ruiy哥,抛砖引玉
当你使用rhel系统时,[大部分数据库中心及政府企业选择linux服务器时通常考虑采购的版本一般不外乎是Rhel红帽及Suse,理由你懂的EcoSystem!]
你没有一个红帽网络公司订阅,你是没法使用Rhel上的yum功能,yum是红帽Linux在线更新安装软件的工具，前面提到的红帽网络订阅即RHN是一项收费的服务项目。
一般无RHN订阅,使用yum时没法用报如下错误
This system is not registered with RHN.
RHN support will be disabled.
由于CentOS是从Redhat演化而来的免费Linux版本，因此可以利用CentOS的yum更新源来实现RHEL5的YUM功能：
具体步骤如下:
1.清除Rhel默认yum缓存,
yum clean all
2.移除默认yum
rpm -qa|grep yum|xargs rpm -e --nodeps
3.安装包下载
所有需下载的安装包如截图
wget http://mirrors.cat.pdx.edu/centos/5/os/x86_64/CentOS/centos-release-notes-5.9-0.x86_64.rpm
wget http://mirrors.cat.pdx.edu/centos/5/os/x86_64/CentOS/yum-3.2.22-40.el5.centos.noarch.rpm
wget http://mirrors.cat.pdx.edu/centos/5/os/x86_64/CentOS/yum-updatesd-0.9-5.el5.noarch.rpm
wget http://mirrors.cat.pdx.edu/centos/5/os/x86_64/CentOS/centos-release-5-10.el5.centos.x86_64.rpm
wget http://mirrors.cat.pdx.edu/centos/5/os/x86_64/CentOS/centos-release-notes-5.10-0.x86_64.rpm
wget http://mirrors.cat.pdx.edu/centos/5/os/x86_64/CentOS/yum-fastestmirror-1.1.16-21.el5.centos.noarch.rpm
wget http://mirrors.cat.pdx.edu/centos/5/os/x86_64/CentOS/yum-metadata-parser-1.1.2-4.el5.x86_64.rpm
4.Import the new KEY:
rpm --import RPM-GPG-KEY-CentOS-5
5.Remove the redhat release
rpm -e --nodeps redhat-release
6.尝试删除Redhat Network plugin-RHN
rpm -e yum-rhn-plugin
7.安装以下载的包
rpm -Uvh --force yum*.rpm centos*.rpm
