查看当前系统版本

[root@dcmail2 ~]# lsb_release -a

LSB Version::core-3.0-ia32:core-3.0-noarch:graphics-3.0-ia32:graphics-3.0-noarch

Distributor ID:RedHatEnterpriseAS

Description:Red Hat Enterprise Linux AS release 4 (Nahant Update 4)

Release:4

Codename:NahantUpdate4

下载并安装YUM包

1.下载

wget http://yum.baseurl.org/download/2.0/yum-2.0.8-1.src.rpm 

2.安装(由于是RPM源码包所以安装比较特殊) 

rpmbuild --rebuild yum-2.0.8-1.src.rpm

3.进入到:/usr/src/redhat/RPMS/noarch/

rpm -ivh yum-2.0.8-1.noarch.rpm

4.配置文件/etc/yum.conf （注释部分为默认值，测试不可用，需要手动添加可用的源）

[root@dcmail2 ~]# cat /etc/yum.conf 

[main]

cachedir=/var/cache/yum

debuglevel=2

logfile=/var/log/yum.log

pkgpolicy=newest

distroverpkg=redhat-release

tolerant=1

exactarch=1

[base]

name=Red Hat Linux $releasever - $basearch - Base

#baseurl=http://mirror.dulug.duke.edu/pub/yum-repository/redhat/$releasever/$basearch/

baseurl=http://vault.centos.org/4.4/os/x86_64/

gpgcheck=1

[updates]

name=Red Hat Linux $releasever - Updates

#baseurl=http://mirror.dulug.duke.edu/pub/yum-repository/redhat/updates/$releasever/

baseurl=http://vault.centos.org/4.4/updates/x86_64/

gpgcheck=1

过程中遇到的问题

Gathering header information file(s) from server(s)

Server: Red Hat Linux 4AS - i386 - Base

Server: Red Hat Linux 4AS - Updates

retrygrab() failed for:

  http://vault.centos.org/4.4/updates/headers/header.info

  Executing failover method

failover: out of servers to try

Error getting file http://vault.centos.org/4.4/updates/headers/header.info

[Errno 4] IOError: HTTP Error 404: Not Found

安装配置完毕后 yum list 报错，提示找不到header.info （之前百度上的大多数文档路径已过时，按照那个路径确实找不到，自己登录网站确定下header文件的位置更新下就行了）

只要是有4系的源，找到header路径 就可以添加上使用