title: Running Selenium Webdriver on Xvfb - firefox error
body: <p>I'm trying to run some automated Selenium tests on a server at work running on centros with firefox 10.0.12 installed as follows:</p>
  
  <pre><code>Xvfb :99 -screen 0 800x600x16&amp;
  export DISPLAY=:99;
  java -jar ./autotesting/selenium-server-standalone-2.28.0.jar&amp;
  php ./autotesting/index.php;
  </code></pre>
  
  <p>index.php points to a SimpleTest test class that starts up a WebDriver session like this (using the facebook php bindings):</p>
  
  <pre><code>$webdriver = new WebDriver();
  $this-&gt;session = $webdriver-&gt;session('firefox');
  $this-&gt;session-&gt;open($this-&gt;url);
  </code></pre>
  
  <p>It runs on my local machine but on the server I get the following output:</p>
  
  <pre><code>13:17:11.344 INFO - Executing: [new session: {browserName=firefox}] at URL: /session)
  org.openqa.selenium.firefox.NotConnectedException: Unable to connect to host 127.0.0.1 on       port 7055 after 45000 ms. Firefox console output:
  mkdir: `99/.mozilla/extensions/{ec8030f7-c20a-464f-9b0e-13a3a9e97384}': Not a directory
  
  (Gecko:8766): libgnomevfs-WARNING **: Unable to create ~/.gnome2 directory: Not a directory
  Could not create per-user gnome configuration directory `99/.gnome2/': Not a directory
  mkdir: `99/.mozilla/extensions/{ec8030f7-c20a-464f-9b0e-13a3a9e97384}': Not a directory
  </code></pre>
  
  <p>I don't know enough about what's going on behind the scenes to troubleshoot this - why is the mkdir command being executed when firefox runs? Is it failing because I'm not a root user?</p>