How to create a screen shot of the GDM login screen on Ubuntu Hardy

This blog pts explains how to create a screen shot of the currently running X11 GDM login screen (the graphics login screen at system startup) on Ubuntu Hardy.

1. Install ImageMagick for the image file format conversion below:

   $ sudo apt-get install imagemagick

2. Create a helper script:

   $ echo 'DISPLAY=:0 XAUTHORITY=/var/lib/gdm/:0.Xauth xwd -root' >/tmp/shot.sh

3. Make sure your login screen is active (log out or reboot the machine, and wait until you see the login screen).
4. Log in in text mode (by pressing Ctrl-Alt-F1), or using SSH.
5. Create the screen shot by running

   $ sudo bash /tmp/shot.sh >/tmp/shot.xwd

6. You can log in now (by pressing Ctrl-AltF7 first to get back to the GDM login screen).
7. Convert the screen shot to JPEG and/or PNG:

   $ convert -quality 50 /tmp/shot.xwd /tmp/shot.jpg
   $ convert /tmp/shot.xwd /tmp/shot.png

8. View the screen shot in your favourite image viewer.