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

NAME
     shutdown - close down the system at a given time

SYNOPSIS
     shutdown [-Ddfhknprvxz] [-b bootstr] time [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.

     Available friendlinesses:

     -b bootstr  The given bootstr is passed to reboot(8) for the benefit of
                 those systems that can pass boot arguments to the firmware.
                 Currently, this only affects sun3 and sparc machines.

     -d          shutdown will pass the -d flag to reboot(8) or halt(8) to
                 request a kernel core dump.  If neither the -h nor -r flags
                 are specified, then -d also implies -r.

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

     -h          The system is halted at the specified time, using halt(8).

     -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).

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

     -p          The system is powered down at the specified time, using
                 poweroff(8).  If the powerdown fails, or the system does not
                 support software powerdown, the system will simply halt
                 instead.

     -r          The system is rebooted at the specified time, using
                 reboot(8).

     -v          To enable verbose messages on the console, pass -v to
                 reboot(8) or halt(8).

     -x          To enable debugging messages on the console, pass -x to
                 reboot(8) or halt(8).

     -z          To silence some shutdown messages on the console, pass -z to
                 reboot(8) or halt(8).

     -D          Prevents shutdown from detaching from the tty with fork(2) /
                 exit(3).

     time        The time at which shutdown will bring the system down and may
                 be the word now or a future time in one of two formats:
                 +number, or [[[[[cc]yy]mm]dd]hh]mm, where the century, year,
                 month, day, and hour are two digit decimal values, which may
                 be defaulted to the current system values.  The two digit
                 (decimal, even with a leading zero) minute field is required
                 in this form.  The first form brings the system down number
                 minutes from the current time; the second brings the system
                 down at the absolute time specified.  If the century is not
                 specified, but the year is, the century defaults to 2000 (cc
                 = 20, the 21st century) for years between 20 and 99, or 2100
                 for years between 0 and 19.  A leading zero in the yy value
                 (as with all the others) is not optional.

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

     -           If - is supplied as the only argument after the time, the
                 warning message is read from the standard input.

BEHAVIOR
     At intervals, becoming more frequent as apocalypse approaches and
     starting at ten hours before shutdown, warning messages are displayed on
     the terminals of all users logged in.  Five minutes before shutdown, or
     immediately 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(1) 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.  Next a
     message is printed announcing the start of the system shutdown hooks.
     Then the shutdown hooks in /etc/rc.shutdown are run, and a message is
     printed indicating that they have completed.  After a short delay,
     shutdown runs halt(8) or reboot(8), or sends a terminate signal to
     init(8) to bring the system down to single-user mode, depending on the
     choice of options.

     The time of the shutdown and the warning message are placed in
     /etc/nologin and should be used to tell the users why the system is going
     down, when it will be back up, and to share any other pertinent
     information.

FILES
     /etc/nologin                      Tells login(1) not to let anyone log in
     /fastboot                         Tells rc(8) not to run fsck(8) when
                                       rebooting
     /etc/rc.shutdown                  System shutdown commands

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

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

HISTORY
     A shutdown command was originally written by Ian Johnstone for UNSW's
     modified Version 6 AT&T UNIX, modified, and then incorporated in 4.1BSD.

NetBSD 10.99                   February 14, 2023                  NetBSD 10.99