reboot - reboot system or halt processor
reboot() reboots the system. Only the superuser may reboot
a machine on
demand. However, a reboot is invoked automatically in the
event of unrecoverable
howto is a mask of options; the system call interface allows
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
RB_ASKNAME Interpreted by the bootstrap program itself,
causing it to
prompt on the console as to what file should
Normally, the system is booted from the file
``xx(0,0)bsd'', where xx is the default disk
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
which it was loaded, which is not possible on
RB_DUMP Dump kernel memory before rebooting; see
RB_HALT The processor is simply halted; no reboot
RB_POWERDOWN If used in conjunction with RB_HALT, and if
hardware supports the function, the system
will be powered
RB_USERREQ By default, the system will halt if reboot()
is called during
startup (before the system has finished
even if RB_HALT is not specified. This
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,
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
(see init(8)) other than /sbin/init to be run
when the system
reboots. This switch is not currently
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
although their use may not be possible via the
call. See ddb(4) for more information.
RB_NOSYNC Normally, the disks are sync'd (see sync(8))
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
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
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
An automatic consistency check of the disks is
performed (see fsck(8)).
If successful, this call never returns. Otherwise, a -1 is
an error is returned in the global variable errno.
[EPERM] The caller is not the superuser.
ddb(4), crash(8), halt(8), init(8), reboot(8), savecore(8),
The reboot() function call appeared in 4.0BSD.
Not all platforms support all possible arguments. For example,
RB_POWERDOWN is supported only on the i386, sparc, and
OpenBSD 3.6 June 4, 1993
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