在Centos 5.x或6.x上安装RHEL EPEL Repo

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