326 lines
8.4 KiB
Groff
326 lines
8.4 KiB
Groff
.\" Copyright (c) 2013 iXsystems.com,
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.\" author: Alfred Perlstein <alfred@freebsd.org>
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.\" Copyright (c) 2004 Poul-Henning Kamp <phk@FreeBSD.org>
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.\" Copyright (c) 2003 Sean M. Kelly <smkelly@FreeBSD.org>
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.\" 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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.\"
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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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.\" $FreeBSD$
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.\"
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.Dd May 11, 2015
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.Dt WATCHDOGD 8
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.Os
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.Sh NAME
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.Nm watchdogd
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.Nd watchdog daemon
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.Sh SYNOPSIS
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.Nm
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.Op Fl dnSw
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.Op Fl -debug
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.Op Fl -softtimeout
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.Op Fl -softtimeout-action Ar action
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.Op Fl -pretimeout Ar timeout
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.Op Fl -pretimeout-action Ar action
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.Op Fl e Ar cmd
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.Op Fl I Ar file
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.Op Fl s Ar sleep
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.Op Fl t Ar timeout
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.Op Fl T Ar script_timeout
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.Op Fl x Ar exit_timeout
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.Sh DESCRIPTION
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The
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.Nm
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utility interfaces with the kernel's watchdog facility to ensure
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that the system is in a working state.
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If
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.Nm
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is unable to interface with the kernel over a specific timeout,
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the kernel will take actions to assist in debugging or restarting the computer.
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.Pp
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If
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.Fl e Ar cmd
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is specified,
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.Nm
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will attempt to execute this command with
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.Xr system 3 ,
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and only if the command returns with a zero exit code will the
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watchdog be reset.
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If
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.Fl e Ar cmd
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is not specified, the daemon will perform a trivial file system
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check instead.
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.Pp
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The
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.Fl n
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argument 'dry-run' will cause watchdog not to arm the system watchdog and
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instead only run the watchdog function and report on failures.
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This is useful for developing new watchdogd scripts as the system will not
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reboot if there are problems with the script.
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.Pp
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The
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.Fl s Ar sleep
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argument can be used to control the sleep period between each execution
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of the check and defaults to 10 seconds.
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.Pp
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The
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.Fl t Ar timeout
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specifies the desired timeout period in seconds.
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The default timeout is 128 seconds.
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.Pp
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One possible circumstance which will cause a watchdog timeout is an interrupt
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storm.
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If this occurs,
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.Nm
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will no longer execute and thus the kernel's watchdog routines will take
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action after a configurable timeout.
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.Pp
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The
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.Fl T Ar script_timeout
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specifies the threshold (in seconds) at which the watchdogd will complain
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that its script has run for too long.
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If unset
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.Ar script_timeout
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defaults to the value specified by the
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.Fl s Ar sleep
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option.
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.Pp
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The
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.Fl x Ar exit_timeout
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argument is the timeout period (in seconds) to leave in effect when the
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program exits.
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Using
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.Fl x
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with a non-zero value protects against lockup during a reboot by
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triggering a hardware reset if the software reboot doesn't complete
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before the given timeout expires.
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.Pp
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Upon receiving the
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.Dv SIGTERM
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or
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.Dv SIGINT
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signals,
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.Nm
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will terminate, after first instructing the kernel to either disable the
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timeout or reset it to the value given by
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.Fl x Ar exit_timeout .
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.Pp
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The
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.Nm
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utility recognizes the following runtime options:
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.Bl -tag -width 30m
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.It Fl I Ar file
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Write the process ID of the
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.Nm
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utility in the specified file.
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.It Fl d Fl -debug
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Do not fork.
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When this option is specified,
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.Nm
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will not fork into the background at startup.
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.It Fl S
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Do not send a message to the system logger when the watchdog command takes
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longer than expected to execute.
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The default behaviour is to log a warning via the system logger with the
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LOG_DAEMON facility, and to output a warning to standard error.
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.It Fl w
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Complain when the watchdog script takes too long.
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This flag will cause watchdogd to complain when the amount of time to
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execute the watchdog script exceeds the threshold of 'sleep' option.
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.It Fl -pretimeout Ar timeout
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Set a "pretimeout" watchdog.
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At "timeout" seconds before the watchdog will fire attempt an action.
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The action is set by the --pretimeout-action flag.
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The default is just to log a message (WD_SOFT_LOG) via
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.Xr log 9 .
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.It Fl -pretimeout-action Ar action
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Set the timeout action for the pretimeout.
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See the section
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.Sx Timeout Actions .
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.It Fl -softtimeout
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Instead of arming the various hardware watchdogs, only use a basic software
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watchdog.
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The default action is just to
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.Xr log 9
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a message (WD_SOFT_LOG).
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.It Fl -softtimeout-action Ar action
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Set the timeout action for the softtimeout.
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See the section
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.Sx Timeout Actions .
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.El
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.Sh Timeout Actions
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The following timeout actions are available via the
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.Fl -pretimeout-action
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and
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.Fl -softtimeout-action
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flags:
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.Bl -tag -width ".Ar printf "
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.It Ar panic
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Call
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.Xr panic 9
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when the timeout is reached.
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.It Ar ddb
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Enter the kernel debugger via
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.Xr kdb_enter 9
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when the timeout is reached.
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.It Ar log
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Log a message using
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.Xr log 9
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when the timeout is reached.
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.It Ar printf
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call the kernel
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.Xr printf 9
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to display a message to the console and
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.Xr dmesg 8
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buffer.
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.El
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.Pp
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Actions can be combined in a comma separated list as so:
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.Ar log,printf
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which would both
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.Xr printf 9
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and
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.Xr log 9
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which will send messages both to
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.Xr dmesg 8
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and the kernel
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.Xr log 4
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device for
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.Xr syslogd 8 .
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.Sh FILES
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.Bl -tag -width ".Pa /var/run/watchdogd.pid" -compact
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.It Pa /var/run/watchdogd.pid
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.El
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.Sh EXAMPLES
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.Ss Debugging watchdogd and/or your watchdog script.
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This is a useful recipe for debugging
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.Nm
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and your watchdog script.
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.Pp
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(Note that ^C works oddly because
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.Nm
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calls
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.Xr system 3
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so the
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first ^C will terminate the "sleep" command.)
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.Pp
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Explanation of options used:
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.Bl -enum -offset indent -compact
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.It
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Set Debug on (--debug)
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.It
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Set the watchdog to trip at 30 seconds. (-t 30)
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.It
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Use of a softtimeout:
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.Bl -enum -offset indent -compact -nested
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.It
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Use a softtimeout (do not arm the hardware watchdog).
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(--softtimeout)
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.It
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Set the softtimeout action to do both kernel
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.Xr printf 9
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and
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.Xr log 9
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when it trips.
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(--softtimeout-action log,printf)
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.El
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.It
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Use of a pre-timeout:
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.Bl -enum -offset indent -compact -nested
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.It
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Set a pre-timeout of 15 seconds (this will later trigger a panic/dump).
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(--pretimeout 15)
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.It
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Set the action to also kernel
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.Xr printf 9
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and
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.Xr log 9
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when it trips.
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(--pretimeout-action log,printf)
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.El
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.It
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Use of a script:
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.Bl -enum -offset indent -compact -nested
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.It
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Run "sleep 60" as a shell command that acts as the watchdog (-e 'sleep 60')
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.It
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Warn us when the script takes longer than 1 second to run (-w)
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.El
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.El
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.Bd -literal
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watchdogd --debug -t 30 \\
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--softtimeout --softtimeout-action log,printf \\
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--pretimeout 15 --pretimeout-action log,printf \\
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-e 'sleep 60' -w
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.Ed
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.Ss Production use of example
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.Bl -enum -offset indent -compact
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.It
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Set hard timeout to 120 seconds (-t 120)
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.It
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Set a panic to happen at 60 seconds (to trigger a
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.Xr crash 8
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for dump analysis):
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.Bl -enum -offset indent -compact -nested
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.It
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Use of pre-timeout (--pretimeout 60)
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.It
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Specify pre-timeout action (--pretimeout-action log,printf,panic )
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.El
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.It
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Use of a script:
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.Bl -enum -offset indent -compact -nested
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.It
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Run your script (-e '/path/to/your/script 60')
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.It
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Log if your script takes a longer than 15 seconds to run time. (-w -T 15)
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.El
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.El
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.Bd -literal
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watchdogd -t 120 \\
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--pretimeout 60 --pretimeout-action log,printf,panic \\
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-e '/path/to/your/script 60' -w -T 15
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.Ed
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.Sh SEE ALSO
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.Xr watchdog 4 ,
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.Xr watchdog 8 ,
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.Xr watchdog 9
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.Sh HISTORY
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The
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.Nm
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utility appeared in
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.Fx 5.1 .
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.Sh AUTHORS
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.An -nosplit
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The
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.Nm
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utility and manual page were written by
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.An Sean Kelly Aq Mt smkelly@FreeBSD.org
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and
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.An Poul-Henning Kamp Aq Mt phk@FreeBSD.org .
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.Pp
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Some contributions made by
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.An Jeff Roberson Aq Mt jeff@FreeBSD.org .
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.Pp
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The pretimeout and softtimeout action system was added by
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.An Alfred Perlstein Aq Mt alfred@freebsd.org .
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