This brief tutorial will show you how to change the background wallpaper in Ubuntu 13.04 LightDM login screen. By default it has a dynamic background which will change to reflect the selected user’s desktop background. So that change your user desktop wallpaper will change the LightDM background too.
If you want a different LightDM background wallpaper to user’s desktop background wallpaper, follow the step below:
1. Hit Ctrl+Alt+T to open a terminal, all work will be done in this terminal window. First run command to get root privilege. You’ll be prompt to input user password:
2. Execute following command to allow the user “lightdm” to create a connection to the X server:
3. Now in this terminal switch to the user “lightdm”:
su lightdm -s /bin/bash
4. Turn off the dynamic background for LightDM, after that you get a fixed LightDM background.
gsettings set com.canonical.unity-greeter draw-user-backgrounds 'false'
5. Finally change the login screen background by:
gsettings set com.canonical.unity-greeter background 'PATH-TO-IMAGE'
If you want to change the wallpaper again, in a new terminal window do steps 1, 2, 3 and finally step 5 in same window.