NAME    [Toc]    [Back]

     reboot - reboot system or halt processor

SYNOPSIS    [Toc]    [Back]

     #include <unistd.h>
     #include <sys/reboot.h>

     int
     reboot(int howto);

DESCRIPTION    [Toc]    [Back]

     reboot() reboots the system.  Only the superuser may  reboot
a machine on
     demand.   However,  a reboot is invoked automatically in the
event of unrecoverable
 system failures.

     howto is a mask of options; the system call interface allows
the following
  options, defined in the include file <sys/reboot.h>, to
be passed to
     the new kernel or the new bootstrap and init programs.

     RB_AUTOBOOT   The default, causing the system to  reboot  in
its usual
                   fashion.

     RB_ASKNAME     Interpreted  by the bootstrap program itself,
causing it to
                   prompt on the console as to what  file  should
be booted.
                   Normally, the system is booted from the file
                   ``xx(0,0)bsd'',  where  xx is the default disk
name, without
                   prompting for the file name.

     RB_DFLTROOT   Use the compiled in  root  device.   Normally,
the system uses
                   the  device  from  which  it was booted as the
root device if
                   possible.  (The default behavior is  dependent
on the ability
  of  the bootstrap program to determine the
drive from
                   which it was loaded, which is not possible  on
all systems.)

     RB_DUMP        Dump  kernel  memory  before  rebooting;  see
savecore(8) for
                   more information.

     RB_HALT       The processor  is  simply  halted;  no  reboot
takes place.

     RB_POWERDOWN   If  used  in conjunction with RB_HALT, and if
the system
                   hardware supports  the  function,  the  system
will be powered
                   off.

     RB_USERREQ     By  default, the system will halt if reboot()
is called during
 startup (before the  system  has  finished
autoconfiguration),
 even if RB_HALT is not specified.  This
is because
                   panic(9)s during startup  will  probably  just
repeat on the
                   next  boot.   Use  of this option implies that
the user has
                   requested the action specified  (for  example,
using the
                   ddb(4)  boot  reboot  command),  so the system
will reboot if a
                   halt is not explicitly requested.

     RB_INITNAME   An option allowing  the  specification  of  an
init program
                   (see  init(8)) other than /sbin/init to be run
when the system
 reboots.  This  switch  is  not  currently
available.

     RB_KDB         Load  the  symbol table and enable a built-in
debugger in the
                   system.  This option will have no useful function if the
                   kernel  is not configured for debugging.  Several other options
 have different meaning if combined  with
this option,
                   although their use may not be possible via the
reboot()
                   call.  See ddb(4) for more information.

     RB_NOSYNC     Normally, the disks are sync'd  (see  sync(8))
before the
                   processor  is halted or rebooted.  This option
may be useful
                   if file system changes have been made manually
or if the
                   processor is on fire.

     RB_RDONLY      Initially mount the root file system read-only.  This is
                   currently the default,  and  this  option  has
been deprecated.

     RB_SINGLE     Normally, the reboot procedure involves an automatic disk
                   consistency check and then  multi-user  operations.
                   RB_SINGLE  prevents  this,  booting the system
with a singleuser
 shell on the console.  RB_SINGLE is actually interpreted
  by  the  init(8)  program in the newly
booted system.

                   When no options are given  (i.e.,  RB_AUTOBOOT
is used), the
                   system  is  rebooted  from file ``bsd'' in the
root file system
 of unit 0 of a disk chosen in a  processor
specific way.
                   An automatic consistency check of the disks is
normally
                   performed (see fsck(8)).

RETURN VALUES    [Toc]    [Back]

     If successful, this call never returns.  Otherwise, a -1  is
returned and
     an error is returned in the global variable errno.

ERRORS    [Toc]    [Back]

     [EPERM]       The caller is not the superuser.

SEE ALSO    [Toc]    [Back]

     ddb(4),  crash(8), halt(8), init(8), reboot(8), savecore(8),
boot(9),
     panic(9)

HISTORY    [Toc]    [Back]

     The reboot() function call appeared in 4.0BSD.

BUGS    [Toc]    [Back]

     Not all platforms support all possible arguments.  For example,
     RB_POWERDOWN  is  supported  only  on  the  i386, sparc, and
mac68k platforms.

OpenBSD      3.6                           June      4,      1993