Before I switched from Windows to Ubuntu for my daily computing, I used Adobe's Photoshop Lightroom for processing photos from my DSLR. Adobe made it really straightforward to batch convert from proprietary camera raw files (in my case, .NEF) to DNG. I haven't found any way to convert NEF to DNG in Ubuntu yet. Most photography programs do process NEFs to JPG/TIFF/PNG/etc., but I'm looking for a converter for archival purposes.
Are there any tools available, either standalone or built into another app, that can losslessly batch convert from NEF to DNG?
EDIT: fabricator4 answered the question, but I have since realized that the question itself might not be a good one. There are a few problems with the DNG format that don't necessarily show up in a purely Adobe workflow, but become noticeable when working in a FOSS workflow.
Best Answer
There is an batch converter called DNGconverter. Parts of KDE might be dependencies but it's in the Software Center for installation so that will be taken care of.
Some of the comments on it in software center are saying there's a problem with a work around, you might want to investigate this. There are a few applications like UFRaw that handle raw files very well, you might want to see if there's batch processing capabilities with that one.