title: Python can't see modules installed with pip
body: <p>I'm working in a brand new Python virtualenv. I've just installed <code>httplib2</code> using pip, but Python cannot see it. </p>
  
  <pre><code>(venv)$ sudo pip install httplib2
  Requirement already satisfied (use --upgrade to upgrade): httplib2 in     
  /usr/local/lib/python2.7/dist-packages
  Cleaning up...
  (venv)$ python
  Python 2.7.3 (default, Sep 26 2013, 20:03:06) 
  [GCC 4.6.3] on linux2
  Type "help", "copyright", "credits" or "license" for more information.
  &gt;&gt;&gt; import httplib2
  Traceback (most recent call last):
   File "&lt;stdin&gt;", line 1, in &lt;module&gt;
   ImportError: No module named httplib2
  </code></pre>
  
  <p>From my reading, it sounds like this is probably a path problem, but I don't know why it is happening, or how to fix it :(</p>
  
  <p>This is the content of <code>sys.path</code>:</p>
  
  <pre><code>&gt;&gt;&gt; pprint(sys.path)
  ['',
   '/var/apps/ttex/venv/local/lib/python2.7/site-packages/distribute-0.6.24-py2.7.egg',
   '/var/apps/ttex/venv/local/lib/python2.7/site-packages/pip-1.1-py2.7.egg',
   '/var/apps/ttex/venv/lib/python2.7/site-packages/distribute-0.6.24-py2.7.egg',
   '/var/apps/ttex/venv/lib/python2.7/site-packages/pip-1.1-py2.7.egg',
   '/var/apps/ttex/venv/lib/python2.7',
   '/var/apps/ttex/venv/lib/python2.7/plat-linux2',
   '/var/apps/ttex/venv/lib/python2.7/lib-tk',
   '/var/apps/ttex/venv/lib/python2.7/lib-old',
   '/var/apps/ttex/venv/lib/python2.7/lib-dynload',
   '/usr/lib/python2.7',
   '/usr/lib/python2.7/plat-linux2',
   '/usr/lib/python2.7/lib-tk',
   '/var/apps/ttex/venv/local/lib/python2.7/site-packages',
   '/var/apps/ttex/venv/lib/python2.7/site-packages']
  </code></pre>
  
  <p>Oddly though, if I run Python 2.7, I can see the package: </p>
  
  <pre><code>(venv)$ python2.7
  &gt;&gt;&gt; import httplib2
  &gt;&gt;&gt; 
  </code></pre>
  
  <p>Why is this happening and what can I do about it?</p>
  
  <p>Sorry if this is a duplicate, there are lots of questions around this topic, but none seem to give a simple definitive answer. </p>