169 lines
5.3 KiB
Groff
169 lines
5.3 KiB
Groff
.\" Copyright (c) 1980, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)reboot.2 8.1 (Berkeley) 6/4/93
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.\" $FreeBSD$
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.\"
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.Dd September 18, 2015
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.Dt REBOOT 2
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.Os
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.Sh NAME
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.Nm reboot
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.Nd reboot system or halt processor
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In unistd.h
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.In sys/reboot.h
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.Ft int
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.Fn reboot "int howto"
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.Sh DESCRIPTION
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The
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.Fn reboot
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system call
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reboots the system.
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Only the super-user may reboot a machine on demand.
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However, a reboot is invoked
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automatically in the event of unrecoverable system failures.
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.Pp
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The
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.Fa howto
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argument
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is a mask of options; the system call interface allows the following
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options, defined in the include file
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.In sys/reboot.h ,
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to be passed
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to the new kernel or the new bootstrap and init programs.
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.Bl -tag -width RB_INITNAMEA
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.It Dv RB_AUTOBOOT
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The default, causing the system to reboot in its usual fashion.
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.It Dv RB_ASKNAME
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Interpreted by the bootstrap program itself, causing it to
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prompt on the console as to what file should be booted.
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Normally, the system is booted from the file
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.Dq Ar xx Ns No (0,0)kernel ,
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where
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.Ar xx
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is the default disk name,
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without prompting for the file name.
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.It Dv RB_DFLTROOT
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Use the compiled in root device.
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Normally, the system uses the device from which it was booted
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as the root device if possible.
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(The default behavior is dependent on the ability of the bootstrap program
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to determine the drive from which it was loaded, which is not possible
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on all systems.)
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.It Dv RB_DUMP
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Dump kernel memory before rebooting; see
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.Xr savecore 8
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for more information.
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.It Dv RB_HALT
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The processor is simply halted; no reboot takes place.
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This option should be used with caution.
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.It Dv RB_POWEROFF
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After halting, the shutdown code will do what it can to turn
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off the power.
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This requires hardware support.
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.It Dv RB_INITNAME
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An option allowing the specification of an init program (see
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.Xr init 8 )
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other than
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.Pa /sbin/init
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to be run when the system reboots.
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This switch is not currently available.
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.It Dv RB_KDB
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Load the symbol table and enable a built-in debugger in the system.
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This option will have no useful function if the kernel is not configured
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for debugging.
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Several other options have different meaning if combined
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with this option, although their use may not be possible
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via the
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.Fn reboot
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system call.
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See
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.Xr ddb 4
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for more information.
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.It Dv RB_NOSYNC
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Normally, the disks are sync'd (see
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.Xr sync 8 )
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before the processor is halted or rebooted.
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This option may be useful if file system changes have been made manually
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or if the processor is on fire.
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.It Dv RB_REROOT
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Instead of rebooting, unmount all filesystems except the one containing
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currently-running executable, and mount root filesystem using the same
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mechanism which is used during normal boot, based on
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vfs.root.mountfrom
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.Xr kenv 1
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variable.
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.It Dv RB_RDONLY
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Initially mount the root file system read-only.
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This is currently the default, and this option has been deprecated.
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.It Dv RB_SINGLE
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Normally, the reboot procedure involves an automatic disk consistency
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check and then multi-user operations.
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.Dv RB_SINGLE
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prevents this, booting the system with a single-user shell
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on the console.
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.Dv RB_SINGLE
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is actually interpreted by the
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.Xr init 8
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program in the newly booted system.
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.El
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.Pp
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When no options are given (i.e.,
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.Dv RB_AUTOBOOT
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is used), the system is
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rebooted from file
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.Dq kernel
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in the root file system of unit 0
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of a disk chosen in a processor specific way.
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An automatic consistency check of the disks is normally performed
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(see
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.Xr fsck 8 ) .
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.Sh RETURN VALUES
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If successful, this call never returns.
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Otherwise, a -1 is returned and an error is returned in the global
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variable
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.Va errno .
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.Sh ERRORS
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.Bl -tag -width Er
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.It Bq Er EPERM
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The caller is not the super-user.
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.El
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.Sh SEE ALSO
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.Xr crash 8 ,
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.Xr halt 8 ,
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.Xr init 8 ,
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.Xr reboot 8 ,
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.Xr savecore 8
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.Sh HISTORY
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The
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.Fn reboot
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system call appeared in
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.Bx 4.0 .
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