1.下载并安装yum-2.4.0-1.centos4.noarch.rpm文件，下载地址为：
ftp://ftp.pbone.net/mirror/ftp.centos.org/5.0/os/i386/CentOS/yum-cron-0.1-1.el5.centos.noarch.rpm
2.修改或建立/etc/yum.repos.d/rhel-debuginfo.repo为如下内容：
[base]
name=Red Hat Enterprise Linux $releasever -Base
baseurl=http://ftp.riken.jp/Linux/caos/centos/5.0/os/$basearch/
gpgcheck=1
[update]
name=Red Hat Enterprise Linux $releasever -Updates
baseurl=http://ftp.riken.jp/Linux/caos/centos/5.0/updates/$basearch/
gpgcheck=1
[extras]
name=Red Hat Enterprise Linux $releasever -Extras
baseurl=http://ftp.riken.jp/Linux/caos/centos/5.0/extras/$basearch/
gpgcheck=1
[addons]
name=Red Hat Enterprise Linux $releasever -Addons
baseurl=http://ftp.riken.jp/Linux/caos/centos/5.0/addons/$basearch/
gpgcheck=1
3.修改或建立/etc/yum.repos.d/dag.repo为如下内容：
[dag]
name=Dag RPM Repository for RHEL5
baseurl=http://ftp.riken.jp/Linux/dag/redhat/el5/en/$basearch/dag/
enabled=1
gpgcheck=1
gpgkey=http://ftp.riken.jp/Linux/dag/packages/RPM-GPG-KEY.dag.txt
4.运行update:
yum update
5.升级：
yum upgrade
