devmon needs better output format

[lukehutch]

devmon output is hard to parse in a future-proof way, because there is no record end marker, so a parser has to be stateful, and keep parsing drive metadata fields until it has all the fields it is expecting (then it can ignore everything else). Finding the last field the parser expects has to be used for the record end marker. But if field names change, this means that a devmon parser can break too.

Can you please support some other output format, enabled with a switch, e.g. JSON or XML, so that every change event can be parsed computationally in a more robust way? You can output one change event per line, and each line should be a complete JSON or XML document describing the change, and all the drive metadata after the change.

Thanks!