When I run the command “duplicacy prune -log -keep … -all” it creates a file named “prune-log-yymmdd-hhmmss” in the repository’s .duplicacy/logs directory, as well as producing the expected log information on stdout. Comparing this behaviour with (for example) the behaviour of the backup command, it seems to me that this log file should not be created.
So far I have only seen this spurious log file have zero size, but that may be because the corresponding prune operations have not yet deleted any snapshots.
I wonder whether this is a bug or something more subtle that I don’t understand…
(This is with duplicacy 2.1.1 on macOS 10.12.)