Use emacs syntax coloring when not in emacs

Question

Emacs in -nw mode colors source code files, in this screenshot you see how emacs colors the .rb file I opened. Over the weeks/months I've gotten used to the coloring.

Despite how hard I try, there always comes a time when I'm not in emacs, and I'm doing a cat in the Terminal.app bash shell. So much like you can pipe a compact block of json to get nicely indented json, is it possible to pipe a .rb file to some scripts that runs Emacs and extracts the syntax coloring that Emacs uses?

Answer 1

You can use the syntax coloring outside Emacs, two working examples are htmlize for the web and e2ansi for the terminal. For your need, you can use e2ansi-cat provided by e2ansi, here is a screenshot of it:

By the way, if you use Eshell, you can easily get the syntax coloring:

(defun eshell/cat-with-syntax-highlight (filename)
  (let ((existing-buffer (get-file-buffer filename))
        (buffer (find-file-noselect filename)))
    (eshell-print
     (with-current-buffer buffer
       (font-lock-ensure)
       (buffer-string)))
    (unless existing-buffer
      (kill-buffer buffer))
    nil))