rsync - Feb 2025 - pre/post-xfer: How to distinguish between up- and download?

Hi all,

for an rsync-based incremental mechanism we use quite some pre- and
post-processing through pre-xfer and post-xfer. However it has turned
out, that the pre- and post-processing scripts must be able to differ
between uploads and downloads, as we require different processing steps
in either case. Is that possible at all? I can't find any rsync related
environment variables related to the transfer direction or any
mentioning of such a difference in the rsyncd.conf manpage.

/If/ the pre/post-xfer scripts cannot differentiate between up- and
downloads, then the only alternative that comes to my mind would be to
configure different modules for up- and download. Or would you see an
easier/alternative method to use different pre/post-xfer processings
depending on the rsync "direction"?

Cheers, Frank