linux CentOS 5.3 yum源配置过程详解

原文见
http://hi.baidu.com/dilijia1002/blog/item/405d8e19407cdc73dab4bd18.html 
1.以root用户进入CentOS系统。
[root@xuxy ~]# cd /etc/yum.repos.d
2.备份repo
[root@xuxy yum.repos.d]# mv CentOS-Base.repo CentOS-Base.repo.bak
3.建立新的CentOS-Base.repo文件：（以CentOS 5.3为例）
[root@xuxy yum.repos.d]#vi CentOS-Base.repo
内容如下:
[base]
name=CentOS-5 - Base
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever5&arch=$basearch&
repo=os
#baseurl=http://mirror.centos.org/centos/$releasever/os/$basearch/
baseurl=http://ftp.sjtu.edu.cn/centos/5.3/os/$basearch/
gpgcheck=1
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-centos5
 
#released updates
[update]
name=CentOS-5 - Updates
#mirrorlist=http://mirrorlist.centos.org/?release=4&arch=$basearch&repo=updates
baseurl=http://ftp.sjtu.edu.cn/centos/5.3/updates/$basearch/
gpgcheck=1
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-centos5
 
#packages used/produced in the build but not released
[addons]
name=CentOS-5 - Addons
#mirrorlist=http://mirrorlist.centos.org/?release=4&arch=$basearch&repo=addons
 
baseurl=http://ftp.sjtu.edu.cn/centos/5.3/addons/$basearch/
gpgcheck=1
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-centos5
 
#additional packages that may be useful
[extras]
name=CentOS-5 - Extras
#mirrorlist=http://mirrorlist.centos.org/?release=4&arch=$basearch&repo=extras
 
baseurl=http://ftp.sjtu.edu.cn/centos/5.3/extras/$basearch/
gpgcheck=1
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-centos5
 
#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-5 - Plus
#mirrorlist=http://mirrorlist.centos.org/?release=4&arch=$basearch&repo=centosplus
baseurl=http://ftp.sjtu.edu.cn/centos/5.3/centosplus/$basearch/
gpgcheck=1
enabled=0
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-centos5
 
#contrib - packages by Centos Users
[contrib]
na