Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages


home | help
REBOOT(2)		    BSD	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	   Interpreted by the bootstrap	program	itself,	causing	it to
		   prompt on the console as to what file should	be booted.
		   Normally, the system	is booted from the file
		   "xx(0,0)kernel", where xx is	the default disk name, without
		   prompting for the file name.

     RB_DFLTROOT   Use the compiled in root device.  Normally, the system uses
		   the device from which it was	booted as the root device if
		   possible.  (The default behavior is dependent on the	abil-
		   ity 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_POWEROFF   After halting, the shutdown code will do what it can	to
		   turn	off the	power.	This requires hardware support.

     RB_INITNAME   An option allowing the specification	of an init program
		   (see	init(8)) other than /sbin/init to be run when the sys-
		   tem reboots.	 This switch is	not currently available.

     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 op-
		   tions have different	meaning	if combined with this option,
		   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	useful
		   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) variable.

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

     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.

BSD			      September	18, 2015			   BSD


Want to link to this manual page? Use this URL:

home | help