How can you concatenate two huge files with very little spare disk space? [closed]

Answer 1

time spent figuring out clever solution involving disk-sector shuffling and file-chain manipulation: 2-4 hours

time spent acquiring/writing software to do in-place copy and truncate: 2-20 hours

times median $50/hr programmer rate: $400-$1200

cost of 1TB USB drive: $100-$200

ability to understand the phrase "opportunity cost": priceless