In osicat's fd-streams.lisp, there is a function, make-fd-stream. The sbcl version ignores the pathname parameter, but I'm not sure why. If you set the pathname parameter in the stream, you can then recover the pathname from the stream later on. And if you don't unlink tmp files immediately after creation, you can do stuff like this: (let* ((stream (open-temporary-file :no-unlink t)) (fname (namestring (pathname stream)))) (write-data-to-temp-file stream) (close stream) (do-shell-command-on-temp-file fname) (nix:unlink fname)) Sure, that's not the prettiest thing you'll ever do, but it works pretty well when you need it. If you want osicat to support that use case, I offer a couple small patches that don't ignore pathname in make-fd-stream on sbcl and that allow specifying (:no-unlink t) when opening temporary files. Thanks much.