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

NAME
     halt, reboot -- stopping and restarting the system

SYNOPSIS
     halt [-lnqu]
     reboot [-lnq]

DESCRIPTION
     The halt and reboot utilities flush the file system cache to disk, send
     all running processes a SIGTERM (and subsequently a SIGKILL) and, respec-
     tively, halt or restart the system.  The action is logged, including
     entering a shutdown record into the wtmp(5) file.

     When the system is halted with the halt command, the system is powered
     off.

     The options are as follows:

     -l      The halt or reboot is not recorded in the system log.  This
             option is intended for applications such as shutdown(8), that
             call reboot or halt and log this themselves.

     -n      The file system cache is not flushed.  This option should proba-
             bly not be used.

     -q      The system is halted or restarted quickly and ungracefully, and
             only the flushing of the file system cache is performed (if the
             -n option is not specified).  This option should probably not be
             used.

     -u      The system is halted up until the point of removing system power,
             but waits before removing power for 5 minutes so that an external
             UPS (uninterruptible power supply) can forcibly remove power.
             This simulates a dirty shutdown to permit a later automatic power
             on. OS X uses this mode automatically with supported UPSs in
             emergency shutdowns.

     Normally, the shutdown(8) utility is used when the system needs to be
     halted or restarted, giving users advance warning of their impending doom
     and cleanly terminating specific programs.

SIGTERM TO SIGKILL INTERVAL
     The SIGKILL will follow the SIGTERM by an intentionally indeterminate
     period of time.  Programs are expected to take only enough time to flush
     all dirty data and exit.  Developers are encouraged to file a bug with
     the OS vendor, should they encounter an issue with this functionality.

SEE ALSO
     wtmp(5), shutdown(8), sync(8)

HISTORY
     A reboot utility appeared in Version 6 AT&T UNIX.

BSD                              June 9, 1993                              BSD