Originální popis anglicky:
reboot - reboot or enable/disable Ctrl-Alt-Del
Návod, kniha: Linux Programmer's Manual
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);
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
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 kernel command line
arguments (`reboot=...') to be either warm or cold, and either hard or through
the BIOS.
On success, zero is returned. On error, -1 is returned, and
errno is set
appropriately.
- EFAULT
- Problem with getting userspace data under
LINUX_REBOOT_CMD_RESTART2.
- EINVAL
- Bad magic numbers or flag.
- EPERM
- The calling process has insufficient privilege to call
reboot; the CAP_SYS_BOOT capability is required.
reboot is Linux specific, and should not be used in programs intended to
be portable.
sync(2),
bootparam(7),
capabilities(7),
ctrlaltdel(8),
halt(8),
reboot(8)
