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REBOOT(2)		   Linux Programmer's Manual		     REBOOT(2)

NAME
       reboot -	reboot or enable/disable Ctrl-Alt-Del

SYNOPSIS
       For libc4 and libc5 the library call and	the system call	are identical,
       and since kernel	version	2.1.30 there are symbolic names	LINUX_REBOOT_*
       for the constants and a fourth argument to the call:

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

       int reboot(int magic, int magic2, int flag, void	*arg);

       Under  glibc  some of the constants involved have gotten	symbolic names
       RB_*, and the library call is a 1-argument wrapper around  the  3-argu-
       ment system call:

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

       int reboot(int flag);

DESCRIPTION
       The reboot call reboots the system, or enables/disables the reboot key-
       stroke (abbreviated CAD,	since the default is Ctrl-Alt-Delete;  it  can
       be changed using	loadkeys(1)).

       This   system   call  will  fail	 (with	EINVAL)	 unless	 magic	equals
       LINUX_REBOOT_MAGIC1   (that   is,   0xfee1dead)	 and   magic2	equals
       LINUX_REBOOT_MAGIC2  (that  is, 672274793).  However, since 2.1.17 also
       LINUX_REBOOT_MAGIC2A  (that  is,	 85072278)  and	 since	 2.1.97	  also
       LINUX_REBOOT_MAGIC2B  (that  is,	 369367448) are	permitted as value for
       magic2.	(The hexadecimal values	of these  constants  are  meaningful.)
       The flag	argument can have the following	values:

       LINUX_REBOOT_CMD_RESTART
	      (RB_AUTOBOOT,  0x1234567).   The message `Restarting system.' is
	      printed, and a default restart is	performed immediately.	If not
	      preceded by a sync(2), data will be lost.

       LINUX_REBOOT_CMD_HALT
	      (RB_HALT_SYSTEM, 0xcdef0123; since 1.1.76).  The message `System
	      halted.' is printed, and the system is halted.  Control is given
	      to  the  ROM  monitor,  if  there	 is one.  If not preceded by a
	      sync(2), data will be lost.

       LINUX_REBOOT_CMD_POWER_OFF
	      (0x4321fedc;  since  2.1.30).   The  message  `Power  down.'  is
	      printed,	the  system  is	stopped, and all power is removed from
	      the system, if possible.	If not preceded	 by  a	sync(2),  data
	      will be lost.

       LINUX_REBOOT_CMD_RESTART2
	      (0xa1b2c3d4; since 2.1.30).  The message `Restarting system with
	      command '%s'' is printed,	 and  a	 restart  (using  the  command
	      string  given in arg) is performed immediately.  If not preceded
	      by a sync(2), data will be lost.

       LINUX_REBOOT_CMD_CAD_ON
	      (RB_ENABLE_CAD, 0x89abcdef).  CAD	is enabled.  This  means  that
	      the  CAD	keystroke will immediately cause the action associated
	      to LINUX_REBOOT_CMD_RESTART.

       LINUX_REBOOT_CMD_CAD_OFF
	      (RB_DISABLE_CAD, 0).  CAD	is disabled.  This means that the  CAD
	      keystroke	will cause a SIGINT signal to be sent to init (process
	      1), whereupon this process  may  decide  upon  a	proper	action
	      (maybe: kill all processes, sync,	reboot).

       Only the	super-user may use this	function.

       The  precise  effect  of	the above actions depends on the architecture.
       For the i386 architecture, the additional argument does not do anything
       at  present (2.1.122), but the type of reboot can be determined by ker-
       nel command line	arguments (`reboot=...') to be either  warm  or	 cold,
       and either hard or through the BIOS.

RETURN VALUE
       On  success,  zero is returned.	On error, -1 is	returned, and errno is
       set appropriately.

ERRORS
       EINVAL Bad magic	numbers	or flag.

       EPERM  A	non-root user attempts to call reboot.

CONFORMING TO
       reboot is Linux specific, and should not	be used	in  programs  intended
       to be portable.

SEE ALSO
       sync(2),	bootparam(7), ctrlaltdel(8), halt(8), reboot(8)

Linux 2.1.122			  1998-09-24			     REBOOT(2)

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | CONFORMING TO | SEE ALSO

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