要能够使用import tab，最主要的是要有readline模块。默认python2.6虽然没有装tab模块，但是装了readline模块的。如下：
[root@90-163 robin]# python2.6
Python 2.6.6 (r266:84292, Nov 22 2013, 12:16:22)
[GCC 4.4.7 20120313 (Red Hat 4.4.7-4)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import tab
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ImportError: No module named tab
>>> import readline
>>>
而python2.7默认tab模块和readline模块都没有安装
[root@90-163 robin]# python
Python 2.7.5 (default, Apr 16 2015, 15:21:18)
[GCC 4.4.7 20120313 (Red Hat 4.4.7-4)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import tab
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ImportError: No module named tab
>>> import readline
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ImportError: No module named readline
python2.6能够import readline成功的原因是因为有这个模块：/usr/lib64/python2.6/lib-dynload/readline.so （默认安装就有的），python2.7.5不能import readline成功的原因就是没有这个模块。所以将这个模块cp到python2.7的相关目录下既可以了。操作如下：
[root@90-163 lib-dynload]# cp /usr/lib64/python2.6/lib-dynload/readline.so /usr/local/lib/python2.7/lib-dynload/
[root@90-163 lib-dynload]# python
Python 2.7.5 (default, Apr 16 2015, 15:21:18)
[GCC 4.4.7 20120313 (Red Hat 4.4.7-4)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import readline
>>>
然后在/usr/local/lib/python2.7/site-packages 添加一个tab.py文件即可使用import tab，内容如下；
[root@90-163 site-packages]# pwd
/usr/local/lib/python2.7/site-packages
[root@90-163 site-packages]# cat tab.py
try:
import readline
except ImportError:
print("Module readline not available.")
else:
import rlcompleter
readline.parse_and_bind("tab: complete")
进行测试：
>>> import readline
>>> import tab
>>> import os
>>> os.w
os.wait( os.wait3( os.wait4( os.waitpid( os.walk( os.write(
