Dot Emacs: Can frame-title-format show preceding directories?

I'm new to Emacs and loving it so far. In my .emacs I h开发者_开发百科ave the line:

(setq frame-title-format "%b - GNU Emacs")

How can I get it to show the two preceding directories? I tend to have multiple files open with the same name and knowing the directory it is in would be very helpful.

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I think uniquify is a more complete solution to your problem. See http://www.gnu.org/software/emacs/manual/html_node/emacs/Uniquify.html