reboot man page on Archlinux

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REBOOT(2)		   Linux Programmer's Manual		     REBOOT(2)

       reboot - reboot or enable/disable Ctrl-Alt-Del

       /* 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 cmd, 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 cmd);

       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 cmd argument can have the following values:

	      (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).

	      (RB_ENABLE_CAD,  0x89abcdef).   CAD is enabled.  This means that
	      the CAD keystroke will immediately cause the  action  associated

	      (RB_HALT_SYSTEM,	0xcdef0123;  since Linux 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.

	      (RB_KEXEC, 0x45584543, since Linux 2.6.13).   Execute  a	kernel
	      that has been loaded earlier with kexec_load(2).	This option is
	      available only if the kernel was configured with CONFIG_KEXEC.

	      (RB_POWER_OFF, 0x4321fedc; since	Linux  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.

	      (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.

	      (0xa1b2c3d4;  since Linux 2.1.30).  The message "Restarting sys‐
	      tem with command '%s'" is printed, and a restart (using the com‐
	      mand string given in arg) is performed immediately.  If not pre‐
	      ceded by a sync(2), data will be lost.

	      (RB_SW_SUSPEND, 0xd000fce1; since Linux 2.5.18).	The system  is
	      suspended	 (hibernated)  to disk.	 This option is available only
	      if the kernel was configured with CONFIG_HIBERNATION.

       Only the superuser may call 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  ker‐
       nel  command-line  arguments  ("reboot=...") to be either warm or cold,
       and either hard or through the BIOS.

       For the values of cmd that stop or restart  the	system,	 a  successful
       call  to	 reboot()  does not return.  For the other cmd values, zero is
       returned on success.  In all cases, -1  is  returned  on	 failure,  and
       errno is set appropriately.

       EFAULT Problem	   with	     getting	 user-space	data	 under

       EINVAL Bad magic numbers or cmd.

       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),

       This  page  is  part of release 3.65 of the Linux man-pages project.  A
       description of the project, and information about reporting  bugs,  can
       be found at

Linux				  2013-12-28			     REBOOT(2)

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