This script automates the process of setting an image or color in GNOME Display Manager 3 background which comes by default with Ubuntu or Pop OS versions 20.04 Focal Fossa, 20.10 Groovy Gorilla and 21.04 Hirsute Hippo.
This script wont work with any older version of Ubuntu or Pop OS because they have a different way of dealing with gdm settings.
It also won't work if your system is set to a custom gdm3 theme. You will have to reset to the default configuration of gdm3 before using the script.
This tool was made specifically to work with Ubuntu or Pop OS 20.04, 20.10 and 21.04 as it now bundles all configuration files inside a .gresource file.
If you are going to set an image file that has spaces in its file name or folders, remember to scape them with backslashes.
I HAVE DISABLED THE GUI APP REPO BECASE IT WAS CAUSING THE NEW UBUNTU 21.10 TO CRASH. SORRY FOR ANY INCOVENIENCE.
First, you will need to install libglib2.0-dev-bin with sudo apt install libglib2.0-dev-bin
Then, you can download the script with the command below:
wget github.com/hyoaru/change-gdm-background/raw/master/change-gdm-background
And set it as an executable with chmod +x change-gdm-background
Run the script with root privileges such as sudo ./change-gdm-background /path/to/image.
If you see a message login image sucessfully changed, then, when you restart gdm or reboot your
computer, your gdm background should be covered with the image you selected.
You can restore your original gdm theme any time with sudo ./change-gdm-background --restore.
Now you can change that annoying purple color to any color you like. Just type sudo ./change-gdm-background \#yourhexcode and voilá, you changed it. Your color hex format should
be of six characters like \#407294 or three characters like \#6ac.
if you use two or more monitors you may see a streched image through the displays as if they were one screen. This is the default behavior of GDM3 when dealing with multiple displays.
I found a way to configure GDM to work in other modes like mirror or even single display here, avoiding the joining of them.
If you feel this tool was useful and want to show some appreciation, you can donate via https://ko-fi.com/thiggy01.