I work with tab-delimited files for a living. Because of the same need you have, I created a Python script to do this. It has usage information that is easy to follow (just run it without any arguments).
I hope someone else finds this useful. I have, and use it every month. It can be easily modified to create comma-delimited files, but that's something I never use, so it does tabs. http://milochik.com/shawn/fwconvert.zip Usage: fwconvert -r rulesFile fileName [-t|-f] or cat filename | fwconvert -r rulesFile" (-t|-f) -t (to tab) or -f (to fixed-width) required when piping input to script. Otherwise, it will be auto-determined. Rules file format: fieldStart:fieldLength,fieldStart:fieldLength... Example: 1:3,4:20,24:5 -- http://mail.python.org/mailman/listinfo/python-list
