WATCHDOGD(8) FreeBSD System Manager's Manual WATCHDOGD(8)
NAME
watchdogd - watchdog daemon
SYNOPSIS
watchdogd [-dnSw] [--debug] [--softtimeout] [--softtimeout-action action]
[--pretimeout timeout] [--pretimeout-action action] [-e cmd]
[-I file] [-s sleep] [-t timeout] [-T script_timeout]
[-x exit_timeout]
DESCRIPTION
The watchdogd utility interfaces with the kernel's watchdog facility to
ensure that the system is in a working state. If watchdogd is unable to
interface with the kernel over a specific timeout, the kernel will take
actions to assist in debugging or restarting the computer.
If -e cmd is specified, watchdogd will attempt to execute this command
with system(3), and only if the command returns with a zero exit code
will the watchdog be reset. If -e cmd is not specified, the daemon will
perform a trivial file system check instead.
The -n argument 'dry-run' will cause watchdog not to arm the system
watchdog and instead only run the watchdog function and report on
failures. This is useful for developing new watchdogd scripts as the
system will not reboot if there are problems with the script.
The -s sleep argument can be used to control the sleep period between
each execution of the check and defaults to 10 seconds.
The -t timeout specifies the desired timeout period in seconds. The
default timeout is 128 seconds.
One possible circumstance which will cause a watchdog timeout is an
interrupt storm. If this occurs, watchdogd will no longer execute and
thus the kernel's watchdog routines will take action after a configurable
timeout.
The -T script_timeout specifies the threshold (in seconds) at which the
watchdogd will complain that its script has run for too long. If unset
script_timeout defaults to the value specified by the -s sleep option.
The -x exit_timeout argument is the timeout period (in seconds) to leave
in effect when the program exits. Using -x with a non-zero value
protects against lockup during a reboot by triggering a hardware reset if
the software reboot doesn't complete before the given timeout expires.
Upon receiving the SIGTERM or SIGINT signals, watchdogd will terminate,
after first instructing the kernel to either disable the timeout or reset
it to the value given by -x exit_timeout.
The watchdogd utility recognizes the following runtime options:
-I file Write the process ID of the watchdogd
utility in the specified file.
-d --debug Do not fork. When this option is
specified, watchdogd will not fork into
the background at startup.
-S Do not send a message to the system
logger when the watchdog command takes
longer than expected to execute. The
default behaviour is to log a warning via
the system logger with the LOG_DAEMON
facility, and to output a warning to
standard error.
-w Complain when the watchdog script takes
too long. This flag will cause watchdogd
to complain when the amount of time to
execute the watchdog script exceeds the
threshold of 'sleep' option.
--pretimeout timeout Set a "pretimeout" watchdog. At
"timeout" seconds before the watchdog
will fire attempt an action. The action
is set by the --pretimeout-action flag.
The default is just to log a message
(WD_SOFT_LOG) via log(9).
--pretimeout-action action Set the timeout action for the
pretimeout. See the section Timeout
Actions.
--softtimeout Instead of arming the various hardware
watchdogs, only use a basic software
watchdog. The default action is just to
log(9) a message (WD_SOFT_LOG).
--softtimeout-action action Set the timeout action for the
softtimeout. See the section Timeout
Actions.
Timeout Actions
The following timeout actions are available via the --pretimeout-action
and --softtimeout-action flags:
panic Call panic(9) when the timeout is reached.
ddb Enter the kernel debugger via kdb_enter(9) when the timeout
is reached.
log Log a message using log(9) when the timeout is reached.
printf call the kernel printf(9) to display a message to the
console and dmesg(8) buffer.
Actions can be combined in a comma separated list as so: log,printf which
would both printf(9) and log(9) which will send messages both to dmesg(8)
and the kernel log(4) device for syslogd(8).
FILES
/var/run/watchdogd.pid
EXAMPLES
Debugging watchdogd and/or your watchdog script.
This is a useful recipe for debugging watchdogd and your watchdog script.
(Note that ^C works oddly because watchdogd calls system(3) so the first
^C will terminate the "sleep" command.)
Explanation of options used:
1. Set Debug on (--debug)
2. Set the watchdog to trip at 30 seconds. (-t 30)
3. Use of a softtimeout:
1. Use a softtimeout (do not arm the hardware
watchdog). (--softtimeout)
2. Set the softtimeout action to do both kernel
printf(9) and log(9) when it trips.
(--softtimeout-action log,printf)
4. Use of a pre-timeout:
1. Set a pre-timeout of 15 seconds (this will later
trigger a panic/dump). (--pretimeout 15)
2. Set the action to also kernel printf(9) and log(9)
when it trips. (--pretimeout-action log,printf)
5. Use of a script:
1. Run "sleep 60" as a shell command that acts as the
watchdog (-e 'sleep 60')
2. Warn us when the script takes longer than 1 second
to run (-w)
watchdogd --debug -t 30 \
--softtimeout --softtimeout-action log,printf \
--pretimeout 15 --pretimeout-action log,printf \
-e 'sleep 60' -w
Production use of example
1. Set hard timeout to 120 seconds (-t 120)
2. Set a panic to happen at 60 seconds (to trigger a crash(8) for
dump analysis):
1. Use of pre-timeout (--pretimeout 60)
2. Specify pre-timeout action (--pretimeout-action
log,printf,panic )
3. Use of a script:
1. Run your script (-e '/path/to/your/script 60')
2. Log if your script takes a longer than 15 seconds
to run time. (-w -T 15)
watchdogd -t 120 \
--pretimeout 60 --pretimeout-action log,printf,panic \
-e '/path/to/your/script 60' -w -T 15
SEE ALSO
watchdog(4), watchdog(8), watchdog(9)
HISTORY
The watchdogd utility appeared in FreeBSD 5.1.
AUTHORS
The watchdogd utility and manual page were written by Sean Kelly
<smkelly@FreeBSD.org> and Poul-Henning Kamp <phk@FreeBSD.org>.
Some contributions made by Jeff Roberson <jeff@FreeBSD.org>.
The pretimeout and softtimeout action system was added by Alfred
Perlstein <alfred@freebsd.org>.
FreeBSD 13.1-RELEASE-p6 May 11, 2015 FreeBSD 13.1-RELEASE-p6
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