title: shell_exec not running in websever
body: <p>I have an apache web sever with php file <code>/var/www/html/test.php</code>, and <code>servo.py</code> in the same directory.
  When I go to <code>localhost/test.php</code> it doesn't work. Yet when I run <code>test.php</code> in an IDE it works fine. Any help?</p>
  
  <p>test.php:</p>
  
  <pre><code>&lt;?php
      shell_exec("python servo.py");
  ?&gt;
  </code></pre>