Variable: ff-not-found-hook
ff-not-found-hook is a customizable and buffer-local variable defined
in find-file.el.gz.
Documentation
List of functions to be called if the other file could not be found.
Source Code
;; Defined in /usr/src/emacs/lisp/find-file.el.gz
(defcustom ff-not-found-hook nil
"List of functions to be called if the other file could not be found."
:type 'hook
:local t)