Rotating wallpapers in GNOME

I recently found a nice stash of cool wallpapers (all starwars themed naturally). Essentially just google imgur starwars wallpapers if you’re interested. Now, I found my new stash of wallpapers very pleasing but I wasn’t about to sit and manually switch them when I felt like it. Hell no, this calls for automation.

I started out with this:

#!/bin/sh

BG_DIR=/home/linus/Pictures/wallpapers
next=$(ls -1 $BG_DIR | shuf -n 1)
gsettings set org.gnome.desktop.background picture-uri "file://$BG_DIR/$next"

Nice. Worked like a charm. Now let’s just stuff that in cron with a 10 minute rotation and we should be golden. Like this:

*/10 * * * * sh ~/bin/wallpaper_rotator.sh

Nope. Errors.

((process:2356646): dconf-WARNING **: 13:51:01.194: failed to commit changes to dconf: Cannot autolaunch D-Bus without X11 $DISPLAY)

Turns out, gsettings needs some env variables to be set in order to know what display to operate on etc.

This solution actually took me a bit to find so I thought I’d share it again to help anyone in the future. Here is what you need to feed into cron:

*/10 * * * * env DISPLAY=:0 DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/1000/bus sh ~/bin/wallpaper_rotator.sh

Notice in particular the variables DISPLAY and DBUS_SESSION_BUS_ADDRESS. Take special note of the uid present in the middle of the DBUS_SESSION_BUS_ADDRESS. In my example it’s 1000 which is my users id on this computer. To find yours you can just cat /etc/passwd.

That’s all.

// Liq