dcraw is a linux/Windows command line tool. It can convert RAW-files and that does also include Nikons NEF-files.

Raw photo decoder "dcraw" v8.73
by Dave Coffin, dcoffin a cybercom o net

Usage:  dcraw [OPTION]... [FILE]...

-v        Print verbose messages
-c        Write image data to standard output
-e        Extract embedded thumbnail image
-i        Identify files without decoding them
-i -v     Identify files and show metadata
-z        Change file dates to camera timestamp
-w        Use camera white balance, if possible
-a        Average the whole image for white balance
-A  Average a grey box for white balance
-r  Set custom white balance
-C   Correct chromatic aberration
-b   Adjust brightness (default = 1.0)
-n   Set threshold for wavelet denoising
-k   Set black point
-K  Subtract dark frame (16-bit raw PGM)
-H [0-9]  Highlight mode (0=clip, 1=unclip, 2=blend, 3+=rebuild)
-t [0-7]  Flip image (0=none, 3=180, 5=90CCW, 6=90CW)
-o [0-5]  Output colorspace (raw,sRGB,Adobe,Wide,ProPhoto,XYZ)
-o  Apply output ICC profile from file
-p  Apply camera ICC profile from file or "embed"
-d        Document mode (no color, no interpolation)
-D        Document mode without scaling (totally raw)
-j        Don't stretch or rotate raw pixels
-q [0-3]  Set the interpolation quality
-h        Half-size color image (twice as fast as "-q 0")
-f        Interpolate RGGB as four colors
-s [0-99] Select a different raw image from the same file
-4        Write 16-bit linear instead of 8-bit with gamma
-T        Write TIFF instead of PPM

Create a TIFF file and use the cameras White Balance (WB)

dcraw -w -T DSC_8119.NEF

Create a TIFF file and use the average White Balance (WB) on the picture

dcraw -a -T DSC_8119.NEF

Set the filedate to be the same as the picture date according to the EXIF information

dcraw -z filnavn

Options I often use

dcraw.exe -v -w -H 2 -T DSC_4228.NEF