解决rhel相关系统下yum找不到安装包的解决方法

最近重新安装了Linux，用的版本是CentOS 5.1。但老是出现很多包找不到的情况。

[root@toughhou /]# yum install rlwrap
Loaded plugins: fastestmirror, rhnplugin, security
This system is not registered with RHN.
RHN support will be disabled.
Loading mirror speeds from cached hostfile
 * rpmforge: ftp.kddilabs.jp
Setting up Install Process
No package rlwrap available.
Nothing to do

后来才发现对于RHEL及相关发行版本，epel源非常好用。

epel(Extral Package for Enterprise Linux)是fedora社区支撑的为RHEL及衍生发行版本如CentOS, Fedora等提供的高质量软件包的项目。

[root@toughhou /]# rpm -Uvh http://mirrors.sohu.com/fedora-epel/5/i386/epel-release-5-4.noarch.rpm

若是CentOS6 的话，用下面这个。

http://mirrors.ustc.edu.cn/epel/6/x86_64/epel-release-6-8.noarch.rpm

[root@toughhou /]# yum install rlwrap
Loaded plugins: fastestmirror, rhnplugin, security
This system is not registered with RHN.
RHN support will be disabled.
Loading mirror speeds from cached hostfile
 * epel: mirrors.hust.edu.cn
 * rpmforge: ftp.kddilabs.jp
epel                                                                    | 3.6 kB     00:00     
epel/primary_db                                                         | 3.1 MB     00:28     
Setting up Install Process
Resolving Dependencies
--> Running transaction check
---> Package rlwrap.i386 0:0.37-1.el5 set to be updated
--> Finished Dependency Resolution

Dependencies Resolved

===============================================================================================
 Package               Arch                Version                   Repository           Size
===============================================================================================
Installing:
 rlwrap                i386                0.37-1.el5                epel                 91 k

Transaction Summary
===============================================================================================
Install       1 Package(s)
Upgrade       0 Package(s)

Total download size: 91 k
Is this ok [y/N]: y
Downloading Packages:
rlwrap-0.37-1.el5.i386.rpm                                              |  91 kB     00:00     
warning: rpmts_HdrFromFdno: Header V3 DSA signature: NOKEY, key ID 217521f6
epel/gpgkey                                                             | 1.7 kB     00:00     
Importing GPG key 0x217521F6 "Fedora EPEL <epel@fedoraproject.org>" from /etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL
Is this ok [y/N]: y
Running rpm_check_debug
Running Transaction Test
Finished Transaction Test
Transaction Test Succeeded
Running Transaction
  Installing     : rlwrap                                                                  1/1

Installed:
  rlwrap.i386 0:0.37-1.el5

Complete!

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