一 背景
RHEL以及他的衍生发行版如CentOS、Scientific Linux为了稳定，官方的rpm repository提供的rpm包往往是很滞后的，而EPEL恰恰可以解决这两方面的问题。EPEL的全称叫Extra Packages for Enterprise Linux 。EPEL是由Fedora 社区打造，为RHEL 及衍生发行版如CentOS、Scientific Linux 等提供高质量软件包的项目。装上了EPEL之后，就相当于添加了一个第三方源。在某些情况下，通过EPEL repo 安装一些软件比其他安装方式方便很多。
 
二 操作步骤
2.1 执行安装命令
yum -y install epel-release
2.2 查看结果
yum repolist
Loaded plugins: fastestmirror, ovl
Loading mirror speeds from cached hostfile
 * base: ap.stykers.moe
 * epel: mirror01.idc.hinet.net
 * extras: mirrors.cn99.com
 * updates: mirrors.njupt.edu.cn
repo id                                                             repo name                                                                                         status
base/7/x86_64                                                        CentOS-7 - Base                                                                                   10019
*epel/x86_64                                                       Extra Packages for Enterprise Linux 7 - x86_64                                                      12973
extras/7/x86_64                                                     CentOS-7 - Extras                                                                                   371
updates/7/x86_64                                                    CentOS-7 - Updates                                                                                 1163
repolist: 24526
 
我们可以与安装之前对比一下：
yum repolist
Loaded plugins: fastestmirror, ovl
Loading mirror speeds from cached hostfile
 * base: mirrors.nwsuaf.edu.cn
 * extras: mirrors.nwsuaf.edu.cn
 * updates: mirrors.nwsuaf.edu.cn
repo id                                                                           repo name                                                                           status
base/7/x86_64                                                                     CentOS-7 - Base                                                                     10019
extras/7/x86_64                                                                   CentOS-7 - Extras                                                                     371
updates/7/x86_64                                                                 CentOS-7 - Updates                                                                    1163
repolist: 11553
效果不言而喻。
 
2.3 其他安装方式
通过rpm 包可以安装，下载地址如下：https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm;