lock desktop + lock screen wallpaper?

Question

I have a high school lab running Ubuntu 18.04. How can I lock down the wallpaper and lock screen images so students can't change the image to something obnoxious ?

I was hoping it was a simple file change removing write permissions.

Thanks ~~

Answer 1

Locking the wallpaper requires as per the GNOME Admin help guide

• setting the wallpaper
• making a locks directory under the keyfiles directory, then
• defining what you want locked, and finally
• updating with sudo dconf update

Answer 2

I work in a school and I used the following commands to block screen wallpaper:

First: Block Control Panel to prevent students changes configurations like keyboard language, user password, etc...

sudo chmod 750 /usr/bin/gnome-control-center

Second: Make an immutable dconf file for student user to prevent Right click > Set as Wallpaper make effects:

sudo chattr +i /home/student/.config/dconf/user

With that you will successfully block wallpaper changes and prevent user settings modifications.

Check that the users you want to block are not sudoers, as in that case they can revert these changes using sudo.