My apologies if this has been answered already, I did search but did not find an answer.

Is there a way to write tags back to images or sidecar files? (EXIF, IPTC or any standard sidecar)

Or at minimal, is there a way to export tags from the DB (filename + tags) so I can script exiftool later to bring the tags back to image files?

Thank you.

There is not. That would require a lot IPTC support library with update capability. There may be such, but we have not look.

Thank you.

Exiftool is the best for manipulating image's metadata and it's a perl library http://www.sno.phy.queensu.ca/~phil/exiftool/ ...maybe that could be used.

Back to my 2nd question. Could one relatively easy export from the SQL DB the tag info with file-names for later script processing?

1. Generally Zenphoto is a PHP application so I would say that (besides us using Javascript as well) we probably should stick with that. Besides that I have no knowledge about perl or if it is generally available on servers nowadays. But you free to provide a 3rd party plugin yourself if you need it. See here please: http://www.zenphoto.org/news/general-contributor-guidelines

2. You can export database tables via tools like phpmyadmin. But of course you would have to code something to process the data and its connections between tags and images tables.