思路：卸載Red Hat Enterprise Linux 6.4自帶yum，然後下載CentOS的yum，安裝後修改配置文件
1、首先到http://mirrors.163.com/centos下載軟件包
x86 地址：http://mirrors.163.com/centos/6/os/i386/Packages/
x86_64 地址：http://mirrors.163.com/centos/6/os/x86_64/Packages/
必要下載的軟件包有（以64位系統為例）：
a python-iniparse-0.3.1-2.1.el6.noarch.rpm
b yum-3.2.29-40.el6.centos.noarch.rpm
c yum-metadata-parser-1.1.2-16.el6.x86_64.rpm
d yum-plugin-fastestmirror-1.1.30-14.el6.noarch.rpm
下載命令：
wget http://mirrors.163.com/centos/6/os/x86_64/Packages/python-iniparse-0.3.1-2.1.el6.noarch.rpm
wget http://mirrors.163.com/centos/6/os/x86_64/Packages/yum-metadata-parser-1.1.2-16.el6.x86_64.rpm
wget http://mirrors.163.com/centos/6/os/x86_64/Packages/yum-3.2.29-40.el6.centos.noarch.rpm
wget http://mirrors.163.com/centos/6/os/x86_64/Packages/yum-plugin-fastestmirror-1.1.30-14.el6.noarch.rpm
[注] :版本不一定要最新的
2、卸載RedHat自帶的yum
rpm -qa | grep yum | xargs rpm -e --nodeps
注：a、xargs是一條Unix和類Unix操作系統的常用命令。它的作用是將參數列表轉換成小塊分段傳遞給其他命令，以避免參數列表過長的問題
b、--nodeps 強制卸載,不管依賴性
3、安裝下載的centos的yum包：
rpm -ivh python-iniparse-0.3.1-2.1.el6.noarch.rpm
rpm -ivh yum-metadata-parser-1.1.2-16.el6.x86_64.rpm
rpm -ivh yum-3.2.29-40.el6.centos.noarch.rpm yum-plugin-fastestmirror-1.1.30-14.el6.noarch.rpm
[注] :最後2個需要一起安裝，否則會出現依賴性錯誤
4、到http://mirrors.163.com的 centos幫助文檔 中下載CentOS6-Base-163.repo文件，存放到/etc/yum.repo.d中
wget http://mirrors.163.com/.help/CentOS6-Base-163.repo
5、編輯CentOS6-Base-163.repo文件，將其中的$releasever更改為centos的版本號
下面是修改好的：
# CentOS-Base.repo
#
# The mirror system uses the connecting IP address of the client and the
# update status of each mirror to pick mirrors that are updated to and
# geographically close to the client. You should use this for CentOS updates
# unless you are manually picking other mirrors.
#
# If the mirrorlist= does not work for you, as a fall back you can try the
# remarked out baseurl= line instead.
#
#
[base]
name=CentOS-6 - Base - 163.com
baseurl=http://mirrors.163.com/centos/6/os/$basearch/
#mirrorlist=http://mirrorlist.centos.org/?release=6&arch=$basearch&repo=os
gpgcheck=1
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-6
#released updates
[updates]
name=CentOS-6 - Updates - 163.com
baseurl=http://mirrors.163.com/centos/6/updates/$basearch/
#mirrorlist=http://mirrorlist.centos.org/?release=6&arch=$basearch&repo=updates
gpgcheck=1
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-6
#additional packages that may be useful
[extras]
name=CentOS-6 - Extras - 163.com
baseurl=http://mirrors.163.com/centos/6/extras/$basearch/
#mirrorlist=http://mirrorlist.centos.org/?release=6&arch=$basearch&repo=extras
gpgcheck=1
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-6
#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-6 - Plus - 163.com
baseurl=http://mirrors.163.com/centos/6/centosplus/$basearch/
#mirrorlist=http://mirrorlist.centos.org/?release=6&arch=$basearch&repo=centosplus
gpgcheck=1
enabled=0
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-6
#contrib - packages by Centos Users
[contrib]
name=CentOS-6 - Contrib - 163.com
baseurl=http://mirrors.163.com/centos/6/contrib/$basearch/
#mirrorlist=http://mirrorlist.centos.org/?release=6&arch=$basearch&repo=contrib
gpgcheck=1
enabled=0
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-6
6、yum clean all 清除原有緩存
7、yum makecache 獲取yum列表
出現下面提示，表示yum更改完成：
Metadata Cache Created
更多RedHat相關信息見RedHat 專題頁面 http://www.linuxidc.com/topicnews.aspx?tid=10
更多CentOS相關信息見CentOS 專題頁面 http://www.linuxidc.com/topicnews.aspx?tid=14
