title: Split requirements files in pip
body: <p>To create Python virtual environments I use virtualenv and pip. The workflow is very simple:</p>
  
  <pre><code>$ virtualenv project
  $ cd project
  $ . bin/activate
  $ pip install -r /path/to/requirements/req1.txt
  $ pip install -r /path/to/requirements/req2.txt
  </code></pre>
  
  <p>The number of different requirement files can grow enough to make handy to have a way to include them at once, so I'd rather prefer to say:</p>
  
  <pre><code>$ pip install -r /path/to/requirements/req1_req2.txt
  </code></pre>
  
  <p>with <code>req1_req2.txt</code> containing something like:</p>
  
  <pre><code>include /path/to/requirements/req1.txt
  include /path/to/requirements/req2.txt
  </code></pre>
  
  <p>or otherwise:</p>
  
  <pre><code>$ pip install -r /path/to/requirements/*.txt
  </code></pre>
  
  <p>None of that works and however much simple it could be, I can't figure out how to do what I want.</p>
  
  <p>Any suggestion?</p>