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REBOOT(2)		      System Calls Manual		     REBOOT(2)

NAME
       reboot -- reboot	system or halt processor

LIBRARY
       Standard	C Library (libc, -lc)

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

       int
       reboot(int howto);

DESCRIPTION
       The  reboot()  system call reboots the system.  Only the	super-user may
       reboot 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  al-
       lows 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
		      fashion.

       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	parti-
		      tion.

       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 mi-
		      croprocessor 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  option, although their use may not be possible via
		      the reboot() system call.	 See ddb(4) for	more  informa-
		      tion.

       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	depre-
		      cated.

       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 sin-
		      gle-user shell on	the console.   RB_SINGLE  is  actually
		      interpreted  by  the init(8) program in the newly	booted
		      system.

       When no options are given (i.e.,	RB_AUTOBOOT is used),  the  system  is
       rebooted	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)).

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

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

SEE ALSO
       crash(8), halt(8), init(8), reboot(8), savecore(8), reboot(9)

HISTORY
       The reboot() system call	appeared in 4.0BSD.

FreeBSD	13.2			 July 10, 2018			     REBOOT(2)

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | SEE ALSO | HISTORY

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