6237ce0841
Add -N flag to reboot(8) which bypasses the userland sync(2) during reboot(8) while still allow the kernel sync during the reboot(2) syscall to occur. An example use of this is when rebooting with disconnected iSCSI sessions which would otherwise cause the reboot to hang on BIOs that will never complete. Reviewed by: bjk MFC after: 2 weeks Sponsored by: Multiplay Differential Revision: https://reviews.freebsd.org/D4449
168 lines
4.7 KiB
Groff
168 lines
4.7 KiB
Groff
.\" Copyright (c) 1990, 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.8 8.1 (Berkeley) 6/9/93
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.\" $FreeBSD$
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.\"
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.Dd Dec 12, 2015
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.Dt REBOOT 8
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.Os
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.Sh NAME
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.Nm reboot ,
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.Nm halt ,
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.Nm fastboot ,
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.Nm fasthalt
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.Nd stopping and restarting the system
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.Sh SYNOPSIS
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.Nm halt
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.Op Fl lNnpq
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.Op Fl k Ar kernel
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.Nm
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.Op Fl dlNnpqr
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.Op Fl k Ar kernel
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.Nm fasthalt
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.Op Fl lNnpq
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.Op Fl k Ar kernel
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.Nm fastboot
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.Op Fl dlNnpq
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.Op Fl k Ar kernel
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.Sh DESCRIPTION
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The
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.Nm halt
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and
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.Nm
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utilities flush the file system cache to disk, send all running processes
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a
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.Dv SIGTERM
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(and subsequently a
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.Dv SIGKILL )
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and, respectively, halt or restart the system.
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The action is logged, including entering a shutdown record into the user
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accounting database.
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.Pp
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The options are as follows:
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.Bl -tag -width indent
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.It Fl d
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The system is requested to create a crash dump.
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This option is
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supported only when rebooting, and it has no effect unless a dump
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device has previously been specified with
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.Xr dumpon 8 .
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.It Fl k Ar kernel
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Boot the specified
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.Ar kernel
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on the next system boot.
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If the kernel boots successfully, the
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.Em default
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kernel will be booted on successive boots, this is a one-shot option.
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If the boot fails, the system will continue attempting to boot
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.Ar kernel
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until the boot process is interrupted and a valid kernel booted.
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This may change in the future.
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.It Fl l
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The halt or reboot is
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.Em not
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logged to the system log.
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This option is intended for applications such as
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.Xr shutdown 8 ,
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that call
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.Nm
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or
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.Nm halt
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and log this themselves.
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.It Fl N
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The file system cache is not flushed during the initial process clean-up,
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however the kernel level
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.Xr reboot 2
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is still processed with a sync.
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This option can be useful for performing a
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.Dq best-effort
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reboot when devices might be unavailable.
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This can happen when devices have been disconnected, such as with
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.Xr iscsi 4 .
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.It Fl n
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The file system cache is not flushed.
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This option should probably not be used.
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.It Fl p
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The system will turn off the power if it can.
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If the power down action fails, the system
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will halt or reboot normally, depending on whether
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.Nm halt
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or
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.Nm
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was called.
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.It Fl q
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The system is halted or restarted quickly and ungracefully, and only
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the flushing of the file system cache is performed (if the
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.Fl n
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option is not specified).
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This option should probably not be used.
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.It Fl r
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The system kills all processes, unmounts all filesystems, mounts the new
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root filesystem, and begins the usual startup sequence.
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After changing vfs.root.mountfrom with
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.Xr kenv 8 ,
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.Nm Fl r
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can be used to change the root filesystem while preserving kernel state.
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.El
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.Pp
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The
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.Nm fasthalt
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and
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.Nm fastboot
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utilities are nothing more than aliases for the
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.Nm halt
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and
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.Nm
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utilities.
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.Pp
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Normally, the
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.Xr shutdown 8
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utility is used when the system needs to be halted or restarted, giving
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users advance warning of their impending doom and cleanly terminating
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specific programs.
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.Sh EXAMPLES
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Replace current root filesystem with UFS mounted from
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.Pa /dev/ada0s1a :
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.Bd -literal -offset indent
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kenv vfs.root.mountfrom=ufs:/dev/ada0s1a
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reboot -r
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.Ed
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.Sh SEE ALSO
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.Xr getutxent 3 ,
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.Xr boot 8 ,
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.Xr dumpon 8 ,
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.Xr nextboot 8 ,
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.Xr savecore 8 ,
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.Xr shutdown 8 ,
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.Xr sync 8
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.Sh HISTORY
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A
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.Nm
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utility appeared in
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.At v6 .
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