I am dumb exiftool newbie, and not much of Linex guy either. But I thought given your example even I could do this. I have a bunch of jpg files that have geotagging added (IPTC: city, state/province and country, plus GPS:latitude and longitude), and I have identically named CR2 files that I want to geotag. Based on your example in the copy metadata thread (exiftool -tagsfromfile SRCDIR/%f.tif DSTDIR -ext jpg), I put the jpg and cr2 files in a directory test and did:
exiftool -tagsfromfile test/%f.jpg test -ext cr2
That indeed created new cr2 files but it does not appear that the new cr2 files have any different tags from the old ones; at least, the IPTC and GPS tags have not been modified/added.
Some help? Thanks!
P.S. I know that I could also specify exactly what tags I wanted copied, but I figured I would start with brute force and then refine it.