NAME

halt, reboot, poweroff - 中止系統運行  

SYNOPSIS

/sbin/halt [-n] [-w] [-d] [-f] [-i] [-p]
/sbin/reboot [-n] [-w] [-d] [-f] [-i]
/sbin/poweroff [-n] [-w] [-d] [-f] [-i]  

描述

Halt 將系統正在關機的信息寫入 /var/log/wtmp 文件，然后通知內核停止重啟或關機系統。如果 halt 或 reboot 是在系統 沒有 運行在運行級別 0 或 6 ，系統將調用 shutdown(8) 命令（使用參數 -h 或 -r ）。  

選項

-n

在關機或重啟之前不對系統緩存進行同步。

-w

不真正重啟或關機，而僅僅將關機信息寫入 wtmp （在 /var/log/wtmp 文件里）。

-d

不記錄此次關機情況。當使用 -n 參數時隱含 -d。

-f

強制執行 halt 或 reboot 而不去調用 shutdown(8)。

-i

在關閉或重啟系統之前關閉所有網絡界面。

-p

當關閉系統時執行關閉電源操作。當以 poweroff 方式調用 halt 時，此為缺省參數。

DIAGNOSTICS

If you're not the superuser, you will get the message `must be superuser'.  

注意

在先前的 sysvinit 發布中，reboot 和 halt 不能直接調用。從版本 2.74 開始，當系統不是運行在運行級別0或6的時侯，執行 halt 和 reboot 后實際調用的是 shutdown(8) 。這就意味著如果在當前運行級別的環境中無法找到
 halt 或 reboot 的時候（比如，在 /var/run/utmp  還沒有正確初始化的時候），將會調用 shutdown，這個結果也許非你所想。如果你想做一此硬的 halt 或 reboot，那么使用 -f 參數。

作者

Miquel van Smoorenburg, miquels@cistron.nl  

參見

shutdown(8), init(1)  

#p#

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) 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.  

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.

EFAULT

Problem with getting userspace data under LINUX_REBOOT_CMD_RESTART2.

CONFORMING TO

reboot 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)