RHL替换CentOS yum方法详解

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，会提示如下错误：
[root@vpser ~]# yum install libjpeg libjpeg-devel
Loaded plugins: rhnplugin, security
This system is not registered with RHN.
RHN support will be disabled.
Setting up Install Process
No package libjpeg-devel available.
Nothing to do

解决方法：
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  或  找对应系统版本号
如系统是5.5 64位，则打开 找到yum 、yum-fastestmirror、yum-metadata-parser 这3个软件包的地址，然后执行：一下下载地址可能会无法下载，到上面网址找对应的下载文件！
wget
wget
wget

下载下这3个软件包，再执行：
rpm -ivh yum-*
再执行：（如果是6.*的版本，则将下面内容里面的5改成6后再执行。）
cat >/etc/yum.repos.d/CentOS-Base.repo<
[base]
name=CentOS-$releasever - Base
baseurl=
#mirrorlist=
gpgcheck=1
gpgkey=

#released updates 
[updates]
name=CentOS-$releasever - Updates
baseurl=
#mirrorlist=
gpgcheck=1
gpgkey=

#packages used/produced in the build but not released
[addons]
name=CentOS-$releasever - Addons
baseurl=
#mirrorlist=
gpgcheck=1
gpgkey=

#additional packages that may be useful
[extras]
name=CentOS-$releasever - Extras
baseurl=
#mirrorlist=
gpgcheck=1
gpgkey=

#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-$releasever - Plus
baseurl=
#mirrorlist=
gpgcheck=1
enabled=0
gpgkey=

#contrib - packages by Centos Users
[contrib]
name=CentOS-$releasever - Contrib
baseurl=
#mirrorlist=
gpgcheck=1
enabled=0
gpgkey=
eof

再执行：yum makecache 生成缓存，再yum install 安装软件试试