title: Python subprocess returned non-zero exit status -6
body: <p>this is my first post on stackoverflow. I hope my question is not to stupid:)</p>
  
  <p>I'm using django to develop a website, inside the django I need to grab thumbnail of website, so I use <a href="https://github.com/coderholic/PyWebShot" rel="nofollow">https://github.com/coderholic/PyWebShot</a> to achieve it.</p>
  
  <p>I run PyWebShot in django shell with subprocess it work well, but when I put django into apache2 and access it with a url then it fail.</p>
  
  <p>Here is the error message:</p>
  
  <blockquote>
    <p>CalledProcessError at GIVEN_URL</p>
    
    <p>Command '['echo', '$HOME']' returned non-zero exit status -6</p>
  </blockquote>
  
  <p>It fail on this command actually:</p>
  
  <pre><code>subprocess.check_output(['echo', '$HOME'])
  </code></pre>
  
  <p>I've tried write output and error of the process into a file, but the file always empty.</p>
  
  <p>I'm hoping someone can give me a note or direction, Thanks!</p>
  
  <p>ps: If need more information please just let me know.</p>