int sd_watchdog_enabled(int unset_environment, uint64_t *usec);sd_notify(3) with a message string of "WATCHDOG=1". If the unset_environment parameter is non-zero, sd_watchdog_enabled() will unset the $WATCHDOG_USEC and $WATCHDOG_PID environment variables before returning (regardless of whether the function call itself succeeded or not). Those variables are no longer inherited by child processes. Further calls to sd_watchdog_enabled() will also return with zero. If the usec parameter is non-NULL, sd_watchdog_enabled() will write the timeout in µs for the watchdog logic to it. To enable service supervision with the watchdog logic, use WatchdogSec= in service files. See systemd.service(5) for details. Use sd_event_set_watchdog(3) to enable automatic watchdog support in sd-event(3)-based event loops. pkg-config(1) file. Internally, this function parses the $WATCHDOG_PID and $WATCHDOG_USEC environment variable. The call will ignore these variables if $WATCHDOG_PID does not contain the PID of the current process, under the assumption that in that case, the variables were set for a different process further up the process tree.
Set by the system manager for supervised process for which watchdog support is enabled, and contains the PID of that process. See above for details.$WATCHDOG_USEC
Set by the system manager for supervised process for which watchdog support is enabled, and contains the watchdog timeout in µs. See above for details.systemd(1), sd-daemon(3), daemon(7), systemd.service(5), sd_notify(3), sd_event_set_watchdog(3)