在CentOS系统中，yum是个好东西，一组件可以直接通过yum来安装，但系统默认的yum源速度往往不尽人意，为了达到快递安装的目的，在这里就需要修改yum源
中科大的Centos 开源镜像站点. http://centos.ustc.edu.cn/
执行以下命令就可以了
cd /etc/yum.repos.d
mv CentOS-Base.repo CentOS-Base.repo.bak
wget http://centos.ustc.edu.cn/CentOS-Base.repo.5
mv CentOS-Base.repo.5 CentOS-Base.repo
cat CentOS-Base.repo
[base] name=CentOS-$releasever - Base baseurl=http://centos.ustc.edu.cn/centos/$releasever/os/$basearch/ gpgcheck=1 gpgkey=http://centos.ustc.edu.cn/centos/RPM-GPG-KEY-CentOS-5 #released updates [updates] name=CentOS-$releasever - Updates baseurl=http://centos.ustc.edu.cn/centos/$releasever/updates/$basearch/ gpgcheck=1 gpgkey=http://centos.ustc.edu.cn/centos/RPM-GPG-KEY-CentOS-5 #packages used/produced in the build but not released [addons] name=CentOS-$releasever - Addons baseurl=http://centos.ustc.edu.cn/centos/$releasever/addons/$basearch/ gpgcheck=1 gpgkey=http://centos.ustc.edu.cn/centos/RPM-GPG-KEY-CentOS-5 #additional packages that may be useful [extras] name=CentOS-$releasever - Extras baseurl=http://centos.ustc.edu.cn/centos/$releasever/extras/$basearch/ gpgcheck=1 gpgkey=http://centos.ustc.edu.cn/centos/RPM-GPG-KEY-CentOS-5 #additional packages that extend functionality of existing packages [centosplus] name=CentOS-$releasever - Plus baseurl=http://centos.ustc.edu.cn/centos/$releasever/centosplus/$basearch/ gpgcheck=1 enabled=0 gpgkey=http://centos.ustc.edu.cn/centos/RPM-GPG-KEY-CentOS-5
也可以使用， http://mirrors.163.com/ http://mirrors.sohu.com
