第一步：卸载rhel的默认安装的yum包
查看yum包
rpm -qa|grep yum
卸载之
rpm -qa|grep yum|xargs rpm -e --nodeps
第二步：下载新的yum包
打开网页
找到下列rpm包，下载并安装
yum-3.2.22-26.el5.CentOS.noarch.rpm
yum-fastestmirror-1.1.16-14.el5.centos.1.noarch.rpm
yum-metadata-parser-1.1.2-3.el5.centos.i386.rpm
并且安装之
rpm -ivh yum-*
注意：yum和yum-fastestmirror相互依赖，所以同时安装即可。
第三步：下载yum的配置源
下载到 /etc/yum.repos.d/ 目录下面
第四步：运行yum makecache生成缓存
[root@localhost yum.repos.d]# yum makecache
There was a problem importing one of the Python modules
required to run yum. The error leading to this problem was:
No module named yum
Please install a package which provides this module, or
verify that the module is installed correctly.
It's possible that the above module doesn't match the
current version of Python, which is:
2.7.2 (default, Mar 11 2012, 03:08:10)
[GCC 4.1.2 20080704 (Red Hat 4.1.2-46)]
If you cannot solve this problem yourself, please go to
the yum faq at:
我在做第四步的时候出现上面的错误，原因是我升级了python， 解决方法如下
[root@localhost yum.repos.d]# whereis python
python: /usr/bin/python /usr/bin/python2.4 /usr/lib/python1.5 /usr/lib/python2.4 /usr/local/bin/python2.7 /usr/local/bin/python2.7-config /usr/local/bin/python /usr/local/lib/python2.7 /usr/include/python2.4 /usr/share/man/man1/python.1.gz
[root@localhost yum.repos.d]# vi /usr/bin/yum
#!/usr/bin/python
import sys
把第一行修改为 #!/usr/bin/python2.4， 然后保存退出。
[root@localhost yum.repos.d]# yum makecache
Loaded plugins: fastestmirror
Determining fastest mirrors
addons | 1.9 kB 00:00
addons/filelists_db | 564 B 00:00
addons/other_db | 552 B 00:00
addons/primary_db | 1.1 kB 00:00
base | 1.1 kB 00:00
base/filelists | 3.0 MB 00:01
这样就成功了。