shutdown — Halt, power-off or reboot the machine
shutdown [OPTIONS...] [now] [WALL...]
shutdown may be used to halt, power-off or reboot the machine.
The first argument should be the string now which however is ignored by this implementation. Optionally, this may be followed by a wall message to be sent to all logged-in users before going down.
The following options are understood:
Prints a short help text and exits.
Halt the machine.
Power-off the machine (the default).
Reboot the machine.
Equivalent to --poweroff, unless --halt is specified.
Don't halt, power-off, reboot, just write wall message.
Don't send wall message before halt, power-off, reboot.
On success 0 is returned, a non-zero failure code otherwise.
This is a legacy command available for compatibility only.
systemd(1), systemctl(1), halt(8), wall(1)