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 sym-
     bolic 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

     Under glibc some of the constants involved have gotten  sym-
     bolic  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));


     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:

          (RB_AUTOBOOT, 0x1234567).  The message `Restarting sys-
          tem.'  is  printed,  and a default restart is performed
          immediately.  If not preceded by a sync(2),  data  will
          be lost.

          (RB_HALT_SYSTEM, 0xcdef0123; since 1.1.76).   The  mes-
          sage  `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

          (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.

          (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.

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

          (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,

     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.


     On success, zero is returned.  On error, -1 is returned, and
     errno is set appropriately.


          Bad magic numbers or flag.

          A non-root user attempts to call reboot.


     reboot is Linux specific, and should not be used in programs
     intended to be portable.


     sync(2), bootparam(7), ctrlaltdel(8), halt(8), reboot(8)