NAME
halt, reboot, poweroff - 中止系统运行
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 将系统正在关机的信息写入 /var/log/wtmp 文件，然后通知内核停止重启或关机系统。如果 halt 或 reboot 是在系统 没有 运行在运行级别 0 或 6 ，系统将调用 shutdown(8) 命令（使用参数 -h 或 -r ）。
选项
- -n
- 在关机或重启之前不对系统缓存进行同步。
- -w
- 不真正重启或关机，而仅仅将关机信息写入 wtmp （在 /var/log/wtmp 文件里）。
- -d
- 不记录此次关机情况。当使用 -n 参数时隐含 -d。
- -f
- 强制执行 halt 或 reboot 而不去调用 shutdown(8)。
- -i
- 在关闭或重启系统之前关闭所有网络界面。
- -p
- 当关闭系统时执行关闭电源操作。当以 poweroff 方式调用 halt 时，此为缺省参数。
DIAGNOSTICS
If you're not the superuser, you will get the message `must be superuser'.
注意
在先前的 sysvinit 发布中，reboot 和 halt 不能直接调用。从版本 2.74 开始，当系统不是运行在运行级别0或6的时侯，执行 halt 和 reboot 后实际调用的是 shutdown(8) 。这就意味着如果在当前运行级别的环境中无法找到
halt 或 reboot 的时候（比如，在 /var/run/utmp 还没有正确初始化的时候），将会调用 shutdown，这个结果也许非你所想。如果你想做一此硬的 halt 或 reboot，那么使用 -f 参数。
作者
Miquel van Smoorenburg, miquels@cistron.nl
参见
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)
