I have 20 folders in one directory ( we will call dir "a"), that contains sub dirs with about 1880 files in them and 20 folders in another directory(and this one "b") with close to the same amount of sub dirs and files. I need to loop thru both sets of directories (a and b) and see if any file/path name in (a) is in (b). that is where I am at. I am able to do it pretty easy with arrays, I just thought it would be faster to use hashes I reckon.