mirror of https://github.com/mkerrisk/man-pages
181 lines
5.1 KiB
Groff
181 lines
5.1 KiB
Groff
.\" Copyright (c) 1998 Andries Brouwer (aeb@cwi.nl), 24 September 1998
|
|
.\"
|
|
.\" Permission is granted to make and distribute verbatim copies of this
|
|
.\" manual provided the copyright notice and this permission notice are
|
|
.\" preserved on all copies.
|
|
.\"
|
|
.\" Permission is granted to copy and distribute modified versions of this
|
|
.\" manual under the conditions for verbatim copying, provided that the
|
|
.\" entire resulting derived work is distributed under the terms of a
|
|
.\" permission notice identical to this one.
|
|
.\"
|
|
.\" Since the Linux kernel and libraries are constantly changing, this
|
|
.\" manual page may be incorrect or out-of-date. The author(s) assume no
|
|
.\" responsibility for errors or omissions, or for damages resulting from
|
|
.\" the use of the information contained herein. The author(s) may not
|
|
.\" have taken the same level of care in the production of this manual,
|
|
.\" which is licensed free of charge, as they might when working
|
|
.\" professionally.
|
|
.\"
|
|
.\" Formatted or processed versions of this manual, if unaccompanied by
|
|
.\" the source, must acknowledge the copyright and authors of this work.
|
|
.\" Modified, 27 May 2004, Michael Kerrisk <mtk.manpages@gmail.com>
|
|
.\" Added notes on capability requirements
|
|
.\"
|
|
.TH REBOOT 2 2008-02-11 "Linux" "Linux Programmer's Manual"
|
|
.SH NAME
|
|
reboot \- reboot or enable/disable Ctrl-Alt-Del
|
|
.SH 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: */
|
|
.sp
|
|
.B #include <unistd.h>
|
|
.br
|
|
.B #include <linux/reboot.h>
|
|
.sp
|
|
.BI "int reboot(int " magic ", int " magic2 ", int " cmd ", void *" arg );
|
|
.sp
|
|
/* 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: */
|
|
.sp
|
|
.B #include <unistd.h>
|
|
.br
|
|
.B #include <sys/reboot.h>
|
|
.sp
|
|
.BI "int reboot(int " cmd );
|
|
.SH DESCRIPTION
|
|
The
|
|
.BR 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
|
|
.BR loadkeys (1)).
|
|
.PP
|
|
This system call will fail (with
|
|
.BR EINVAL )
|
|
unless
|
|
.I magic
|
|
equals
|
|
.B LINUX_REBOOT_MAGIC1
|
|
(that is, 0xfee1dead) and
|
|
.I magic2
|
|
equals
|
|
.B LINUX_REBOOT_MAGIC2
|
|
(that is, 672274793).
|
|
However, since 2.1.17 also
|
|
.B LINUX_REBOOT_MAGIC2A
|
|
(that is, 85072278)
|
|
and since 2.1.97 also
|
|
.B LINUX_REBOOT_MAGIC2B
|
|
(that is, 369367448)
|
|
and since 2.5.71 also
|
|
.B LINUX_REBOOT_MAGIC2C
|
|
(that is, 537993216)
|
|
are permitted as value for
|
|
.IR magic2 .
|
|
(The hexadecimal values of these constants are meaningful.)
|
|
The
|
|
.I cmd
|
|
argument can have the following values:
|
|
.TP
|
|
.B 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
|
|
.BR sync (2),
|
|
data will be lost.
|
|
.TP
|
|
.B 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
|
|
.BR sync (2),
|
|
data will be lost.
|
|
.TP
|
|
.B 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
|
|
.BR sync (2),
|
|
data will be lost.
|
|
.TP
|
|
.B 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
|
|
.IR arg )
|
|
is performed immediately.
|
|
If not preceded by a
|
|
.BR sync (2),
|
|
data will be lost.
|
|
.TP
|
|
.B LINUX_REBOOT_CMD_CAD_ON
|
|
(RB_ENABLE_CAD, 0x89abcdef).
|
|
CAD is enabled.
|
|
This means that the CAD keystroke will immediately cause
|
|
the action associated with
|
|
.BR LINUX_REBOOT_CMD_RESTART .
|
|
.TP
|
|
.B LINUX_REBOOT_CMD_CAD_OFF
|
|
(RB_DISABLE_CAD, 0).
|
|
CAD is disabled.
|
|
This means that the CAD keystroke will cause a
|
|
.B SIGINT
|
|
signal to be
|
|
sent to init (process 1), whereupon this process may decide upon a
|
|
proper action (maybe: kill all processes, sync, reboot).
|
|
.LP
|
|
Only the superuser may call
|
|
.BR reboot ().
|
|
.LP
|
|
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.
|
|
.SH "RETURN VALUE"
|
|
For the values of
|
|
.I cmd
|
|
that stop or restart the system,
|
|
a successful call to
|
|
.BR reboot ()
|
|
does not return.
|
|
For the other
|
|
.I cmd
|
|
values, zero is returned on success.
|
|
In all cases, \-1 is returned on failure, and
|
|
.I errno
|
|
is set appropriately.
|
|
.SH ERRORS
|
|
.TP
|
|
.B EFAULT
|
|
Problem with getting userspace data under
|
|
.BR LINUX_REBOOT_CMD_RESTART2 .
|
|
.TP
|
|
.B EINVAL
|
|
Bad magic numbers or \fIcmd\fP.
|
|
.TP
|
|
.B EPERM
|
|
The calling process has insufficient privilege to call
|
|
.BR reboot ();
|
|
the
|
|
.B CAP_SYS_BOOT
|
|
capability is required.
|
|
.SH "CONFORMING TO"
|
|
.BR reboot ()
|
|
is Linux-specific,
|
|
and should not be used in programs intended to be portable.
|
|
.SH "SEE ALSO"
|
|
.BR sync (2),
|
|
.BR bootparam (7),
|
|
.BR capabilities (7),
|
|
.BR ctrlaltdel (8),
|
|
.BR halt (8),
|
|
.BR reboot (8)
|