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RedHat 9 (Linux i386) - man page for reboot (redhat section 2)

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-argument 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 keystroke  (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  hexa-
       decimal values of these constants are meaningful.)  The flag argument can have the follow-
       ing 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 immedi-
	      ately.  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 archi-
       tecture, the additional argument does not do anything at present (2.1.122), but	the  type
       of  reboot  can be determined by kernel 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)


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