How to change lockscreen and login wallpaper with Arctica greeter?

I recently installed a fresh 21.10 Ubuntu MATE, and I'm having issue changing the login wallpaper. I read here that I'm supposed to use the Dconf editor, but that didn't work for me (ran both as root & user). I also tried to use my current background by enabling "draw user background", but that was no-go either.

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Not sure how it goes in 21.10, but you can install LightDM back by following (which was written for previous release) link below:

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I had this question before and this worked well for me when Utsuro explained it to me. Just be careful to follow the directions and heed the warnings.

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What about the lockscreen wallpaper? The gradient gets a little tiring.

I think there's now an option for this in:

  • Ubuntu MATE panel layout: Brisk Menu -> search for Screensaver.
  • Traditional panel layout: System menu -> Preferences -> Look and Feel -> Screensaver.

In the dialog that pops up, go to the bottom of the dialog and there should be an option for the wallpaper shown when the screen locker displays the password prompt. Choose appropriate wallpaper.

(This feature is new to MATE 1.24.)

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(This feature is new to MATE 1.24.)

Are you intending to refer to the desktop version in Ubuntu-Mate 20.04.2 LTS? Because I seem to be missing that option despite the system reporting that Mate desktop version in System Monitor.

The question was asked about 21.04 (Impish), not 20.04 (Focal). Focal only has MATE 1.24.0; Hirsute and Impish have 1.24.1 or later, which contained the feature addition I was talking about. When I wrote it was something new to 1.24, I didn't remember at the moment which point release made the change; it was 1.24.1, which Focal doesn't have.

(Yes, I know I should have made that clearer.)

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I don't think the message in System Monitor even has the last zero which is why I was getting excited. It's nice to see new features coming in that make sense evolutionarily. Not sure if I'm willing to give up my LTS install early for them yet.

Thanks! I just changed my lock screen wallpaper, and it worked. I wouldn't have thought of that unless you told me. How new is this?

Maybe the desktop/menu entry should be changed to "screensaver and lockscreen" or "screen lock settings". I never thought of checking the screensaver settings.

So that's one down.

I understand that reverting to Slick is an option (as suggested by @Norbert_X) to fix the ability to change login wallpaper, but right now , I'll just stick to Arctica since that's where Ubuntu MATE's going. And besides, I still got 2 more Linux distros in this old laptop (and probably more soon).

Since I already explained this in relatively scant detail above, I'll say it again here, but go into more detail this time:

This feature was noted in the file which describes new features in the MATE Screensaver version 1.24.1 (available at https://pub.mate-desktop.org/releases/1.24/mate-screensaver-1.24.1.news):

That file was last modified on the 20th of August 2020. A quick check of the Ubuntu Packages Database (https://packages.ubuntu.com/groovy/mate-screensaver) reveals that Ubuntu MATE 20.10 (Groovy Gorilla) was the first Ubuntu MATE release to include the MATE Screensaver 1.24.1, and thus was the first to include this feature. Sorry, 20.04 users!

Found this posting via search. I'm currently on 21.04, but have been unable to change my login image using the artica greeter for several releases.

I followed the instructions provided by gordon, and this does change the background image displayed on the login page after lock screen has been in effect. So that much is good.

However, this does not affect the background image on the login page displayed on initial system startup. Following a suggestion from another post, I tried using dconf-editor to change the setting /org/ArcticaProject/arctica-greeter/background to "/usr/share/backgrounds/cosmos/blue-marble-west.jpg". The default setting is "/usr/share/backgrounds/ubuntu-mate-common/Green-Wall-Logo.png". Unfortunately, when the system starts up, it is still displaying the default image.

Has anyone successfully changed this? Thanks.

The arctica greeter background is /usr/share/backgrounds/ubuntu-mate-common/Green-Wall-Logo.png

Move this file to Green-Wall-Logo-bak.png, then make a symbolic link in this folder named Green-Wall-Logo.png to the desired background.

In my case, I wanted to use Blue-Wall-Logo.png which is in the folder /usr/share/backgrounds/ubuntu-mate-colours-blue so the link is made:

sudo ln -s ../ubuntu-mate-colours-blue/Blue-Wall-Logo.png Green-Wall-Logo.png

(This works in Ubuntu MATE 21.04)

Edit: Changed "Backup" to "Move this file".

@Spyder, thanks for this. Your method works to change the background image on the login page during system startup and if the user logs out. I'm going to file a bug report on this, as I don't see why the greeter uses the setting I mentioned if the system is locked, but doesn't use the setting upon system startup or if the user logs out.

Issue opened here: artica-greeter should use specified background image on the login page · Issue #25 · ArcticaProject/arctica-greeter · GitHub

Hi @guyr,
similar issue has already been reported on Github: arctica-greeter does not honor gsettings changes · Issue #17 · ArcticaProject/arctica-greeter · GitHub.
The solution is already mentioned in current thread: How to change lockscreen and login wallpaper with Arctica greeter? - #3 by bornagainpenguin.
Arctica greeter settings are stored in /usr/share/glib-2.0/schemas/30_ubuntu-mate.gschema.override file. Inspect it, and you'll find arctica greeter section and different settings, including path to the background file. You may edit this file directly OR create your own override file. I recommend the latter approach.

  1. Create file /usr/share/glib-2.0/schemas/40_arctica-greeter.gschema.override .
  2. Contents: arctica greeter section header and desired background filename. Use original file as an example.
    [org.ArcticaProject.arctica-greeter]
    background='<your background here>'
  3. Run sudo glib-compile-schemas /usr/share/glib-2.0/schemas/ to recompile schemas.
  4. Relogin.

Hope this helps

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@ironfoot Thanks for the followup. Before posting, I had tried @gordon 's solution. It only changes the login background for lock screen; it does not change the background shown upon system startup or when I logoff.

Your solution works. I closed the issue I had opened as a dup of the one you identify. I read that one and it helped me understand why changing background via dconf-editor does not work (background drawing is owned by user lightdm.)

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Why do people keep considering the Unlock Screen prompt to be a login prompt? :confused:

(EDIT: I now understand the confusion; I was just a little abrasive the day I wrote this.)

When you lock the screen, you don't log out in any way, shape or form. All that locking the screen does is display a big, opaque window over the top of everything else, and require that you enter your credentials in order for that window to go away. Locking the screen does not physically log you out.

As such, the lock screen wallpaper has nothing to do with Arctica or whatever display manager you're using; the screensaver program actually draws the Unlock Screen prompt and the wallpaper. Only when you log in, or when you Switch Users, will Arctica be involved in the picture.

If you don't believe me, lock the screen, then press a key to get the Unlock Screen dialog to appear. Press Ctrl-Alt-F1, log in to the same user whose screen you locked, and type pkill mate-screensav. (The full name, mate-screensaver, does not work due to a pkill bug.) Then press Ctrl-Alt-F7 to get back to the GUI, and the screen locker will have disappeared and you'll be "logged back in"! Wow! Who'd have expected that?


TL;DR: I'm not trying to offend anybody; what I'm trying to say is that the issue is being made more complicated by a misunderstanding about the hierarchy of the Linux desktop environment.

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This did help! Wish there's a GUI solution, but I'll take what I can get. Thanks!!

I'll mark this as the solution.

Edit: wish @gordon's solution for the lockscreen can also be marked, but it seems to be one-at-a-time thing only.

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Why do people keep considering the Unlock Screen prompt to be a login prompt?

Fair question, and since I am included in that group, I'll provide my perspective. What you say makes sense, and helps me understand why setting the unlock background to what I wanted didn't change the background for the login page. So, thanks for clarifying.

In answer to your question: Upon system bootup, I'm presented with a login screen that shows my username, and prompts me for a password. When I lock the screen and ask to unlock, I'm presented with a dialog that ... shows my username, and prompts me for a password. So, the system is doing exactly the same thing to unlock that it did to login. And that's why I equate the two. I imagine I'm in good company.

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