Hello first of all sorry of my bad Englisch ( i will use translator ). I tried to make a script that compares two files, if both of them are the same line, delete it, do not know how to go about it, this is an example how it should work: We have 2 files. File1.txt a b lol c d File2.txt b a lol2 d c So lines "a,b,c,d" exist on File1.txt, and on File2.txt, so i want to make program what delete this lines, and after use of program, this files should look like that : File1.txt