In older days that I used to run Fluxbox, in order to be able to shutdown my computer I need to allow passwordless root access via sudo to the command
shutdown by running viedit and doing the appropriate changes.
Also when the computer shutdown my computer is perfmormed over terminal via the shutdown command, root access is needed.
But modern Desktop GUI implementations such as KDE/GNOME/LXDE/XFCE etc etc the shutdown is by default rootless (no root password is required). And I wonder how theese desktop GUIS manage to "perform"/notify the kernel that the computer is shutting down without the need of root access?
