Find the last modified file within a directory

last-modified-file.el

(defun last-modified-file (parent-dir &optional pattern)
  "Get the last modified file under `parent-dir'.
A regex `pattern' can be provided to only look for those that match."
  (let ((default-directory parent-dir))
    (first
     (sort
      (directory-files default-directory 'absolute pattern 'nosort)
      (lambda (x y)
	      (time-less-p (nth 5 (file-attributes y))
		                 (nth 5 (file-attributes x))))))))