在 64位版本的 Linux 上使用 yum 安装软件包的时候如果不小心的话会同时安装 i386 和 x86_64 版本的软件，如下面安装的 httpd-devel 就有 i386 和 x86_64 两个版本：

[code]# yum install httpd-devel
...
Dependencies Resolved

================================================================================
Package              Arch       Version        &

想用yum 安装一个包，发现yum不能使用如下。

[code][root@done1 yum]# yum
There was a problem import

用yum更新系统是一件很痛苦的事情，缓慢的进度都让你想把鼠标扔出去。不过我们通过两个办法就能极大地提高yum安装软件的速度。

首先，安装yum-fastestmirror插件
yum -y install yum-fastestmirror

然后，安装多线程下载工具axel
wget http://alioth.debian.org/frs/download.php/2621/axel-2.2.tar.bz2
bzip2 -d axel-2.2.tar.bz2
tar xvf axel-2.2.tar
cd axel
./configure
make && make install

最后，安装yum的axelget插件
svn co http://cnfreesoft.googlecode.com/svn/trunk/axelget/ /etc/yum/axelget
cd /etc/yum/pluginconf.d/
ln -s /etc/yum/axelget/axelget.conf .
cd /usr/lib/yum-plugins/
ln -s /etc/yum/axelget/axelget.py .
修改/etc/yum.conf，设置plugins=1，一切搞定，运行yum -y update，享受一下高速的感觉吧。

/etc/yum.repos.d/CentOS-Base.repo

[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://mirror.be10.com/centos/$releasever/os/$basearch/
        http://ftp.hostrino.com/pub/centos/$releasever/os/$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=$basearch&repo=updates
baseurl=http://mirror.be10.com/centos/$releasever/updates/$basearch/
        http://ftp.hostrino.com/pub/centos/$releasever/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=$basearch&repo=addons
baseurl=http://mirror.be10.com/centos/$releasever/addons/$basearch/
        http://ftp.hostrino.com/pub/centos/$releasever/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://mirror.be10.com/centos/$releasever/extras/$basearch/
        http://ftp.hostrino.com/pub/centos/$releasever/extras/$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=$basearch&repo=centosplus
baseurl=http://mirror.be10.com/centos/$releasever/centosplus/$basearch/
        http://ftp.hostrino.com/pub/centos/$releasever/centosplus/$basearch/
gpgcheck=1
enabled=0
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-centos5

#contrib - packages by Centos Users
[contrib]
name=CentOS-5 - Contrib
#mirrorlist=http://mirrorlist.centos.org/?release=4&arch=$basearch&repo=contrib
baseurl=http://mirror.be10.com/centos/$releasever/contrib/$basearch/
        http://ftp.hostrino.com/pub/centos/$releasever/contrib/$basearch/
gpgcheck=1
enabled=0
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-centos5