sd_watchdog_enabled — Check whether the service manager expects watchdog keep-alive notifications from a service
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.
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
with a message string of
parameter is non-zero,
sd_watchdog_enabled() will unset
$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.
usec parameter is
will write the timeout in µs for the watchdog
logic to it.
To enable service supervision with the watchdog
WatchdogSec= in service
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
These APIs are implemented as a shared
library, which can be compiled and linked to with the
Internally, this functions parses the
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.
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.
The watchdog functionality and the
$WATCHDOG_USEC variable were
added in systemd-41.
function was added in systemd-209. Since that version
$WATCHDOG_PID variable is also