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NAME    [Toc]    [Back]

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

SYNOPSIS    [Toc]    [Back]

       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    [Toc]    [Back]

       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 hexadecimal values of these  constants  are  meaningful.)
       The flag argument can have the following values:

       LINUX_REBOOT_CMD_RESTART    [Toc]    [Back]
	      (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    [Toc]    [Back]
	      (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    [Toc]    [Back]
	      (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    [Toc]    [Back]
	      (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    [Toc]    [Back]
	      (RB_ENABLE_CAD, 0x89abcdef).  CAD is enabled.  This  means  that
	      the  CAD	keystroke will immediately cause the action associated

       LINUX_REBOOT_CMD_CAD_OFF    [Toc]    [Back]
	      (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 kernel
 command line arguments (`reboot=...') to be either  warm  or  cold,
       and either hard or through the BIOS.

RETURN VALUE    [Toc]    [Back]

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

ERRORS    [Toc]    [Back]

       EINVAL Bad magic numbers or flag.

       EPERM  A non-root user attempts to call reboot.

CONFORMING TO    [Toc]    [Back]

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

SEE ALSO    [Toc]    [Back]

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

Linux 2.1.122			  1998-09-24			     REBOOT(2)
[ Back ]
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