REBOOT(8) BSD System Manager's Manual REBOOT(8)
reboot, halt - stopping and restarting the system
halt [-dnpq] reboot [-dnq]
The halt and reboot utilities flush the filesystem cache to disk, run the system shutdown script, send all running processes a SIGHUP, SIGTERM and one or more SIGKILL, and, respectively, halt or restart the system. The action is logged, including entering a shutdown record into the login ac- counting file. The options are as follows: -d Causes system to create a dump before rebooting. This option is useful for debugging system dump procedures or capturing the state of a corrupted or misbehaving system. See savecore(8) for information on how to recover this dump. -n Prevent filesystem cache from being flushed. This option should probably not be used. -p Causes the system to power down, if it is being halted, and the hardware supports automatic power down. -q Quick. The system is halted or restarted quickly and ungraceful- ly, and only the flushing of the filesystem cache is performed. 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.
/etc/rc.shutdown script which is run at shutdown time by /etc/rc /var/db/host.random where 2 KiB entropy are stored before reboot(2)
reboot(2), utmp(5), boot_i386(8), boot_sparc(8), rc.shutdown(8), savecore(8), shutdown(8), sync(8)
A reboot command appeared in Version 6 AT&T UNIX. MirBSD #10-current August 7, 2017 1