Python: cannot import urandom module (OS X)

问题

I'm quite ashamed to ask a question like this one, but I've been trying for a couple of hours already...it seems I can't get my python version to do random things anymore. More precisely, it's missing the module urandom.

First, here are some info about my system:

OSX version: 10.7.4
python version: Python 2.7.1
which python: /opt/local/bin/python
import os; os: <module 'os' from '/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.pyc'>
echo $PATH: /opt/local/bin:/opt/local/sbin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/usr/X11/bin:/usr/local/git/bin
$ENV and $PYTHONPATH are empty

Now, when I have a deeper look and do vim /opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/random.py, I can see this file requires urandom:

line 47: from os import urandom as _urandom

So, quite logically, I have failures when I try running:

>>> import random
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/random.py", line 47, in <module>
    from os import urandom as _urandom
ImportError: cannot import name urandom

Any ideas? Where is urandom supposed to live? I've been googling around without success so far.
It seems a lot of Ubuntu users had this problem with virtualenv, but I'm not using virtualenv, and I'm not on Ubuntu. My bet is that somehow my PATH or PYTHONPATH or ENV variables are not set properly, but I have no idea how to solve this.

回答1:

Ok, I figured it out. I had a dirty hash table in my terminal.

Solution:

hash -r  # will erase the currently used hash table

Once this was done, I ran python again and I got:

Python 2.7.3 (default, Apr 19 2012, 00:55:09) 
[GCC 4.2.1 (Based on Apple Inc. build 5658) (LLVM build 2335.15.00)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import random
>>> import os; os
<module 'os' from '/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.pyc'>

Note the different python version (2.7.3 vs 2.7.1 before). I think this is due to an earlier install of python 2.3 via mac port.

Sorry for the question/quick answer :/

Have a good night!
Arnaud

来源：https://stackoverflow.com/questions/12658141/python-cannot-import-urandom-module-os-x

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