title: How to use change desktop wallpaper using Python in Ubuntu 14.04 (with Unity)
body: <p>I tried this code:</p>
  
  <pre><code>import os
  os.system("gsettings set org.gnome.desktop.background picture-uri file:///home/user/Pictures/wallpapers/X")
  </code></pre>
  
  <p>where <code>user</code> is my name and <code>X</code> is the picture.</p>
  
  <p>But instead of changing the background to the given picture, it set the default Ubuntu wallpaper.</p>
  
  <p>What am I doing wrong?</p>