systemd Developer Lennart Poettering lennart@poettering.net sd_watchdog_enabled 3 sd_watchdog_enabled Check whether the service manager expects watchdog keep-alive notifications from a service #include <systemd/sd-daemon.h> int sd_watchdog_enabled int unset_environment uint64_t *usec sd_watchdog_enabled() may be called by a service to detect whether the service manager expects regular keep-alive watchdog notification events from it, and the timeout after which the manager will act on the service if it did not get such a notification. If the $WATCHDOG_USEC environment variable is set, and the $WATCHDOG_PID variable is unset or set to the PID of the current process, the service manager expects notifications from this process. The manager will usually terminate a service when it does not get a notification message within the specified time after startup and after each previous message. It is recommended that a daemon sends a keep-alive notification message to the service manager every half of the time returned here. Notification messages may be sent with sd_notify3 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.service5 for details. Use sd_event_set_watchdog3 to enable automatic watchdog support in sd-event3-based event loops. On failure, this call returns a negative errno-style error code. If the service manager expects watchdog keep-alive notification messages to be sent, > 0 is returned, otherwise 0 is returned. Only if the return value is > 0, the usec parameter is valid after the call. 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. $WATCHDOG_PID 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. systemd1, sd-daemon3, daemon7, systemd.service5, sd_notify3, sd_event_set_watchdog3