centos man page for shutdown

SHUTDOWN(8)							     shutdown							       SHUTDOWN(8)

NAME
       shutdown - Halt, power-off or reboot the machine

SYNOPSIS
       shutdown [OPTIONS...] [TIME] [WALL...]

DESCRIPTION
       shutdown may be used to halt, power-off or reboot the machine.

       The first argument may be a time string (which is usually "now"). Optionally, this may be followed by a wall message to be sent to all
       logged-in users before going down.

       The time string may either be in the format "hh:mm" for hour/minutes specifying the time to execute the shutdown at, specified in 24h clock
       format. Alternatively it may be in the syntax "+m" referring to the specified number of minutes m from now.  "now" is an alias for "+0",
       i.e. for triggering an immediate shutdown. If no time argument is specified, "+1" is implied.

       Note that to specify a wall message you must specify a time argument, too.

       If the time argument is used, 5 minutes before the system goes down the /run/nologin file is created to ensure that further logins shall
       not be allowed.

OPTIONS
       The following options are understood:

       --help
	   Prints a short help text and exits.

       -H, --halt
	   Halt the machine.

       -P, --poweroff
	   Power-off the machine (the default).

       -r, --reboot
	   Reboot the machine.

       -h
	   Equivalent to --poweroff, unless --halt is specified.

       -k
	   Do not halt, power-off, reboot, just write wall message.

       --no-wall
	   Do not send wall message before halt, power-off, reboot.

       -c
	   Cancel a pending shutdown. This may be used cancel the effect of an invocation of shutdown with a time argument that is not "+0" or
	   "now".

EXIT STATUS
       On success, 0 is returned, a non-zero failure code otherwise.

SEE ALSO
       systemd(1), systemctl(1), halt(8), wall(1)

systemd 208															       SHUTDOWN(8)