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.TH WD_KEEPALIVE 8 "June 2015"
.UC 4
.SH NAME
wd_keepalive \- a simplified software watchdog daemon
.SH SYNOPSIS
.B wd_keepalive
.RB [ \-c " \fIfilename\fR|" \-\-config\-file " \fIfilename\fR]"
.SH DESCRIPTION
This is a simplified version of the
.B watchdog
daemon. Unlike the full watchdog, this daemon run no tests and only serves to keep
the hardware timer refreshed. Typically this is used on system start-up to
provide protection before the services that the full version tests are running,
and on shutdown to continue the refresh while those services are stopped.
.PP
If configured so it only opens
.IR /dev/watchdog ,
and keeps writing to it often enough to keep the kernel from resetting,
at least once per minute. Each write delays the reboot
time another minute. After a minute of inactivity the watchdog hardware will
cause a reset. In the case of the software watchdog the ability to
reboot will depend on the state of the machines and interrupts.
.PP
The wd_keepalive daemon can be stopped without causing a reboot if the device
.I /dev/watchdog
is closed correctly, unless your kernel is compiled with the
.I CONFIG_WATCHDOG_NOWAYOUT
option enabled.
.PP
Under high system load
.B wd_keepalive
might be swapped out of memory and may fail
to make it back in in time. Under these circumstances the Linux kernel will
reset the machine. To make sure you won't get unnecessary reboots make
sure you have the variable
.I realtime
set to
.I yes
in the configuration file
.IR watchdog.conf .
This adds real time support to
.BR wd_keepalive :
it will lock itself into memory and there should be no problem even under the
highest of loads.
.PP
On system running out of memory the kernel will try to free enough memory by killing process. The
.B wd_keepalive
daemon itself is exempted from this so-called out-of-memory killer.
.SH OPTIONS
Available command line options are the following:
.TP
.BR \-c " \fIconfig-file\fR, " \-\-config\-file " \fIconfig-file"
Use
.I config-file
as the configuration file instead of the default
.IR /etc/watchdog.conf .
.TP
.BR \-X " \fInum\fR, " \-\-loop\-exit " \fInum"
Run for 'num' loops then exit as if SIG_TERM was received. Intended for test/debug (e.g. using
.B valgrind
for checking memory access). If the daemon exits on a loop counter and you have the
.I CONFIG_WATCHDOG_NOWAYOUT
option compiled for the kernel or device-driver then an unplanned reboot will follow - be warned!
.SH FILES
.TP
.I /dev/watchdog
The watchdog device.
.TP
.I /var/run/wd_keepalive.pid
The pid file of the running
.BR wd_keepalive .
.SH "SEE ALSO"
.BR watchdog.conf (5)
.TP
.BR watchdog (8)
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