find pid

How can I find the pid of an errant file? If I do top, (from home directory) I get a ton of stuff, and if I could expand the window from top to bottom, I'd get even more. top does not seem to take an argument--i.e., if I try top /kmail I get an error message. And if I can't give it an argument, must I just patiently wait until the file I'm looking for comes up, and then hope to catch it before it goes? --doug