title: Problem Xvfb using python 2.7 and selenium
body: <p>I have a problem using "Xvfb" with Selenium. In my requirement i have to open python with a bash script. if i execute it normally python like</p>
  
  <pre><code>python file.py
  </code></pre>
  
  <p>it doesn't have any problem, but if i execute it directly from bash the following error happens</p>
  
  <pre><code>start error &lt;EasyProcess cmd_param=['Xvfb', '-help'] cmd=['Xvfb', '-help'] oserror=[Errno 2] No such file or directory return_code=None stdout="None" stderr="None" timeout_happened=False&gt;
  
  </code></pre>
  
  <p>I don't know what happends, my code in python (where the error appears)</p>
  
  <pre><code>display = Display(visible=0, size=(800, 600))
  display.start()
  </code></pre>
  
  <p>and bash script</p>
  
  <pre><code>#!/bin/bash
  PYTHON="/usr/bin/python"
  MODULE="/home/user/file.py"
  $PYTHON $MODULE
  </code></pre>
  
  <p>I will be grateful for any response</p>
  
  <p>Edit:
  Full message in Except </p>
  
  <pre><code>Problem to open browser: start error &lt;EasyProcess cmd_param=['Xvfb', '-help'] cmd=['Xvfb', '-help'] oserror=[Errno 2] No such file or directory return_code=None stdout="None" stderr="None" timeout_happened=False&gt;
  EXCEPTION IN (main.py, LINE 2148 "display = Display(visible=0, size=(800, 600))"): start error &lt;EasyProcess cmd_param=['Xvfb', '-help'] cmd=['Xvfb', '-help'] oserror=[Errno 2] No such file or directory return_code=None stdout="None" stderr="None" timeout_happened=False&gt;
  </code></pre>