先看系统版本：
因为redhat的yum没有注册，所以需要卸载已经安装的yum
#rpm -qa|grep yum
有一个算一个都卸载了
2.下载yum包：
#wget http://yum.baseurl.org/download/2.0/yum-2.0.8-1.src.rpm
3.安装
#rpmbuild --rebuild yum-2.0.8-1.src.rpm
日志输入如下：
Requires(post): /bin/sh
Requires(preun): /bin/sh
Requires: /bin/bash /bin/sh /usr/bin/python config(yum) = 2.0.8-1
libxml2-python python rpm >= 0:4.1.1 rpm-python
Obsoletes: yum-phoebe
Checking for unpackaged file(s): /usr/lib/rpm/check-files /var/tmp/yum-
2.0.8root
Wrote: /usr/src/redhat/RPMS/noarch/yum-2.0.8-1.noarch.rpm
Executing(%clean): /bin/sh -e /var/tmp/rpm-tmp.40887
+ umask 022
+ cd /usr/src/redhat/BUILD
+ cd yum-2.0.8
+ ‘[’ /var/tmp/yum-2.0.8root ’!=’ / ’]‘
+ rm -rf /var/tmp/yum-2.0.8root
+ exit 0
Executing(–clean): /bin/sh -e /var/tmp/rpm-tmp.40887
+ umask 022
+ cd /usr/src/redhat/BUILD
+ rm -rf yum-2.0.8
+ exit 0
进入到:/usr/src/redhat/RPMS/noarch/
# cd /usr/src/redhat/RPMS/noarch/
# rpm -ivh yum-2.0.8-1.noarch.rpm
4.配置yum源
编辑/etc/yum.conf，去除红框内容
取而代之写入下面内容：
[base]
name=CentOS-$releasever - Base
baseurl=http://ftp.riken.jp/Linux/centos/4.8/os/$basearch/
gpgcheck=1
#released updates
[update]
name=CentOS-$releasever - Updates
baseurl=http://ftp.riken.jp/Linux/centos/4.8/updates/$basearch/
gpgcheck=1
#packages used/produced in the build but not released
[addons]
name=CentOS-$releasever - Addons
baseurl=http://ftp.riken.jp/Linux/centos/4.8/addons/$basearch/
gpgcheck=1
#additional packages that may be useful
[extras]
name=CentOS-$releasever - Extras
baseurl=http://ftp.riken.jp/Linux/centos/4.8/extras/$basearch/
gpgcheck=1
保存退出
重新导入新的GPG Key
#rpm --import http://ftp.riken.jp/Linux/centos/4.8/os/i386/RPM-GPG-KEY-centos4
5.测试是否配置成功
#yum update
看到如下内容证明yum配置成功