内容简介
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>%uA0
#include <linux/reboot.h>
int reboot(int%uA0magic, int%uA0magic2, int%uA0flag, 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>%uA0
#include <sys/reboot.h>
int reboot(int%uA0flag)
描述
The%uA0reboot() call reboots the system, or enables/disables the reboot keystroke (abbreviated CAD, since the default is Ctrl-Alt-Delete it can be changed usingloadkeys(1)).This system call will fail (with EINVAL) unless%uA0magic%uA0equals LINUX_REBOOT_MAGIC1 (that is, 0xfee1dead) and%uA0magic2%uA0equals 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%uA0magic2. (The hexadecimal values of these constants are meaningful.) The%uA0flag%uA0argument can have the following values:
| 标签 | 描述 |
|---|---|
| LINUX_REBOOT_CMD_RESTART | |
| %uA0 | (RB_AUTOBOOT, 0x1234567). The message ‘Restarting system.’ is printed, and a default restart is performed immediately. If not preceded by a%uA0sync(2), data will be lost. |
| LINUX_REBOOT_CMD_HALT | |
| %uA0 | (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 async(2), data will be lost. |
| LINUX_REBOOT_CMD_POWER_OFF | |
| %uA0 | (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%uA0sync(2), data will be lost. |
| LINUX_REBOOT_CMD_RESTART2 | |
| %uA0 | (0xa1b2c3d4 since 2.1.30). The message ‘Restarting system with command ’%s’’ is printed, and a restart (using the command string given in%uA0arg) is performed immediately. If not preceded by a%uA0sync(2), data will be lost. |
| LINUX_REBOOT_CMD_CAD_ON | |
| %uA0 | (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 | |
| %uA0 | (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). |
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.
返回值
On success, zero is returned. On error, -1 is returned, and%uA0errno%uA0is set appropriately.错误
| 标签 | 描述 |
|---|---|
| EFAULT | Problem with getting userspace data under LINUX_REBOOT_CMD_RESTART2. |
| EINVAL | Bad magic numbers or%uA0flag. |
| EPERM | The calling process has insufficient privilege to call%uA0reboot() theCAP_SYS_BOOTꃊpability is required. |