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


NAME

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


SYNOPSIS

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


DESCRIPTION

     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
             support required, otherwise the system is halted) 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 is specified, shutdown will execute
             halt(8) or reboot(8) instead of sending a signal to init(8).

     -n      If the -o is specified, prevent the file system cache from being
             flushed by passing -n option 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 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.  +number may be specified in units other than
             minutes by appending the corresponding suffix: "s", "sec", "m",
             "min".  "h", "hour".

             If an absolute time is specified, but not a date, and that time
             today has already passed, shutdown will assume that the same time
             tomorrow was meant.  (If a complete date is specified which has
             already passed, shutdown will print an error and exit without
             shutting the system down.)

     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
     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 /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.
     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 else).

     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


FILES

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


EXAMPLES

     Reboot the system in 30 minutes and display a warning message on the
     terminals of all users currently logged in:

           # shutdown -r +30 "System will reboot"


BACKWARD COMPATIBILITY

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


SEE ALSO

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


HISTORY

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

DragonFly 5.9-DEVELOPMENT        June 9, 2020        DragonFly 5.9-DEVELOPMENT

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