Randomize your XFCE / LightDM Login Screen Wallpaper

HowTo: randomize LightDM / XFCE v4.x login screen wallpaper images.

For fans of the lightweight and highly configurable linux desktop environment XFCE, with it's default Greeter managed by LightDM, it's a frustrating fact of reality that there is no built in way to randomize the login screen image. This simple perl script and directory layout will provide that service using a cron job. The process will copy a random image file from a directory that contains a pool of images into a 'publish' directory; as background.jpg. XFCE then uses that image as the background for the login screen once configured.

Overview:

The basic premise of this procedure will be:

1. populate some directory with images you want to use for login backgrounds.
2. setup a cron job to run a script to copy a random image from the source directory into a publish directory
3. XFCE will use that image as the login screen background image.

TL;DR:

An example project for configuring randomized login screens for XFC can be found here

Single vs Multi User system and encrypted home directories:

• Single-user systems that do not use encrypted home directories you can use a directory within your home directory (i.e. /home/karl/Repositories/LoginWallpaper-XFCE-Variety).
• Multi-user systems that use a program like variety will need to use a user-group level directory location. (i.e. /opt/LoginWallpaper-XFCE-Variety)
• Single-user and Multi-user system that use encrypted home directories will need to use a user-group level directory location (i.e. /opt/LoginWallpaper-XFCE-Variety)

Generic setup

Examples will assume a multi-user system with encrypted home directories.

clone the example project to an appropriate directory:

# a global directory space
cd /opt
#
# clone the project
sudo git clone [e-mail]:karlredman/LoginWallpaper-XFCE-Variety.git
#
# set permissions on the project directory
sudo chown -R root:users LoginWallpaper-XFCE-Variety

add images to the image directory Variety

• Add whatever jpg images you deem worthy / safe to be on a login screen. For this example the images you add will go into /opt/LoginWallpaper-XFCE-Variety/Variety/.
• Do verify that your images belong to users group -change as necessary

run the project script to seed the publish directory

(i.e. /opt/LoginWallpaper-XFCE-Variety/Greeter/background.jpg)

• seed the file

cp $(/opt/LoginWallpaper-XFCE-Variety/mbin/print_random_file.pl /opt/LoginWallpaper-XFCE-Variety/Variety) /opt/LoginWallpaper-XFCE-Variety/Greeter/background.jpg

• verify the file exists -troubleshoot...

ls /opt/LoginWallpaper-XFCE-Variety/background.jpb

Configure LightDM Greeter via the GUI interface

• start the greeter config app using one of these methods:
  • via the GUI menu for LightDM GTK Greeter settings
  • name may vary based on linux desktop distribution
  • via command line

  sudo lightdm-gtk-greeter-settings

• Select Background->Image

• Set Image to <path>/background.jpg

  • i.e. /opt/LoginWallpaper-XFCE-Variety/Greeter/background.jpg
  • the name background.jpg is required

• Save the setting and exit the app

test and debug

If you are having issues try to run the command manually.

add cron job

• open cron in your default editor:

cron -e

• add the job (example)

# change to wallpaper every 10 min
*/10 * * * * cp $(/opt/LoginWallpaper-XFCE-Variety/mbin/print_random_file.pl /opt/LoginWallpaper-XFCE-Variety/Variety) /opt/LoginWallpaper-XFCE-Variety/Greeter/background.jpg

Using Variety as the image source:

Variety is a wallpaper background manager that is available for several linux distributions and is compatible with several desktop managers. One of the options variety offers is the ability to manage your login greeter image.

1. open variety preferences and navigate to customize tab
2. select Login Screen Support checkbox
3. specify the image directory (i.e. /opt/LoginWallpaper-XFCE-Variety/Variety)