Using plasma-apply-wallpaperimage in cron job

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1

I have a script to set the desktop wallpaper image that essentially does the following:

plasma-apply-wallpaperimage $filename

The script works fine if I run it manually. However, if I run it as a cron job, it returns the error:

An error occurred while attempting to set the Plasma wallpaper:
Not connected to D-Bus server

How can one change the desktop wallpaper using a cron job?

1 Like
2

It’s probably because the cron job does not have access to your Dbus session. I thought Plasma already comes with a slideshow function, why not use that?

3

It’s probably because the cron job does not have access to your Dbus session.

Is there any way to get that information and pass it to the script?

I thought Plasma already comes with a slideshow function, why not use that?

Right now that is what I am doing…

Ultimately, though, I would like to do this all using a script that I can transfer from one computer to another without having to do extra steps.

4

I believe that wallpaper setting are stored in ~/.config/plasma-org.kde.plasma.desktop-appletsrc.
Double checking, mine shows my different wallpaper settings across both my monitors and for all of my Activities.

5

You could try a systemd service and timer that runs under your user session. That would likely be able to change it.

1 Like
6

Thanks @claydoh and @Justin
Modifying ~/.config/plasma-org.kde.plasma.desktop-appletsrc did the trick!
A systemd service sounds like an overengineered solution for this :slight_smile: and I am not savvy enough to come up with that anyway.
But eventually I decided to go with the simpler solution of just using the Slideshow mode. My script will fetch a wallpaper image every night and place it in a directory.

2 Likes
7

For reference, the systemd solution would look something like this. The systemd timer essentially replaces the cron job:
~/.config/systemd/user/update-desktop.timer:

[Unit]
Description=Periodically update the desktop background

[Timer]
# Trigger when hour and minute are 0 (i.e. midnight)
OnCalendar=0 0 * * *

[Install]
WantedBy=timers.target

~/.config/systemd/user/update-desktop.service:

[Unit]
Description=Update the desktop background with the latest image from somewhere

[Service]
Type=oneshot
# Your script that fetches the image and sets it
ExecStart=/path/to/update-desktop.sh

Once you’ve created these two files, you just need to run
systemctl --user enable update-desktop.timer
to enable it.

1 Like
8

put the following at the beginning of your cron script:

export DBUS_SESSION_BUS_ADDRESS="unix:path=/run/user/$(id -u)/bus"
export DISPLAY=":0"
export LC_TIME=C
export LC_NUMERIC=C