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REBOOT(2)		  FreeBSD System Calls Manual		     REBOOT(2)

     reboot -- reboot system or	halt processor

     Standard C	Library	(libc, -lc)

     #include <unistd.h>
     #include <sys/reboot.h>

     reboot(int	howto);

     The reboot() system call reboots the system.  Only	the super-user may re-
     boot a machine on demand.	However, a reboot is invoked automatically in
     the event of unrecoverable	system failures.

     The howto argument	is a mask of options; the system call interface	allows
     the following options, defined in the include file	<sys/reboot.h>,	to be
     passed to the new kernel or the new bootstrap and init programs.

     RB_AUTOBOOT    The	default, causing the system to reboot in its usual

     RB_ASKNAME	    Normally the system	only prompts the user if the loader
		    specified root file	system has an error.  This flag	forces
		    it to always prompt	the user for the root partition.

     RB_DFLTROOT    Use	the compiled in	root device.  Normally,	the system
		    uses the device from which it was booted as	the root de-
		    vice if possible.  (The default behavior is	dependent on
		    the	ability	of the bootstrap program to determine the
		    drive from which it	was loaded, which is not possible on
		    all	systems.)

     RB_DUMP	    Dump kernel	memory before rebooting; see savecore(8) for
		    more information.

     RB_HALT	    The	processor is simply halted; no reboot takes place.
		    This option	should be used with caution.

     RB_POWERCYCLE  After halting, the shutdown	code will do what it can to
		    turn off the power and then	turn the power back on.	 This
		    requires hardware support, usually an auxiliary micropro-
		    cessor that	can sequence the power supply.	At present
		    only the ipmi(4) driver implements this feature.

     RB_POWEROFF    After halting, the shutdown	code will do what it can to
		    turn off the power.	 This requires hardware	support.

     RB_KDB	    Load the symbol table and enable a built-in	debugger in
		    the	system.	 This option will have no useful function if
		    the	kernel is not configured for debugging.	 Several other
		    options have different meaning if combined with this op-
		    tion, although their use may not be	possible via the
		    reboot() system call.  See ddb(4) for more information.

     RB_NOSYNC	    Normally, the disks	are sync'd (see	sync(8)) before	the
		    processor is halted	or rebooted.  This option may be use-
		    ful	if file	system changes have been made manually or if
		    the	processor is on	fire.

     RB_REROOT	    Instead of rebooting, unmount all filesystems except the
		    one	containing currently-running executable, and mount
		    root filesystem using the same mechanism which is used
		    during normal boot,	based on vfs.root.mountfrom kenv(1)

     RB_RDONLY	    Initially mount the	root file system read-only.  This is
		    currently the default, and this option has been depre-

     RB_SINGLE	    Normally, the reboot procedure involves an automatic disk
		    consistency	check and then multi-user operations.
		    RB_SINGLE prevents this, booting the system	with a single-
		    user shell on the console.	RB_SINGLE is actually inter-
		    preted by the init(8) program in the newly booted system.

     When no options are given (i.e., RB_AUTOBOOT is used), the	system is re-
     booted from file "kernel" in the root file	system of unit 0 of a disk
     chosen in a processor specific way.  An automatic consistency check of
     the disks is normally performed (see fsck(8)).

     If	successful, this call never returns.  Otherwise, a -1 is returned and
     an	error is returned in the global	variable errno.

     [EPERM]		The caller is not the super-user.

     crash(8), halt(8),	init(8), reboot(8), savecore(8)

     The reboot() system call appeared in 4.0BSD.

FreeBSD	13.0			 July 10, 2018			  FreeBSD 13.0


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