Exit code to indicate sync changes

[Yuri D'E. <wa...@th...>]

Is there a way to make mbsync differentiate between successful sync
with and without changes?

I'd love to have diff(1) style exit codes: 0: success (with changes), 1:
(errors), 2: success (no changes).

I remember I was asking for bitfield style error codes to handle
timeouts and retries better, but right now I'd be more pressed to speed
up mail fetching by not re-indexing the maildir content if no change
occurred during sync.

I'd be prepared to modify mbsync myself if there is consensus on the
behavior. To keep changes to a minimum, we could add a new flag to
request the exit code of 2 when some syncing occurred. It could make
sense to differentiate between master/slave changes, but to be honest
having just a simple change flag would be more than enough for me.

It seems you could just collect the status counters and just emit an
exit status of 2 if any of them are non-zero.