#!/usr/bin/env gawk
# source : https://www.linuxquestions.org/questions/programming-9/grep-for-huge-files-826030/#post4066219
# renvoie les lignes de <file1> qui ne sont pas dans <file2>
BEGIN {
	file1 = ARGV[1]
	file2 = ARGV[2]
	delete hash
	while (getline < file1) {
		hash[$0] = 1
	}
	while (getline < file2) {
		if ($0 in hash) {
			delete hash[$0]
		}
	}
	for (a in hash) {
		print a
	}
	exit (0)
}

# à utiliser comme suit
# gawk -f <script> -- <file1> <file2> > <outputfile>

