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!!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 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. !!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(2) 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)
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reboot(2)
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Man2r
syscalls(2)
Hardware
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