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

     reboot, halt, fastboot, fasthalt -- stopping and restarting the system

     halt [-lNnpq] [-k kernel]
     reboot [-cdlNnpqr]	[-k kernel]
     fasthalt [-lNnpq] [-k kernel]
     fastboot [-dlNnpq]	[-k kernel]

     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 en-
     tering a shutdown record into the user accounting database.

     The options are as	follows:

     -c	     The system	will turn off the power	and then turn it back on if it
	     can.  If the power	down action fails, the system will halt	or re-
	     boot normally, depending on whether halt or reboot	was called.
	     At	the present time, only the ipmi(4) driver implements the power
	     cycle functionality and only on hardware with a BMC that supports
	     power cycling.  Unlike power off, the amount of hardware that
	     supports power cycling is small.

     -d	     The system	is requested to	create a crash dump.  This option is
	     supported only when rebooting, and	it has no effect unless	a dump
	     device has	previously been	specified with dumpon(8).

     -k	kernel
	     Boot the specified	kernel on the next system boot.	 If the	kernel
	     boots successfully, the default kernel will be booted on succes-
	     sive boots, this is a one-shot option.  If	the boot fails,	the
	     system will continue attempting to	boot kernel until the boot
	     process is	interrupted and	a valid	kernel booted.	This may
	     change in the future.

     -l	     The halt or reboot	is not logged to 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 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, such as with

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

     -p	     The system	will turn off the power	if it can.  If the power down
	     action fails, the system will halt	or reboot normally, depending
	     on	whether	halt or	reboot was called.

     -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

     -r	     The system	kills all processes, unmounts all filesystems, mounts
	     the new root filesystem, and begins the usual startup sequence.
	     After changing vfs.root.mountfrom with kenv(1), reboot -r can be
	     used to change the	root filesystem	while preserving kernel	state.
	     This requires the tmpfs(5)	kernel module to be loaded because
	     init(8) needs a place to store itself after the old root is un-
	     mounted, but before the new root is in place.

     The fasthalt and fastboot utilities are nothing more than aliases for the
     halt and reboot utilities.

     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.

     Replace current root filesystem with UFS mounted from /dev/ada0s1a:

	   kenv	vfs.root.mountfrom=ufs:/dev/ada0s1a
	   reboot -r

     This mechanism can	also be	used with NFS, with a caveat that it only
     works with	NFSv4, and requires a numeric IPv4 address:

	   kenv	vfs.root.mountfrom=nfs:
	   reboot -r

     kenv(1), getutxent(3), ipmi(4), boot(8), dumpon(8), nextboot(8),
     savecore(8), shutdown(8), sync(8)

     A reboot utility appeared in 4.0BSD.

BSD			       December	20, 2017			   BSD


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