title: notify-send not working (in script) executed from udev
body: <p>I want a notification in desktop that a particular USB device is inserted.Hence the following is the udev rule.</p>
  
  <pre><code>KERNEL=="sd*",SUBSYSTEMS=="usb",ACTION=="add",RUN+="/home/username/Desktop/notify_script"
  </code></pre>
  
  <p>notify_script is as follows</p>
  
  <pre><code>#!/bin/sh  
  su username -c 'notify-send "USB Inserted"'  
  echo USB_inserted &gt;&gt; /home/username/Desktop/test_file 
  </code></pre>
  
  <p>Problem :</p>
  
  <p>The above script works perfectly if it is executed as root from command line but,  notify-send in script is not working if executed from udev.</p>
  
  <p>Question:</p>
  
  <p>How to make notify-send work from udev? or 
  Is there any other way by which I can achieve notification ?<br>
  Is it possible to invoke any GUI from udev?</p>
  
  <p>Thank you.    </p>