WD_KEEPALIVE(8)

💖 WD_KEEPALIVE(8) 💖

okay bestie, welcome to the System Manager's Manual section, page wd_keepalive(8) 🎀 this is the whole vibe, let's get into it ✨

🦋 NAME 🦋

wd_keepalive — a simplified software watchdog daemon 🐶

🌸 SYNOPSIS 🌸

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

✨ DESCRIPTION ✨

So here's the tea ☕: this is a simplified version of the watchdog daemon. Unlike the full watchdog, this one runs no tests at all — it literally just exists to keep the hardware timer refreshed. That's it. That's the whole job. 👑

Typically you'd use it:

• at system start-up, to give protection before the services that the full version tests are actually running, and
• at shutdown, to keep the refresh going while those services are stopped.

If it's configured that way, it only opens /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. ⏰ And in the case of the software watchdog, the ability to reboot will depend on the state of the machines and interrupts. (iykyk 🙈)

The wd_keepalive daemon can be stopped without causing a reboot if the device /dev/watchdog is closed correctly — unless your kernel is compiled with the CONFIG_WATCHDOG_NOWAYOUT option enabled. 💀

Under high system load, wd_keepalive might get swapped out of memory and may fail to make it back in time. Under those circumstances the Linux kernel will reset the machine. 😭

To make sure you don't get unnecessary reboots, make sure you have the variable realtime set to yes in the configuration file watchdog.conf. That adds real time support to wd_keepalive: it will lock itself into memory, and there should be no problem even under the highest of loads. 🫶

On a system running out of memory, the kernel will try to free enough memory by killing processes. The wd_keepalive daemon itself is exempted from this so-called out-of-memory killer. not me being the main character of memory management 💅

💅 OPTIONS 💅

Available command line options are the following, bestie:

• -c config-file, --config-file config-file — use config-file as the configuration file instead of the default /etc/watchdog.conf. 🎀
• -X num, --loop-exit num — run for num loops then exit as if SIG_TERM was received. Intended for test/debug (e.g. using valgrind for checking memory access).

⚠️ If the daemon exits on a loop counter and you have the CONFIG_WATCHDOG_NOWAYOUT option compiled for the kernel or device-driver, then an unplanned reboot will follow — be warned! 🚨 no cap, this one is for real.

🌈 FILES 🌈

• /dev/watchdog — the watchdog device. 🐕
• /var/run/wd_keepalive.pid — the pid file of the running wd_keepalive. 📌

👑 SEE ALSO 👑

• watchdog.conf(5)
• watchdog(8)

and that's the whole page, periodt 💜 go forth and keep those timers refreshed, bestie, you got this 🌟

sending you off with love from the 4th Berkeley Distribution, version dated June 2015 — mwah 🎀💖 bye bestie!! ✨