[Nut-upsdev] standardizing debug log levels [was: passing nut_debug_level from upsdrvctl to drivers]

[Arjen de Korte]

[...]

> Another possibility is to tag the debug output in such a way that we
> can use tools like grep or awk to filter debug messages. Example
> output from libhid (Martin Krafft wrote this part):
>
>   TRACE: hid_init(): initialising USB subsystem...
>   TRACE: hid_init(): scanning for USB busses...
>   TRACE: hid_init(): scanning for USB devices...
>  NOTICE: hid_init(): successfully initialised HID library.
>
> The "trace" messages are one level lower than "notice", and are
> controlled by a variable similar to nut_debug_level. If we wanted to,
> we could print the debug level itself, and filter based on that after
> the fact.

As an interim solution, this would be a good solution. This would require
far less effort, since most of the changes would be in the upsdebug*
functions. Probably the only thing that would need changes if we would go
ahead with this, would be the script to generate a subdriver for
usbhid-ups.

> Maybe the -D flags could control what gets printed to the console, and
> if any -D flags are used, a debug log gets written. (We could
> standardize the filename to include the driver name and date/time, as
> well.)

This will be a little more difficult to implement. Probably the only place
where we are 'guaranteed' to have write access (if everything is
configured properly, that is) is the STATEPATH and I'm not sure that it
will be easy to tell people where the file can be found. In any case, we
should probably use a fixed name and overwrite any existing logs, so that
we don't have to deal with versioning either. This in order not to confuse
people which one to use and to prevent flooding the filesystem if they
forget to delete older versions.

Best regards, Arjen