Running shell Script via Crontab

Use > cron.log 2>&1 to have the cronjob write its output to a file, so that you could see the error messages it produces. (Some cron daemons automatically write the output to syslog when mail is not available; yours apparently doesn't.)

Most likely the problem is that 'gsettings set' works via D-Bus (the session bus, specifically, not the system bus) and usually requires either one of DBUS_SESSION_BUS_ADDRESS or XDG_RUNTIME_DIR environment variables to be present (depending on setup).

First of all, though:

• If your system has systemctl --user available, consider using its .timer units instead, as most likely your graphical desktop already forwards the necessary environment variables into your systemd per-user manager.

• If you don't want to deal with .timer and .service units, you could use systemd-run from crontab to start the script in the correct environment:

  00 20 * * * systemd-run --user ~/Bilder/Hintergründe/.background_skript/background_night.sh 

If you want to do everything through cron:

1. Run echo $DBUS_SESSION_BUS_ADDRESS in a terminal window and check what path is shown.

2. If the bus path was shown as /run/user/XXX/bus, its location is static – you can just put one of the following at the top of your cronjob (or, export them at the beginning of your script):

   XDG_RUNTIME_DIR="/run/user/XXX" DBUS_SESSION_BUS_ADDRESS="unix:path=/run/user/XXX/bus" 

   (Usually XDG_RUNTIME_DIR is enough to cover D-Bus as well as various other components.)

3. If the bus path is shown as /tmp/dbus-XXXXXXX, it's dynamic – you need to store the value somewhere on every login:

   1. Edit ~/.xprofile or ~/.xinitrc (whichever applies) to store the environment in files:

      echo "$DBUS_SESSION_BUS_ADDRESS" > /tmp/dbus.env echo "$DISPLAY" > /tmp/display.env 

   2. Edit your script to load the environment from files:

      export DBUS_SESSION_BUS_ADDRESS=$(< /tmp/dbus.env) export DISPLAY=$(< /tmp/display.env)