display name of file when searching data?

Some sort of black magic?I mean the obvious question would be "Why don't you know the name of the file you are reading?" and i think the answer to that would be helpful.

I still don't get the question. If there are many files, how do you pick one to read from? Or if you read from every one in turn, how do you manage to do that? Whatever you do, once you've got a file to read from, getting its name shouldn't be a lot of trouble.