Hi, I have a text file named a.txt which is consist of houndred/thousand lines. I have another text file named b.txt which is consist of hundred thousand (and growing to millions) of lines. I would like to scan every single line of a.txt and compare it with every single line on b.txt If the line available in b.txt, delete that line on file b.txt so there will be no duplicate line between file a.txt and b.txt What is the best way to do this since the b.txt consist hundred thousand line?