title: How to run pip from different versions of python using the python command?
body: <p>I'm now currently using Python on Ubuntu 15.10.</p>
  <p>But in my OS, I have many different python versions installed:</p>
  <ul>
  <li>Python (2.7.9)</li>
  <li>Python3 (3.4.3)</li>
  <li>Python3.5</li>
  <li>PyPy</li>
  </ul>
  <p>So, it got messy with the versions of the packages in different environments. For example, if I run:</p>
  <pre><code>pip3 install django
  </code></pre>
  <p>But in fact, I cannot import django inside <code>python3.5</code>.</p>
  <p>Is there any efficient way to call the correct version of <code>pip</code>?</p>
  <p>Note:<br />
  <em>Don't suggest that I use virtualenv, I know about it and am seeking another solution.</em></p>