yum源设置路径
/etc/yum.repos.d/
新建或复制一个文件 后缀名为repo再倒入key即可
以中国科技大学源为例
新建ustc.repo
内容为
#centos-ustc-edu-cn.repo
#
# 中国科技大学，速度不错
# rpm --import http://centos.ustc.edu.cn/centos/RPM-GPG-KEY-CentOS-5
#
# This file uses a new mirrorlist system developed by Lance Davis for CentOS.
# 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 CentOS updates
# 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-5 - Base
repo=os
baseurl=http://centos.ustc.edu.cn/centos/5.6/os/$basearch/
gpgcheck=1
gpgkey=http://centos.ustc.edu.cn/centos/RPM-GPG-KEY-CentOS-5
[update]
name=CentOS-5 - Updates
baseurl=http://centos.ustc.edu.cn/centos/5.6/updates/$basearch/
gpgcheck=1
gpgkey=http://centos.ustc.edu.cn/centos/RPM-GPG-KEY-CentOS-5
[addons]
name=CentOS-5 - Addons
baseurl=http://centos.ustc.edu.cn/centos/5.6/addons/$basearch/
gpgcheck=1
gpgkey=http://centos.ustc.edu.cn/centos/RPM-GPG-KEY-CentOS-5
[extras]
name=CentOS-5 - Extras
baseurl=http://centos.ustc.edu.cn/centos/5.6/extras/$basearch/
gpgcheck=1
gpgkey=http://centos.ustc.edu.cn/centos/RPM-GPG-KEY-CentOS-5
[centosplus]
name=CentOS-5 - Plus
baseurl=http://centos.ustc.edu.cn/centos/5.6/centosplus/$basearch/
gpgcheck=1
enabled=0
gpgkey=http://centos.ustc.edu.cn/centos/RPM-GPG-KEY-CentOS-5
[contrib]
name=CentOS-5 - Contrib
baseurl=http://centos.ustc.edu.cn/centos/5.6/contrib/$basearch/
gpgcheck=1
enabled=0
gpgkey=http://centos.ustc.edu.cn/centos/RPM-GPG-KEY-CentOS-5
源都添加完了之后，再装个插件，yum install yum-fastestmirror -y，这个会自动选择快的那个源。 如果我在那个目录里放了很多源，怎么知道当前用的是那个呢？如果你没有改yum.conf，那么看/var/cache/yum/文件夹里的一个time开头的文件，就知道了 如果在使用yum install安装找不到某些包的时候，可以使用下面办法试试
导入key rpm --import http://centos.ustc.edu.cn/centos/RPM-GPG-KEY-CentOS-5
rpm -Uvh rpmforge-release-0.3.6-1.el5.rf.i386.rpm
