Ubuntu – 18.04 – Cannot change the background color of the LOCK screen, not the Login screen

18.04gnome-shelllock-screenthemes

Good evening,

I'm trying to change some of the colours of my login screen in my Ubuntu 18.04. I followed some questions here on AskUbuntu, and edited my css files at /usr/share/gnome-shell/theme/gnome-shell.css (I'm using that configuration) – Specifically, I changed the values of .lockDialogGroup to a nicer dark gray.

My login screen is indeed now a nice dark gray instead of that hellish purple.

However, if I lock my computer without shutting down the machine, I still get a different purple gradient, which I haven't managed to change. I'm serching around but since I don't even know what to call this "behind-the-shield" screen, I can't find relevant results.

I suspect the login screen and the lock screen are two different managers altogether.

Here's a short mp4 video of me literally filming my screen, to make you understand which color I'm trying to change:

https://imgur.com/8aBWhd4

EDIT: There seems to be a discrepancy between my first-after-boot login screen, and my login-after-locking screen.

first Login screen after boot:

After-lock login screen:

Best Answer

Edit the file /usr/share/xsessions/ubuntu-communitheme-snap.desktop and change the "ubuntu-communitheme" text to "myct" (change anything, not necessarily "myct") in the line starting with Exec=

sudo -H gedit /usr/share/xsessions/ubuntu-communitheme-snap.desktop

[Desktop Entry]
Name=Ubuntu with communitheme snap
Comment=This session logs you into Ubuntu
Exec=env GNOME_SHELL_SESSION_MODE=myct /snap/communitheme/current/session
TryExec=/snap/communitheme/current/session
Type=Application
DesktopNames=communitheme:ubuntu:GNOME
X-Ubuntu-Gettext-Domain=gnome-session-3.0

create a file named myct.json in the directory /usr/share/gnome-shell/modes/ with below content.

{
    "parentMode": "user",
    "stylesheetName": "myct.css",
    "enabledExtensions": ["ubuntu-dock@ubuntu.com", "ubuntu-appindicators@ubuntu.com"]
}

Create a text file named myct.css in the directory /usr/share/gnome-shell/theme/

sudo touch /usr/share/gnome-shell/theme/myct.css

Open the file and paste the below content

sudo -H gedit /usr/share/gnome-shell/theme/myct.css

Content:

@import url("/snap/communitheme/current/share/gnome-shell/theme/Communitheme/gnome-shell.css");

#lockDialogGroup {
  background-color: magenta; }

Reboot and then lock the screen to see your preferred color.

Related Solutions

Ubuntu – How to change the purple background color of the lock screen on Ubuntu 17.10

From these steps here, you can change both the image and the background colour:

Move your favorite image to /usr/share/backgrounds:
- It's better to move the image you want to set as login background to system pictures folder: /usr/share/backgrounds. To do so, open terminal via Ctrl+Alt+T, then either run command:
```
sudo cp /PATH/TO/IMAGE /usr/share/backgrounds/
```
Edit the css file that define GDM login background:
- Open terminal (Ctrl+Alt+T) and run command to edit file /etc/alternatives/gdm3.css, which is linked to /usr/share/gnome-shell/theme/gdm3.css:
```
# Make backup first before editing
sudo cp /etc/alternatives/gdm3.css /etc/alternatives/gdm3.css.bakup
sudo nano /etc/alternatives/gdm3.css
```

When the file opens, go to menu (right after ‘Save’ button) -> find and find out following section:

#lockDialogGroup {
  background: #2c001e url(resource:///org/gnome/shell/theme/noise-texture.png);
  background-repeat: repeat; }

change the lines into:

#lockDialogGroup {
   background: #000000 url(file:///usr/share/backgrounds/Aardvark_Wallpaper_Grey_4096x2304.png);
   background-repeat: no-repeat;
   background-size: cover;
   background-position: center; }

Replace Aardvark_Wallpaper_Grey_4096x2304.png with your picture file name, and or change the hex colour code ##2c001e to the color of your choice.Here I used black.

Lockscreen background:

Note: Backup all files before changing them

Ubuntu – How to customize Lock Screen theme in Ubuntu 20.04

In a fresh install of Ubuntu 20.04, the default shell theme.. and lock screen both are configured to use the css file

Yaru/gnome-shell.css which is inside the /usr/share/gnome-shell/theme/Yaru/gnome-shell-theme.gresource

this is configured in the file /usr/share/gnome-shell/modes/ubuntu.json

{
    "parentMode": "user",
    "stylesheetName": "Yaru/gnome-shell.css",
    "themeResourceName": "theme/Yaru/gnome-shell-theme.gresource",
    "debugFlags": ["backtrace-crashes-all"],
    "enabledExtensions": ["ubuntu-dock@ubuntu.com", "ubuntu-appindicators@ubuntu.com", "desktop-icons@csoriano"]
}

So, you can pointout what ever .gresource file you want to use and the corresponding gnome-shell.css

for example, If I want Yaru-dark theme, I can simply point out like this by editing the file /usr/share/gnome-shell/modes/ubuntu.json

Take Backup of the file /usr/share/gnome-shell/modes/ubuntu.json before editing

{
    "parentMode": "user",
    "stylesheetName": "Yaru-dark/gnome-shell.css",
    "themeResourceName": "theme/Yaru/gnome-shell-theme.gresource",
    "debugFlags": ["backtrace-crashes-all"],
    "enabledExtensions": ["ubuntu-dock@ubuntu.com", "ubuntu-appindicators@ubuntu.com", "desktop-icons@csoriano"]
}

Please note that Default shell theme and lock screen uses same file.. so If you want Yaru shell theme for the desktop session.. you need to install it as a local theme which is another topic.

I have not tried with full path of the .gresource file.. in the line

"themeResourceName": "theme/Yaru/gnome-shell-theme.gresource",

this means.. theme/Yaru/gnome-shell-theme.gresource is a relative path of the base /usr/share/gnome-shell

Best Answer

Related Solutions

Ubuntu – How to change the purple background color of the lock screen on Ubuntu 17.10

Ubuntu – How to customize Lock Screen theme in Ubuntu 20.04

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