1.备份原有yum源 #mv /etc/yum.repos.d/CentOS6-Base.repo /etc/yum.repos.d/CentOS6-Base-163.repo_bak 2.卸载当前
1.备份原有yum源
#mv /etc/yum.repos.d/CentOS6-Base.repo /etc/yum.repos.d/CentOS6-Base-163.repo_bak2.卸载当前yum
rpm -qa | grep yum | xargs rpm -e --nodeps
3.下载安装rpm文件
64位系统下载地址：
http://mirrors.163.com/centos/6/os/x86_64/Packages/
32位系统下载地址：
http://mirrors.163.com/centos/6/os/i386/Packages/
4.下载文件有5个
wget http://mirrors.163.com/centos/6/os/x86_64/Packages/yum-3.2.29-81.el6.centos.noarch.rpmwget http://mirrors.163.com/centos/6/os/x86_64/Packages/yum-metadata-parser-1.1.2-16.el6.x86_64.rpm wget http://tel.mirrors.163.com/centos/6/os/x86_64/Packages/yum-plugin-fastestmirror-1.1.30-37.el6.noarch.rpm wget http://tel.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/python-urlgrabber-3.9.1-11.el6.noarch.rpm5.安装软件包
rpm -ivh python-iniparse-0.3.1-2.1.el6.noarch.rpm rpm -ivh python-urlgrabber-3.9.1-11.el6.noarch.rpm rpm -ivh yum-metadata-parser-1.1.2-16.el6.x86_64.rpm rpm -ivh yum-plugin-fastestmirror-1.1.30-40.el6.noarch.rpm yum-3.2.29-81.el6.centos.noarch.rpm 后面两个同时安装（yum-plugin-fastestmirror和yum-3.2.29要一起安装。），防止相互依赖。
安装问题：
如果按照遇到问题：发现错误，python-urlgrabber版本必须大于等于3.9.1-10
# rpm -ivh yum-3.2.29-73.el6.centos.noarch.rpm yum-plugin-fastestmirror-1.1.30-37.el6.noarch.rpmwarning: yum-3.2.29-73.el6.centos.noarch.rpm: Header V3 RSA/SHA1 Signature, key ID c105b9de: NOKEYerror: Failed dependencies: python-urlgrabber >= 3.9.1-10 is needed by yum-3.2.29-73.el6.centos.noarch查看系统的python信息
#rpm -qa|grep python查看 python-urlgrabber 的版本，从查看结果中卸载python-urlgrabber。
#rpm -e python-urlgrabber-3.9.1-9.el6.noarch重新安装：
#rpm -ivh python-urlgrabber-3.9.1-11.el6.noarch.rpm6.清楚yum缓存：
yum clean all7.更改yum源
# cd /etc/yum.repos.d/下载：
# wget http://mirrors.163.com/.help/CentOS6-Base-163.repo把$releasever替换成现有系统的版本号(数字6)，使用vim替换命令
# vim CentOS6-Base-163.repo ：%s/$releasever/6/g:wq 退出保存，再次清理yum缓存
# yum clean all将服务器软件包信息缓存至本地，提高搜索安装效率
# yum makecache8.测试
# yum seach vim应该可以成功安装了。
9.epel-release无法完成安装
在安装webmin面板的时候到最后出现了安装错误的提示.然后更新源时发现
或者在#yum install epel-release的时候，报错，错误信息如下。
Error: Cannot retrieve metalink for repository: epel. Please verify its path and try again主要是源文件有点问题,解决方案如下
vim /etc/yum.repos.d/epel.repo将
[epel]
name=Extra Packages for Enterprise Linux 6 - $basearch
#baseurl=http://download.fedoraproject.org/pub/epel/6/$basearch
mirrorlist=https://mirrors.fedoraproject.org/metalink?repo=epel-6&arch=$basearch
修改为
[epel]
name=Extra Packages for Enterprise Linux 6 - $basearch
baseurl=http://download.fedoraproject.org/pub/epel/6/$basearch
#mirrorlist=https://mirrors.fedoraproject.org/metalink?repo=epel-6&arch=$basearch
最后在清理一下源
# yum clean all另类解决方案（引自http://www.111cn.net/sys/CentOS/99413.htm）
有些时候服务器默认的DNS服务器为:127.0.0.1,我们更新一下DNS服务即可解决相关的问题.
直接修改
vi /etc/resolv.conf
列如我修改为GOOGLE DNS
nameserver 8.8.4.4
nameserver 8.8.8.8
如果还是出现问题，最高重启一下网络
/etc/init.d/networking restart
