No module named yum 错误

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, Nov  8 2012, 23:03:00)
[GCC 4.1.2 20080704 (Red Hat 4.1.2-48)]

If you cannot solve this problem yourself, please go to
the yum faq at: http://wiki.linux.duke.edu/YumFaq[/code] 
错误提示python版本不匹配，修改yum工具默认的python版本。

vi /usr/bin/yum
打开脚本文件

#!/usr/bin/python
import sys
try:
import yum
。。。。。。。
修改为

#!/usr/bin/python2.4
import sys
try:
import yum
except ImportError:
因为重新升级或者安装了python，所以重新指定版本。

测试OK。