprise/6/remi/mirror
enabled=1
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-remi
至此，安装完成。
安装完运行yum报错：
Error: Cannot retrieve metalink for repository: epel. Please verify its path and try again
解决办法：
vi /etc/yum.repos.d/epel.repo
编辑[epel]下的baseurl前的#号去掉，mirrorlist前添加#号。正确配置如下：
[epel]
name=Extra Packages for Enterprise Linux 6 - $basearch
baseurl=http://download.fedoraproject.org/pub/epel/6/$basearch
#mirrorlist=https://mirrors.fedoraproject.org/metalink?repo=epel-6&arch=$basearch
failovermethod=priority
enabled=1
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-6
再运行
yum makecache