NAME
     shutdown - close down the system at a given time

SYNOPSIS
     shutdown [-] [-fhkrn] time [warning-message ...]

DESCRIPTION
     Shutdown 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:

     -f    Shutdown arranges, in the manner of fastboot(8),  for the file sys-
           tems not to be checked on reboot.

     -h    The system is halted at the specified time when shutdown execs
           halt(8).

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

     -n    Prevent the normal sync(2) before stopping.

     -r    Shutdown execs reboot(8) at the specified time.

     time  Time is the time at which shutdown will bring the system down and
           may be the word now (indicating an immediate shutdown) or specify 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.

     warning-message
           Any other arguments comprise the warning message that is broadcast
           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 /etc/nologin and copying the warning message there.  If this
     file exists when a user attempts to log in, login(8) prints its contents
     and exits.  The file is removed just before shutdown exits.

     At shutdown time a message is written in the system log, containing the
     time of shutdown, who initiated the shutdown and the reason.  A terminate
     signal is then sent to init to bring the system down to single-user state
     (depending on above options).  The time of the shutdown and the warning
     message are placed in /etc/nologin and should be used to inform the users
     about when the system will be back up and why it is going down (or any-
     thing else).

FILES
     /etc/nologin  tells login not to let anyone log in
     /fastboot     tells rc(8) not to run fsck when rebooting

SEE ALSO
     wall(1),  fastboot(8),  halt(8),  login(8),  reboot(8)

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

HISTORY
     The shutdown command appeared in 4.0BSD.