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

NAME
     halt, reboot – stopping and restarting the system

SYNOPSIS
     halt [-lNnq]
     reboot [-lNnq]

DESCRIPTION
     The halt and reboot utilities flush the file system cache to disk, send
     all running processes a SIGTERM (and subsequently a SIGKILL) and,
     respectively, halt or restart the system.  The action is logged,
     including entering a shutdown record into the user accounting database.

     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 logged to the system log.  This option
             is intended for applications such as shutdown(8), that call halt
             or reboot and log this themselves.

     -N      The file system cache is not flushed during the initial process
             clean-up, however the kernel level reboot(2) is still processed
             with a sync.  This option can be useful for performing a
             “best-effort” reboot when devices might be unavailable.  This can
             happen when devices have been disconnected.

     -n      The file system cache is not flushed.  This option should
             probably 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.

     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
     getutxent(3), wtmp(5), shutdown(8), sync(8)

HISTORY
     A reboot utility appeared in 4.0BSD.

macOS 15.2                       June 6, 2023                       macOS 15.2