Set a random wallpaper at startup in KDE Plasma

I’ve been a Openbox & Xfce user most of my GNU/Linux life. Only recently, I’ve started using KDE Plasma. In Openbox one can easily run a command via its autostart file to set a random wallpaper,

feh --no-fehbg --bg-scale --randomize path/to/the/wallpaper/directory/* &

Xfce makes it even easier as there already is an option to set a random wallpaper at startup in its settings.
In KDE Plasma, I was unable to find any option to set a random wallpaper at the session startup so I came up with a little hack to achieve this.
I keep all my wallpapers in $HOME/Pictures/Backgrounds directory and this hack is hard-coded to this particular path so if you keep your wallpapers in some other location, you’ll have to change this path accordingly. Any location is valid as long as you have write permissions for that location.
First thing that we need to do is create a hidden directory .default-background in $HOME/Pictures/Backgrounds directory. To do so, open your favorite terminal emulator and run,

mkdir $HOME/Pictures/Backgrounds/.default-background

Next, we need to create a link with the name of default_background.jpeg in this hidden directory to any wallpaper image file in the wallpaper directory. For this example I’m gonna pick a wallpaper image called there-is-no-cloud.jpeg,

ln -Pfn $HOME/Pictures/Backgrounds/there-is-no-cloud.jpeg $HOME/Pictures/Backgrounds/.default-background/default_background.jpeg

Now, right click on KDE Plasma desktop and select Configure Desktop and Wallpaper.... Next, under the Wallpaper tab, click on Add Image option and select the link, default_background.jpeg, that we have just created by navigating to the $HOME/Pictures/Backgrounds/.default-background directory. After adding this, select it and hit the Apply button to set it as the desktop wallpaper.
For our final step we need to create an empty file called random_background.sh in /etc/X11/xinit/xinitrc.d directory and make it executable,

sudo touch /etc/X11/xinit/xinitrc.d/random_background.sh
sudo chmod 755 /etc/X11/xinit/xinitrc.d/random_background.sh

Open this empty file as root or with sudo permissions in your favorite text-editor and paste the following code snippet into it,

#!/bin/sh

Backgrounds_Source="$HOME/Pictures/Backgrounds/"
Random_Background=$(find "$Backgrounds_Source" -type f -print0 | xargs -0 file --mime-type | grep -F 'image/' | cut -d ':' -f 1 | sort -R | head -n 1)
Background_Image="$HOME/Pictures/Backgrounds/.default-background/default_background.jpeg"

if [ -d "$Backgrounds_Source" ]; then

    if [ -n "$Random_Background" ]; then

	ln -Pfn "$Random_Background" "$Background_Image"

    fi
fi

Save the changes to the file.

That’s it! From now on, every time you log-in to a new session you’ll be greeted by a new wallpaper.

On certain GNU/Linux distributions, the directory /etc/X11/xinit/xinitrc.d might not be present. In such a scenario, you’ll need to create random_background.sh file in the /usr/local/bin directory and after pasting the above mentioned code into it, make it executable as described earlier. After doing that, you’ll need to create random_background.desktop file in either ~/.config/autostart directory or /etc/xdg/autostart directory and add the following snippet to it,

[Desktop Entry]
Type=Application
Name=Random_Wallpaper
TryExec=/usr/local/bin/random_background.sh
Exec=/usr/local/bin/random_background.sh
StartupNotify=false
NoDisplay=true

After saving the file, you’ll need to enable/add Random_Wallpaper to your desktop session startup list. The procedure varies between different desktop environments but here is how you can navigate to autostart setting on a few popular desktop environments,

KDE => System Settings > Startup and Shutdown > Autostart
Xfce => Menu > Settings > Settings Manager > Session and Startup > Application Autostart
LXQt => Menu > Preferences > LXQt Settings > Session Settings

Just in case, someone was curious about that there-is-no-cloud.jpeg wallpaper,

There Is No Cloud

Don’t hesitate to contact me if you have any question or confusion regarding this article or anything else on the blog.


 Date: February 13, 2022
 Tags:  wallpaper KDE
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