title: Activate virtualenv via os.system()
body: <p>I'm writing a Python-based shell script to boilerplate a Django app with virtualenv, pip, and fabric. Should be straightforward enough, but it appears that I'm not able to activate and run commands in the virtualenv through the shell script.</p>
  
  <pre><code>os.system('virtualenv %s --no-site-packages' % project_name)
  os.system('source %s/bin/activate' % project_name)
  os.system('easy_install pip')
  </code></pre>
  
  <p>When running, this errors out:</p>
  
  <pre><code>$ startproject+ -s false sample
  New python executable in sample/bin/python
  Installing setuptools............done.
  /testing
  Searching for pip
  Best match: pip 0.4
  Processing pip-0.4-py2.6.egg
  pip 0.4 is already the active version in easy-install.pth
  Installing pip script to /usr/local/bin
  error: /usr/local/bin/pip: Permission denied
  </code></pre>
  
  <p>Obviously the <code>source</code> line isn't being run, but why? Is it a concurrency/threading issue, or something deeper with virtualenv?</p>
  
  <p>Thanks!</p>