reboot (8) ( FreeBSD man: Команды системного администрирования )
reboot (8) ( Linux man: Команды системного администрирования )
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: */
int reboot(int magic, int magic2, int cmd, 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: */
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)
and since 2.5.71 also
LINUX_REBOOT_MAGIC2C
(that is, 537993216)
are permitted as value for
magic2.
(The hexadecimal values of these constants are meaningful.)
The
cmd
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 aq%saq" 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 with
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 superuser may call
reboot().
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
For the values of
cmd
that stop or restart the system,
a successful call to
reboot()
does not return.
For the other
cmd
values, zero is returned on success.
In all cases, -1 is returned on failure, and
errno
is set appropriately.
ERRORS
EFAULT
Problem with getting userspace data under
LINUX_REBOOT_CMD_RESTART2.
EINVAL
Bad magic numbers or cmd.
EPERM
The calling process has insufficient privilege to call
reboot();
the
CAP_SYS_BOOT
capability is required.
CONFORMING TO
reboot()
is Linux-specific,
and should not be used in programs intended to be portable.
This page is part of release 3.14 of the Linux
man-pages
project.
A description of the project,
and information about reporting bugs,
can be found at
http://www.kernel.org/doc/man-pages/.
