问题：使用 Red Hat Enterprise Linux Server(RHEL) yum安装软件时显示 This system is not registered with RHN. RHN support will be disabled. 

原因：

Red Hat Enterprise Linux Server(RHEL) 的yum服务是付费的，因为没有付费，所以无法使用yum安装软件，如RHEL想安装YUM，一种可行的办法是移植使用CentOS的YUM。

解决方法：

步骤一：卸载RHEL的yum，并下载CentOS的对应软件包

执行：rpm -qa|grep yum|xargs rpm -e --nodeps  将yum卸载掉

cat /etc/issue && uname -a 看一下系统版本号和系统位数

到 http://mirrors.kernel.org/centos/ 或 http://mirrors.163.com/centos/ 找对应系统版本号

如果系统是5.* 64位，则打开http://mirrors.kernel.org/centos/5/os/x86_64/CentOS/
如果系统是5.* 32位，则打开http://mirrors.kernel.org/centos/5/os/i386/CentOS/
如果系统是6.* 64位：http://mirrors.kernel.org/centos/6/os/x86_64/Packages/
如果系统是6.* 32位：http://mirrors.kernel.org/centos/6/os/i386/Packages/

下载的文件包括：

python-iniparse-0.3.1-2.1.el6.noarch.rpm

python-urlgrabber-3.9.1-11.el6.noarch.rpm

yum-3.2.29-73.el6.centos.noarch.rpm

yum-metadata-parser-1.1.2-16.el6.i686.rpm

yum-plugin-fastestmirror-1.1.30-37.el6.noarch.rpm

步骤二：安装CentOS的对应软件包

安装步骤：

rpm -ivh python-iniparse-0.3.1-2.1.el6.noarch.rpm

rpm -ivh yum-metadata-parser-1.1.2-16.el6.x86_64.rpm 

rpm -ivh python-urlgrabber-3.9.1-11.el6.noarch.rpm 

这一步可能出如下错误

warning: python-urlgrabber-3.9.1-11.el6.noarch.rpm: Header V3 RSA/SHA1 Signature, key ID c105b9de: NOKEY

Preparing...                ########################################### [100%]

file /usr/lib/python2.6/site-packages/urlgrabber/grabber.py from install of python-urlgrabber-3.9.1-11.el6.noarch conflicts with file from package python-urlgrabber-3.9.1-8.el6.noarch

file /usr/lib/python2.6/site-packages/urlgrabber/grabber.pyc from install of python-urlgrabber-3.9.1-11.el6.noarch conflicts with file from package python-urlgrabber-3.9.1-8.el6.noarch

file /usr/lib/python2.6/site-packages/urlgrabber/grabber.pyo from install of python-urlgrabber-3.9.1-11.el6.noarch conflicts with file from package python-urlgrabber-3.9.1-8.el6.noarch

file /usr/lib/python2.6/site-packages/urlgrabber/progress.pyc from install of python-urlgrabber-3.9.1-11.el6.noarch conflicts with file from package python-urlgrabber-3.9.1-8.el6.noarch

file /usr/lib/python2.6/site-packages/urlgrabber/progress.pyo from install of python-urlgrabber-3.9.1-11.el6.noarch conflicts with file from package python-urlgrabber-3.9.1-8.el6.noarch

原因是包冲突，需要卸载原有的urlgrabber包：

[root@rchen98]# rpm -qa |grep urlgrabber

python-urlgrabber-3.9.1-8.el6.noarch

[root@rchen98]# rpm -e python-urlgrabber-3.9.1-8.el6.noarch

然后再安装。

然后安装yum

rpm -ivh yum-3.2.29-73.el6.centos.noarch.rpm  yum-plugin-fastestmirror-1.1.30-37.el6.noarch.rpm 

步骤三：生成yum.repos.d文件

到http://mirrors.163.com的 centos帮助文档 中下载CentOS6-Base-163.repo文件，存放到/etc/yum.repos.d中

#wget http://mirrors.163.com/.help/CentOS6-Base-163.repo

改名为：CentOS6-Base.repo

然后把文件里的$releasever都改为你的Linux版本（6或者5），也就是文件修改成如下即可：

# CentOS-Base.repo

#

# The mirror system uses the connecting IP address of the client and the

# update status of each mirror to pick mirrors that are updated to and

# geographically close to the client.  You should use this for CentOS updates

# unless you are manually picking other mirrors.

#

# If the mirrorlist= does not work for you, as a fall back you can try the

# remarked out baseurl= line instead.

#

#

[base]

name=CentOS-6 - Base - 163.com

baseurl=http://mirrors.163.com/centos/6/os/$basearch/

#mirrorlist=http://mirrorlist.centos.org/?release=6&arch=$basearch&repo=os

gpgcheck=1

gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-6

#released updates

[updates]

name=CentOS-6 - Updates - 163.com

baseurl=http://mirrors.163.com/centos/6/updates/$basearch/

#mirrorlist=http://mirrorlist.centos.org/?release=6&arch=$basearch&repo=updates

gpgcheck=1

gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-6

#additional packages that may be useful

[extras]

name=CentOS-6 - Extras - 163.com

baseurl=http://mirrors.163.com/centos/6/extras/$basearch/

#mirrorlist=http://mirrorlist.centos.org/?release=6&arch=$basearch&repo=extras

gpgcheck=1

gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-6

#additional packages that extend functionality of existing packages

[centosplus]

name=CentOS-6 - Plus - 163.com

baseurl=http://mirrors.163.com/centos/6/centosplus/$basearch/

#mirrorlist=http://mirrorlist.centos.org/?release=6&arch=$basearch&repo=centosplus

gpgcheck=1

enabled=0

gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-6

#contrib - packages by Centos Users

[contrib]

name=CentOS-6 - Contrib - 163.com

baseurl=http://mirrors.163.com/centos/6/contrib/$basearch/

#mirrorlist=http://mirrorlist.centos.org/?release=6&arch=$basearch&repo=contrib

gpgcheck=1

enabled=0

gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-6

步骤四：重建缓存

yum clean all 清除原有缓存

yum makecache  获取yum列表

等待，大约三分钟后出现下面提示，表示yum更改完成：

Metadata Cache Created

RHEL6.5 移植使用CentOS 的YUM 步骤