Shut down after offline updates with PackageKit from command line

Question

When PackageKit has updates fetched for installation and you use the Gnome GUI to shut down the machine, it is possible to set a checkbox to install updates before shut down. How can this be accomplished from command line without root? Example purpose: automating the execution of custom commands before shut down.

Answer 1

# This will force fetching repository data and updates
pkcon get-updates
pkcon update --only-download

dbus-send --system --type=method_call --print-reply \
  --dest=org.freedesktop.PackageKit \
  /org/freedesktop/PackageKit \
  org.freedesktop.PackageKit.Offline.Trigger \
  string:power-off

if pkcon offline-get-prepared; then
  systemctl reboot
else
  systemctl poweroff
fi

If you remove the dbus-send command and replace the if block by systemctl reboot, the system will reboot instead.