title: python subprocess insert commands inside of a running subprocess
body: <p>I have a subprocess running:</p>
  
  <pre><code>cmd="bin/candc --models models"
  subprocess.check_output('{} | tee /dev/stderr'.format( cmd ), shell=True,cwd=os.path.abspath('candc'))
  </code></pre>
  
  <p>and i want to be able to insert more commands that is recognized only by the currently running subprocess.<br>
  note that there must be a <code>cwd=os.path.abspath('candc')</code> parameter so that the subprocess would be called from outside of the binary folder, otherwise it won't run.<br>
  <strong><a href="http://svn.ask.it.usyd.edu.au/trac/candc/wiki/Documentation" rel="nofollow">C&amp;C</a></strong> is a NLP library and what it is actually going to do is to parse a given sentence. I want to be able to pass a sentence to the subprocess. how can I do this ?</p>