Changing wallpapers in GNOME 3.4 could be a bit confusing initially because there are three different wallpaper settings and there is no simple, convenient and uniform way to change these various wallpapers. There is a wallpaper setting for your desktop, another one for the login screen, and yet another one for the lock screen. This article explains how to set each wallpaper on a Debian 7.0 (Wheezy) system.


The next three sections explain the steps required to change each wallpaper. A different image is used for each wallpaper. In the commands and screenshots that appear in this article, the following three images are used.

  1. NATURE-JEDSpringInYellowAndRed_1920x1200.jpg
  2. NATURE-SkyStone_1920x1200.jpg
  3. NATURE-TheDivide_1920x1200.jpg

These images were obtained from Permission is granted to copy and use these images by the creators of these images. See the COPYRIGHT.txt file for more details.

Remember to update the paths to images appearing in the steps below to the paths of the images on your file system that you want to set as the wallpaper.

Change desktop wallpaper

The desktop wallpaper is the easiest one to change. You can just double-click an image to open it with the GNOME Image Viewer and then select 'Set as Desktop Background' from the 'Image' menu.

Alternatively, the desktop background can also be changed with a command as follows.

gsettings set org.gnome.desktop.background picture-uri file:///home/fabhax/wallpapers/NATURE-JEDSpringInYellowAndRed_1920x1200.jpg

You should be able to see the updated desktop wallpaper as soon as you execute the command. No service needs to be restarted.

Screenshot of updated desktop wallpaper
Updated desktop wallpaper

Change login wallpaper

To change the login wallpaper, first become a superuser by running the su command and entering the root password. Then invoke a new shell as the user that displays the GNOME 3 login screen. This is 'Debian-gdm' on Debian GNU/Linux 7.0 (Wheezy).

su - Debian-gdm -s /bin/bash

On other Linux systems, this user ma be 'gdm' instead, so you may have to replace 'Debian-gdm' with 'gdm' in the above command on other Linux systems. To determine which user is displaying the GNOME 3 login screen, run the following command before logging in to your desktop while the login screen is displayed: ps -ef | grep gnome-session. The first column of the output displays the user running the login screen. If it's a numeric ID, look for that ID in /etc/passwd to determine the username.

Finally, in this shell, run the following commands.

`dbus-launch | sed 's/^/export /'`
gsettings set org.gnome.desktop.background picture-uri file:///home/fabhax/wallpapers/NATURE-SkyStone_1920x1200.jpg

You can see the new login wallpaper after you restart GNOME display manager. Press Ctrl + Alt + F1 to go into tty1, log in as root, and restart 'gdm3' with the following command.

/etc/init.d/gdm3 restart
Screenshot of updated login wallpaper
Updated login wallpaper

Change lock screen wallpaper

To change the lock screen wallpaper, create an XML file in /usr/share/images/desktop-base directory with the path to the image to be used as the lock screen wallpaper as shown below.

      <size width="1920" height="1200">/home/fabhax/wallpapers/NATURE-TheDivide_1920x1200.jpg</size>

You might want to edit the attributes of the size element in the XML to match the image size. You may see other XML files in the same directory to see what these XML files look like. If we assume that your XML file with the path to the image for your lock screen wallpaper is saved as /usr/share/images/desktop-base/lockscreen.xml, then you have to run the following command so that /etc/alternatives/desktop-background.xml is updated as a symbolic link to your new XML file.

ln -sf /usr/share/images/desktop-base/lockscreen.xml /etc/alternatives/desktop-background.xml

You can see the new login wallpaper after you restart GNOME display manager. Press Ctrl + Alt + F1 to go into tty1, log in as root, and restart 'gdm3' with the following command.

/etc/init.d/gdm3 restart

Log in to your desktop, lock screen by pressing Ctrl + Alt + L. Now, when you try to unlock your screen, you should see the updated lock screen wallpaper.

Screenshot of updated lock screen wallpaper
Updated lock screen wallpaper

Play vintage DOS games with DOSBox

Sunday, July 29, 2012

Are you old enough to miss the vintage DOS games like Dangerous Dave, Digger, etc. that won't run on a modern operating system like Microsoft Windows or Linux? If you do, you don't have to. There is a little cool free software called DOSBox that lets you run MS-DOS programs on your modern operating system.

DOSBox is an emulator that emulates an IBM PC compatible computer running MS-DOS. As a result, you can run MS-DOS programs including the old games that were written for MS-DOS environment. It can be downloaded from its download page and installed. On Debian, Ubuntu or similar Linux systems, DOSBox can be installed simply by running the following command:

aptitude install dosbox

Once it is installed and run, it displays a Z prompt. Now, you may mount any directory on your computer file's system as a drive on DOSBox. For example, if you are on Windows and you want to mount a folder called C:\Games on DOSBox, you need to execute the following command at the Z prompt in DOSBox:

MOUNT C C:\Games

It's no different on Linux as can be seen in the screenshot below.

Screenshot of mounting C drive on DOSBox
Mounting C drive on DOSBox running on a Linux system

Once you have a C drive, you can can use DOS commands to move from one directory to another and execute DOS programs just like you would do in a real MS-DOS system. Press Alt + Enter to go into and out of full screen.

The old DOS games can be downloaded from one of many websites on the web that maintain an archive of these games. has a good collection.

Screenshot of Dangerous Dave running on DOSBox
Dangerous Dave running on DOSBox
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