I have generated a large text file containing filenames and sha-256 hashes using the format below - new line at the end of each line after the hashes.
When I say large - it's in the millions of lines - millions of hashes.
It took me quite a while to generate the hashes - since the files span over 30 hard drives using a duplicate file finding program is impossible - the filenames contain the drive on which the file is stored.
It's time to free up some disk space.
I want to DELETE the lines in the text file that have a unique hash that only occurs once.
I want to KEEP ALL the lines in the text file that have a hash that occurs twice or more.