Background
I have created a script that changes my wallpaper periodically. The script works perfectly fine when I run it from bash, but having to manually run it on every startup is becoming annoying, so I decided I would automate the process using systemd.
Scripts
Following is the script that changes the wallpaper:
targetDir="/home/mypc/Pictures/Wallpapers"
function get_next_photo() {
# Returns a random file form targetdir
files=( "$targetDir"/* )
echo "${files[RANDOM % ${#files[@]}]}"
}
function set_background() {
# Takes an absolute file path as argument. Need * for spaces in path
bg="$*"
echo "Setting background to $bg"
dconf write "/org/gnome/desktop/background/picture-uri" "'file://$bg'"
}
while :
do
background=$(get_next_photo)
echo "Next background is $background"
set_background $background
sleep 5m
done
And this is the systemd service I created for it, located in /etc/systemd/system/background-changer.service:
[Unit]
Description=Periodically changes the background wallpaper, taking random images from the Pictures/wallpapers folder
[Service]
ExecStart=/bin/bash /home/mypc/background_changer.sh
[Install]
WantedBy=default.target
Problem
The problem is that once I start the job using systemd the wallpaper never changes.
After checking with sudo systemd status background-changer.service, this is what I got:
$ sudo systemctl status background-changer.service
● background-changer.service - Periodically changes the background wallpaper, taking random images from the Pictures/wallpapers folder
Loaded: loaded (/etc/systemd/system/background-changer.service; disabled; vendor preset: enabled)
Active: active (running) since Mon 2023-01-09 13:17:32 CET; 7min ago
Main PID: 14196 (bash)
Tasks: 2 (limit: 18936)
Memory: 596.0K
CPU: 16ms
CGroup: /system.slice/background-changer.service
├─14196 /bin/bash /home/mypc/background_changer.sh
└─17655 sleep 5m
ene 09 13:17:32 systemd[1]: Started Periodically changes the background wallpaper, taking random images from the Pictures/wallpapers folder.
ene 09 13:17:32 bash[14196]: Next background is /home/mypc/Pictures/Wallpapers/jonatan-pie-3l3RwQdHRHg-unsplash.jpg
ene 09 13:17:32 bash[14196]: Setting background to /home/mypc/Pictures/Wallpapers/jonatan-pie-3l3RwQdHRHg-unsplash.jpg
ene 09 13:17:32 bash[14198]: error: Cannot autolaunch D-Bus without X11 $DISPLAY
ene 09 13:22:32 bash[14196]: Next background is /home/mypc/Pictures/Wallpapers/jonatan-pie-3l3RwQdHRHg-unsplash.jpg
ene 09 13:22:32 bash[14196]: Setting background to /home/mypc/Pictures/Wallpapers/jonatan-pie-3l3RwQdHRHg-unsplash.jpg
ene 09 13:22:32 bash[17652]: error: Cannot autolaunch D-Bus without X11 $DISPLAY
The last line specifically caught my attention:
error: Cannot autolaunch D-Bus without X11 $DISPLAY
I have searched for some time now how to fix this, but every solution I find is widely different. I went from reinstalling graphic drivers, to password managers with stuff in between, but nothing works:
Can someone help me understand why ?
