1WD_KEEPALIVE(8)             System Manager's Manual            WD_KEEPALIVE(8)
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NAME

6       wd_keepalive - a simplified software watchdog daemon
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SYNOPSIS

9       wd_keepalive [-c filename|--config-file filename]
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DESCRIPTION

12       This  is  a  simplified version of the watchdog daemon. Unlike the full
13       watchdog, this daemon run no tests and only serves to keep the hardware
14       timer  refreshed.  Typically this is used on system start-up to provide
15       protection before the services that the full version tests are running,
16       and  on  shutdown  to  continue  the  refresh  while those services are
17       stopped.
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19       If configured so it only opens /dev/watchdog, and keeps writing  to  it
20       often  enough  to  keep  the  kernel  from resetting, at least once per
21       minute. Each write delays the  reboot  time  another  minute.  After  a
22       minute  of  inactivity the watchdog hardware will cause a reset. In the
23       case of the software watchdog the ability to reboot will depend on  the
24       state of the machines and interrupts.
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26       The  wd_keepalive daemon can be stopped without causing a reboot if the
27       device /dev/watchdog is closed correctly, unless your  kernel  is  com‐
28       piled with the CONFIG_WATCHDOG_NOWAYOUT option enabled.
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30       Under  high system load wd_keepalive might be swapped out of memory and
31       may fail to make it back in in  time.  Under  these  circumstances  the
32       Linux  kernel will reset the machine. To make sure you won't get unnec‐
33       essary reboots make sure you have the variable realtime set to  yes  in
34       the  configuration  file watchdog.conf.  This adds real time support to
35       wd_keepalive: it will lock itself into memory and there should   be  no
36       problem even under the highest of loads.
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38       On system running out of memory the kernel will try to free enough mem‐
39       ory by killing process. The wd_keepalive daemon itself is exempted from
40       this so-called out-of-memory killer.
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OPTIONS

43       Available command line options are the following:
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45       -c config-file, --config-file config-file
46              Use config-file as the configuration file instead of the default
47              /etc/watchdog.conf.
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49       -X num, --loop-exit num
50              Run for 'num' loops then  exit  as  if  SIG_TERM  was  received.
51              Intended for test/debug (e.g. using valgrind for checking memory
52              access). If the daemon exits on a loop counter and you have  the
53              CONFIG_WATCHDOG_NOWAYOUT  option  compiled  for  the  kernel  or
54              device-driver then an unplanned reboot will follow - be warned!
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FILES

57       /dev/watchdog
58              The watchdog device.
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60       /var/run/wd_keepalive.pid
61              The pid file of the running wd_keepalive.
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SEE ALSO

64       watchdog.conf(5)
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66       watchdog(8)
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704th Berkeley Distribution          June 2015                   WD_KEEPALIVE(8)
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