由于Redhat的yum在线更新是收费的，如果没有注册的话是不能使用的，即不能在线安装软件。我们可以借助于centos系统开源包来给我们的yum工具做相应配置就可以使用了。
1、删除redhat原有的yum源
#rpm -aq | grep yum|xargs rpm -e --nodeps
2、下载新的yum安装包
这里我们使用CentOS的yum源
从网络下载一个文件并保存在当前目录
#wgethttp://mirror.centos.org/centos/6.5/os/i386/Packages/python-iniparse-0.3.1-2.1.el6.noarch.rpm
#wget http://mirror.centos.org/centos/6.5/os/i386/Packages/yum-metadata-parser-1.1.2-16.el6.i686.rpm
#wget http://mirror.centos.org/centos/6.5/os/i386/Packages/yum-3.2.29-40.el6.centos.noarch.rpm
#wget http://mirror.centos.org/centos/6.5/os/i386/Packages/yum-plugin-fastestmirror-1.1.30-14.el6.noarch.rpm
3、安装yum软件包
#rpm -ivh python-iniparse-0.3.1-2.1.el6.noarch.rpm
#rpm -ivh yum-metadata-parser-1.1.2-14.1.el6.i686.rpm
#rpm -ivh yum-3.2.27-14.el6.centos.noarch.rpm yum-plugin-fastestmirror-1.1.26-11.el6.noarch.rpm
注意：最后两个安装包要放在一起同时安装，否则会提示相互依赖，安装失败。
4、更改yum源 #我们使用网易的CentOS镜像源
#cd /etc/yum.repos.d/
#wget http://mirrors.163.com/.help/CentOS6-Base-163.repo
#vi CentOS6-Base-163.repo
编辑文件，把文件里面的$releasever全部替换为版本号，即6 最后保存！或者直接把下面的内存拷贝到CentOS6-Base-163.repo文件中即可（已经修改好）
:%s/$releasever/6/g
#########################################################################
#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 CentOSupdates
#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
#releasedupdates
[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
#additionalpackages 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
#additionalpackages 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
#########################################################################
5、清理yum缓存
#yum clean all
#yum makecache #将服务器上的软件包信息缓存到本地,以提高搜索安装软件的速度
#yum install vim* #测试域名是否可用
至此，Redhat6可以使用CentOS的yum源在线安装软件了！
本地yum源配置
1、挂载iso文件
#mount -t iso9660 /dev/cdrom /mnt/iso/
注：也可自己创建个目录把光盘上的rpm包cp到自己建的目录下。关于createrepo -p 自己建的目录,然后ls *repo*查看该目录下生成的文件，createrepo --update 自己建的目录（如果有新rpm包扔进来需要更新）。前提是需要一个工具createrepo，使用yum安装：yum -y install createrepo，此为场外话
2、修改yum配置文件
#vi /etc/yum.repo.d/iso
===============
[base]
name=locale
baseurl=file:///mnt/iso/Server
enabled=1 ---开启本地更新模式
gpgcheck=1
===============
redhat-6
====================================
[Server]
name=Server
baseurl=file:///mnt/cdrom/Server
enabled=1
gpgcheck=0
[HighAvailability]
name=HighAvailability
baseurl=file:///mnt/cdrom/HighAvailability
enabled=1
gpgcheck=0
[LoadBalancer]
name=LoadBalancer
baseurl=file:///mnt/cdrom/LoadBalancer
enabled=1
gpgcheck=0
[LoadBalancer]
name=LoadBalancer
baseurl=file:///mnt/cdrom/LoadBalancer
enabled=1
gpgcheck=0
3、清理缓存
#yum clean all
yum安装rpm包时遇到“warning: rpmts_HdrFromFdno:Header V3 DSA signature: NOKEY”的解决办法
在Redhat Linux下用yum安装rpm时有时候会出现下面错误导致安装失败
warning: rpmts_HdrFromFdno: Header V3 DSA signature: NOKEY, key ID*****
这是由于yum安装了旧版本的GPG keys造成的，解决办法是可以运行下面命令：
$ sudo rpm --import /etc/pki/rpm-gpg/RPM*
以上就是yum相关的知识，还有yum的命令详解如下：yum命令详解
