Batch convert raw NEF files to JPGs with exiftool from Linux command-line. 1, Exiftool have to be installed. Put this pieces of code to a file for example neftojpg.sh. chmod +x neftojppg.sh. Run: ./neftojpg.sh /directory/where/pictures/are/.

NEF to JPG

#!/bin/bash

DIR="$@"

for f in $DIR*.NEF
do
	name=`echo "$f" | sed -e "s/.NEF$//g"`
	exiftool -b -JpgFromRaw "$f" > "${name}.jpg"
done

convert image.nef image.jpg
exiftool -b -JpgFromRaw orignal.NEF > output.jpg

I may be wrong, but ExifTool can only be used to extract JPEGs embedded in the RAW file.
That kind of JPEG is actually a non-fine image to be used as a preview while the software processes the RAW image itself.
Maybe you should go with dcraw, ufraw or even convert for a better result.

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