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SHUTDOWN(8)		  BSD System Manager's Manual		   SHUTDOWN(8)

     shutdown, poweroff	-- close down the system at a given time

     shutdown [-] [-h |	-p | -r	| -k] [-o [-n]]	time [warning-message ...]

     The shutdown utility provides an automated	shutdown procedure for super-
     users to nicely notify users when the system is shutting down, saving
     them from system administrators, hackers, and gurus, who would otherwise
     not bother	with such niceties.

     The following options are available:

     -h	     The system	is halted at the specified time.

     -p	     The system	is halted and the power	is turned off (hardware	sup-
	     port required) at the specified time.

     -r	     The system	is rebooted at the specified time.

     -k	     Kick everybody off.  The -k option	does not actually halt the
	     system, but leaves	the system multi-user with logins disabled
	     (for all but super-user).

     -o	     If	one of the -h, -p or -r	options	are specified, shutdown	will
	     execute halt(8) or	reboot(8) instead of sending a signal to

     -n	     If	the -o option is specified, prevent the	file system cache from
	     being flushed by passing -n to halt(8) or reboot(8).  This	option
	     should probably not be used.

     time    Time is the time at which shutdown	will bring the system down and
	     may be the	case-insensitive word now (indicating an immediate
	     shutdown) or a future time	in one of two formats: +number,	or
	     yymmddhhmm, where the year, month,	and day	may be defaulted to
	     the current system	values.	 The first form	brings the system down
	     in	number minutes and the second at the absolute time specified.

	     Any other arguments comprise the warning message that is broad-
	     cast to users currently logged into the system.

     -	     If	`-' is supplied	as an option, the warning message is read from
	     the standard input.

     At	intervals, becoming more frequent as apocalypse	approaches and start-
     ing at ten	hours before shutdown, warning messages	are displayed on the
     terminals of all users logged in.	Five minutes before shutdown, or imme-
     diately if	shutdown is in less than 5 minutes, logins are disabled	by
     creating /var/run/nologin and copying the warning message there.  If this
     file exists when a	user attempts to log in, login(1) prints its contents
     and exits.	 The file is removed just before shutdown exits.

     At	shutdown time a	message	is written to the system log, containing the
     time of shutdown, the person who initiated	the shutdown and the reason.
     The corresponding signal is then sent to init(8) to respectively halt,
     reboot or bring the system	down to	single-user state (depending on	the
     above options).  The time of the shutdown and the warning message are
     placed in /var/run/nologin	and should be used to inform the users about
     when the system will be back up and why it	is going down (or anything

     A scheduled shutdown can be canceled by killing the shutdown process (a
     SIGTERM should suffice).  The /var/run/nologin file that shutdown created
     will be removed automatically.

     When run without options, the shutdown utility will place the system into
     single user mode at the time specified.

     Calling "poweroff"	is equivalent to running:

	   shutdown -p now

     /var/run/nologin  tells login(1) not to let anyone	log in

     The hours and minutes in the second time format may be separated by a
     colon (``:'') for backward	compatibility.

     kill(1), login(1),	wall(1), nologin(5), halt(8), init(8), reboot(8)

     The shutdown utility appeared in 4.0BSD.

BSD				 July 13, 2011				   BSD


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