How to undo fill-paragraph in emacs?

I have a text file that is pretty long. Any easy way to "undo" a M-q (fill-paragraph) on a file that was written and saved a while ago?

For example, I want to change this:

They're coming to take me away, ha-haaa!!

They're coming to take me away, ho-ho, hee-hee, ha-haaa

To the funny farm. Where life is beautiful all the time and I'll

be happy to see those nice young men in their clean white

coats and they're coming to take me away, ha-haaa!!!!!

To this:

They're coming to take me away, ha-haaa!! They're coming to take me away, ho-ho, hee-hee, ha-haaa

To the funny farm. Where life is beautiful all the time and I'll be happy to see those开发者_C百科 nice young men in their clean white coats and they're coming to take me away, ha-haaa!!!!!

---

Use the following from my .emacs:

(defun unfill-paragraph ()
  (interactive)
  (let ((fill-column (point-max)))
    (fill-paragraph nil)))

(defun unfill-region ()
  (interactive)
  (let ((fill-column (point-max)))
    (fill-region (region-beginning) (region-end) nil)))

I can't take credit, I googled this years ago.

---

You can set fill-columnn to a really large number, and fill.

C-u 10000 C-x f M-x fill-individual-paragraphs

Or you can use a little custom function:

(defun refill-paragraphs-to-be-one-line ()
  "fill individual paragraphs with large fill column"
  (interactive)
  (let ((fill-column 100000))
    (fill-individual-paragraphs (point-min) (point-max))))

---

When I asked for help on M-Q (as opposed to M-q) in emacs 24.4.1, I got this:

M-Q (translated from <escape> Q) runs the command unfill-paragraph, which is an
interactive Lisp function in `init-util.el'.

It is bound to M-Q.

(unfill-paragraph &optional REGION)

Takes a multi-line paragraph and makes it into a single line of text.

---

C-x f 100000 M-q

This fills exactly one paragraph.

Explanation:

1. C-x f Number: Set a large number (100 000) of characters for the column.
2. M-q: Invoke the fill-paragraph command. (Alternative for multiple paragraphs: M-x fill-individual-paragraphs)

Afterwards, don't forget to revert the column width back to the previous value (here: 78).

C-x f 78