Kommandogenerator för poweroff

`shutdown` schedules a shutdown (with optional time and wall message) and is the canonical tool. `poweroff` is a shortcut equivalent to `shutdown -h now` followed by removing power. For a timed or warned shutdown, use `shutdown -h +5 'message'`.

Almost never in normal use. It skips flushing filesystem buffers, so anything written in the last few seconds can be lost. Reserve it for recovery environments where you have already unmounted or where the filesystem is read-only.