| SHUTDOWN(8) | System Manager's Manual | SHUTDOWN(8) | 
shutdown —
| shutdown | [ -Ddfhknprvxz] [-bbootstr] time
      [message ... | -] | 
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-dshutdown will pass the -d
      flag to reboot(8) or
      halt(8) to request a kernel
      core dump. If neither the -h or
      -r flags are specified, then
      -d also implies -r.-fshutdown arranges, in the manner of
      fastboot(8), for the file
      systems not to be checked on reboot.-h-k-k option does not
      actually halt the system, but leaves the system multi-user with logins
      disabled (for all but super-user).-n-p-r-v-v
      to reboot(8) or
      halt(8).-x-x to
      reboot(8) or
      halt(8).-z-z to
      reboot(8) or
      halt(8).-Dshutdown from detaching from the tty with
      fork(2)/
      exit(3).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 may be defaulted to the current system values. 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, it defaults to 1900 for
      years between 69 and 99, or 2000 for years between 0 and 68. A leading
      zero in the “yy” value is not
    optional.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.
shutdown command was originally written by Ian
  Johnstone for UNSW's modified AT&T UNIX 6th Edn,
  modified, and then incorporated in 4.1BSD.
| September 12, 2016 | NetBSD 9.4 |