1、查询redhat原有的yum
[root@localhost ~]# rpm -qa |grep yum
yum-metadata-parser-1.1.2-16.el6.x86_64
yum-rhn-plugin-0.9.1-40.el6.noarch
yum-plugin-security-1.1.30-14.el6.noarch
PackageKit-yum-0.5.8-20.el6.x86_64
yum-utils-1.1.30-14.el6.noarch
PackageKit-yum-plugin-0.5.8-20.el6.x86_64
2、删除redhat原有的yum
[root@localhost ~]# rpm -aq|grep yum|xargs rpm -e --nodeps
[root@localhost yum.repos.d]# whereis yum
yum: /etc/yum
[root@localhost yum.repos.d]# rm -rf /etc/yum
3、下载yum安装文件
在下载地址（http://mirrors.163.com/centos/6.6/os/x86_64/Packages/） 中
（以后centos升级，软件包会挪位置，一般从http://mirrors.163.com/centos 进去，找最新的系统版本即可）
rpm文件：
python-iniparse-0.3.1-2.1.el6.noarch.rpm
yum-3.2.29-60.el6.centos.noarch.rpm
yum-metadata-parser-1.1.2-16.el6.x86_64.rpm
yum-plugin-fastestmirror-1.1.30-30.el6.noarch.rpm
4、安装yum的rpm包
rpm -ivh python*
rpm -ivh yum*
[root@localhost yum]# rpm -ivh python-iniparse-0.3.1-2.1.el6.noarch.rpm
warning: python-iniparse-0.3.1-2.1.el6.noarch.rpm: Header V3 RSA/SHA256 Signature, key ID c105b9de: NOKEY
Preparing... ########################################### [100%]
package python-iniparse-0.3.1-2.1.el6.noarch is already installed
[root@localhost yum]# rpm -ivh yum-*
warning: yum-3.2.29-60.el6.centos.noarch.rpm: Header V3 RSA/SHA1 Signature, key ID c105b9de: NOKEY
Preparing... ########################################### [100%]
1:yum-metadata-parser ########################################### [ 33%]
2:yum-plugin-fastestmirro########################################### [ 67%]
3:yum ########################################### [100%]
[root@localhost yum]# 5、更改yum源（我们使用网易的CentOS镜像源）
[root@localhost yum]# cd /etc/yum.repos.d/
[root@localhost yum.repos.d]# rm -rf *
[root@localhost yum.repos.d]# wget http://mirrors.163.com/.help/CentOS6-Base-163.repo
[root@localhost yum.repos.d]# vi CentOS6-Base-163.repo
将所有 $releasever 修改为具体的版本号，我这里写的是6.6，以后centos再更新，有可能是6.7、6.8等，这个自己打开（http://mirrors.163.com/centos）找一下就可以。
如下为服务器操作记录：
[root@localhost yum]# cd /etc/yum.repos.d/
[root@localhost yum.repos.d]# ll
total 12
-rw-r--r--. 1 root root 4440 Nov 20 02:30 CentOS-Base.repo
-rw-r--r--. 1 root root 529 May 30 2012 rhel-source.repo.bak
[root@localhost yum.repos.d]# rm -rf *
[root@localhost yum.repos.d]# wget http://mirrors.163.com/.help/CentOS6-Base-163.repo
--2014-11-20 18:55:19-- http://mirrors.163.com/.help/CentOS6-Base-163.repo
Resolving mirrors.163.com... 123.58.173.106
Connecting to mirrors.163.com|123.58.173.106|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 2006 (2.0K) [application/octet-stream]
Saving to: ?.entOS6-Base-163.repo?
100%[=======================================================>] 2,006 --.-K/s in 0.03s
2014-11-20 18:55:19 (63.8 KB/s) - ?.entOS6-Base-163.repo?.saved [2006/2006]
[root@localhost yum.repos.d]# vi CentOS6-Base-163.repo我的 CentOS6-Base-163.repo 内容如下：
# CentOS-Base.repo
#
# The mirror system uses the connecting IP address of the client and the
# update status of each mirror to pick mirrors that are updated to and
# geographically close to the client. You should use this for CentOS updates
# unless you are manually picking other mirrors.
#
# If the mirrorlist= does not work for you, as a fall back you can try the
# remarked out baseurl= line instead.
#
#
[base]
name=CentOS-$releasever - Base - 163.com
baseurl=http://mirrors.163.com/centos/6.6/os/$basearch/
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os
gpgcheck=1
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-6
#released updates
[updates]
name=CentOS-$releasever - Updates - 163.com
baseurl=http://mirrors.163.com/centos/6.6/updates/$basearch/
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=updates
gpgcheck=1
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-6
#additional packages that may be useful
[extras]
name=CentOS-$releasever - Extras - 163.com
baseurl=http://mirrors.163.com/centos/6.6/extras/$basearch/
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extras
gpgcheck=1
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-6
#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-$releasever - Plus - 163.com
baseurl=http://mirrors.163.com/centos/6.6/centosplus/$basearch/
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=centosplus
gpgcheck=1
enabled=0
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-6
#contrib - packages by Centos Users
[contrib]
name=CentOS-$releasever - Contrib - 163.com
baseurl=http://mirrors.163.com/centos/6.6/contrib/$basearch/
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=contrib
gpgcheck=1
enabled=0
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-66、缓存处理
清理yum缓存
yum clean all
将服务器上的软件包信息缓存到本地,以提高搜索安装软件的速度
yum makecache
安装gcc
yum install gcc
至此，我们就可以使用yum安装和更新软件了。
结束
