osx man page for reboot

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,
     respectively, 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 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.

     -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 func-
     tionality.

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

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

BSD
								   June 9, 1993 							       BSD