Hi I’m doing some sanity check on my library.
I have some folder that contains grouped images based on file name, raw + in camera JPG.
In the past, using other software (Aperture( I added metadata on the JPG but same metadata was not writter on the raw. I want to copy the metadata from the JPG and paste on the RAW so that digikam can write the xmp for that file. Is there an easy why a part do it mechanically like a stupid monkey? 
Thanks!
If you have both images entered in digikam, you could try to write sidecars for the jpgs, copy the jpg sidecars and give them the name corresponding to the sidecar for the raw file. But proceed at your own risk, and use a small sample first… (copy a few file sets to a separate directory). Though to be useful, that should be scripted. Not too complicated under Linux. But even then, only useful when you have a fair number of files to treat.
This could work in digikam, as the sidecars use the naming scheme <basename>.<ext>.xmp, and not just <basename>.xmp as e.g. Adobe programs do. But check that it doesn’t overwrite some other information.
Another, manual, way would be to have both the raw and the jpeg imported in digikam. Then select the raw first, then the corresponding jpeg. In the “caption” module, you should see the title and description and description for the jpg grayed out. A small edit (I add and delete a space at the end) should turn them white. On “apply”, the data are also written for the raw fiel (note: not “to” the raw!). Jpg tags will show up as well, click on them to write them for both.