最近博主在学习Linux，菜鸟级别的的选手连装个Chrome都觉得难，悲了个催的……百度了很多教程，大多是类似的。博主的配置是在VM8下搭建的RHEL5.3 (Tikanga)版本，不知道什么原因，每次在输入yum install google-chrome-stable之后就会出现“This system is not registered with RHN”的错误提示，蛋疼不已。百度无果后，GG大神帮上忙了（搜索Redhat This system is not registered with RHN，会冒出很多国外大牛的文章）。出现这个错误的原因是你的Linux木有花钱在红帽网络上注册^^，所以无法下载谷歌Chrome的软件包，解决方案可以使用从Redhat演化而来的免费Linux版本CentOS，通过CentOS的yum更新源来实现RHEL5的YUM功能。下面博主结合GG到的国外文章谈谈How to Install CentOS YUM on Redhat Linux RHEL5，以此来解决This system is not registered with RHN的问题。
1 check what yum package installed
查看RHEL是否安装了yum，若是安装了，那么又有哪些yum包：
[root@localhost ~]# rpm -qa |grep yum
yum-metadata-parser-1.0-8.fc6
yum-3.0.1-5.el5
yum-rhn-plugin-0.4.3-1.el5
yum-updatesd-3.0.1-5.el5
2 remove all installed yum packages
卸载上面显示的所有yum包：
[root@localhost ~]# rpm -qa|grep yum|xargs rpm -e --nodeps（不检查依赖，直接删除rpm包）
再用
[root@localhost ~]# rpm -qa |grep yum
[root@localhost ~]#
查看，无信息显示表示已经卸载完成。
3 download the centos packages from website
下载 CentOS YUM包，首先我们需要找到CentOS YUM的更新源，推荐的有（前三个适用于Redhat Linux5版本，最后一个适用于RHEL6的64位版本，当然不管是RHEL5还是RHEL6等等都可以从下面四个镜像网站中下载）：
1.国外镜像源http://ftp.heanet.ie/pub/centos/5/os/i386/CentOS/
2.中国科技大学http://centos.ustc.edu.cn/centos/5/os/i386/CentOS/
3.网易开源镜像http://mirrors.163.com/centos/5/os/i386/CentOS/
4.搜狐开源镜像http://mirrors.ustc.edu.cn/centos/6/os/x86_64/Packages/
接着我们就需要在终端里面输入以下命令进行下载（以博主的RHEL5.3为例，从中国科大下载镜像，下载的目录如果没设置的话就会默认是[root@localhost ~]# pwd显示的路径）
[root@localhost ~]# wget http://centos.ustc.edu.cn/centos/5/os/i386/CentOS/yum-fastestmirror-1.1.16-21.el5.centos.noarch.rpm
[root@localhost ~]# wget http://centos.ustc.edu.cn/centos/5/os/i386/CentOS/yum-metadata-parser-1.1.2-4.el5.i386.rpm
[root@localhost ~]# wget http://centos.ustc.edu.cn/centos/5/os/i386/CentOS/yum-3.2.22-40.el5.centos.noarch.rpm
[root@localhost ~]# wget http://centos.ustc.edu.cn/centos/5/os/i386/CentOS/python-iniparse-0.2.3-6.el5.noarch.rpm
如果是Redhat 64位系统，按如下进行下载：
[root@localhost ~]# wget http://centos.ustc.edu.cn/centos/5/os/x86_64/CentOS/yum-fastestmirror-1.1.16-21.el5.centos.noarch.rpm
[root@localhost ~]# wget http://centos.ustc.edu.cn/centos/5/os/x86_64/CentOS/yum-metadata-parser-1.1.2-4.el5.x86_64.rpm
4 安装这所下载的四个包
注意:单个的安装包可能会依赖其它包（例如yum和yum-fastestmirror会相互依赖），所以我们可以把所有这些包放在一起，用一行命令将它们同时安装即可：
[root@localhost ~]# rpm -ivh yum-fastestmirror-1.1.16-21.el5.centos.noarch.rpm yum-metadata-parser-1.1.2-4.el5.i386.rpm yum-3.2.22-40.el5.centos.noarch.rpm
对应Redhat 64位系统的操作如下：
[root@localhost ~]# rpm -ivh yum-fastestmirror-1.1.16-21.el5.centos.noarch.rpm yum-metadata-parser-1.1.2-4.el5.x86_64.rpm yum-3.2.22-40.el5.centos.noarch.rpm
5 download configure file
下载CentOS-Base.repo到/etc/yum.repos.d/文件夹里： [root@localhost ~]# wget http://docs.linuxtone.org/soft/lemp/CentOS-Base.repo
-O /etc/yum.repos.d/CentOS-Base.repo
[root@localhost ~]# wget http://huangkeye-blog.googlecode.com/files/CentOS-Base.repo
-O /etc/yum.repos.d/CentOS-Base.repo（以上这两个适用于RHEL版本5）
[root@localhost ~]# wget http://my-project-huangkeye.googlecode.com/files/CentOS-Base.repo
-O /etc/yum.repos.d/CentOS-Base.repo（这个适用于RHEL版本6) 也可以直接进入vim修改该文件为以下内容：
[base]
name=CentOS-5 - Base
baseurl=http://centos.ustc.edu.cn/centos/5/os/$basearch/
gpgcheck=1
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5
#released updates
[update]
name=CentOS-5 - Updates
baseurl=http://centos.ustc.edu.cn/centos/5/updates/$basearch/
gpgcheck=1
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5
#packages used/produced in the build but not released
[addons]
name=CentOS-5 - Addons
baseurl=http://centos.ustc.edu.cn/centos/5/addons/$basearch/
gpgcheck=1
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5
#additional packages that may be useful
[extras]
也可以直接进入vim修改该文件为以下内容：
[base]
name=CentOS-5 - Base
baseurl=http://centos.ustc.edu.cn/centos/5/os/$basearch/
gpgcheck=1
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5
#released updates
[update]
name=CentOS-5 - Updates
baseurl=http://centos.ustc.edu.cn/centos/5/updates/$basearch/
gpgcheck=1
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5
#packages used/produced in the build but not released
[addons]
name=CentOS-5 - Addons
baseurl=http://centos.ustc.edu.cn/centos/5/addons/$basearch/
gpgcheck=1
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5
#additional packages that may be useful
[extras]
gpgcheck=1
enabled=0
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5
#packages in testing
[testing]
name=CentOS-5 - Testing
baseurl=http://centos.ustc.edu.cn/centos/5/testing/$basearch/
gpgcheck=1
enabled=0
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5
6 [选做]clear cache and rebuild
需要清除和重建cache：
[root@localhost ~]# yum clean metadata
Loaded plugins: fastestmirror
0 metadata files removed
0 sqlite files removed
0 metadata files removed
[root@localhost ~]# yum clean dbcache
Loaded plugins: fastestmirror
0 sqlite files removed
[root@localhost ~]# yum makecache
Loaded plugins: fastestmirror
Determining fastest mirrors
addons | 1.9 kB 00:00
addons/filelists_db | 568 B 00:00 addons/other_db | 546 B 00:00
addons/primary_db | 1.1 kB 00:00
base | 1.1 kB 00:00
base/filelists | 3.6 MB 00:03 base/other | 13 MB 00:13
base/group | 1.1 MB 00:02
base/primary | 1.2 MB 00:01
extras | 2.1 kB 00:00
extras/filelists_db | 241 kB 00:00
extras/other_db | 406 kB 00:00
extras/group | 9.7 kB 00:00
extras/primary_db | 188 kB 00:00
update | 1.9 kB 00:00 update/filelists_db | 3.1 MB 00:03
update/other_db | 15 MB 00:15
update/primary_db | 634 kB 00:00
base 3641/3641
base 3641/3641
base 3641/3641
Metadata Cache Created
[root@localhost ~]#
7 installation has been completed, testing
//安装成功，开始测试：
[root@localhost ~]# yum update
出处：http://www.seacha.com/article.php/knowledge/linux/linuxbase/2013/0925/2216.html