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.