Rational Searches (Unix Power Tools, 3rd Edition)

19.8. Rational Searches

Emacs has, oh, a hundred or so different search commands. (Well, the number's probably more like 32, but who's counting?) There are searches of absolutely every flavor you could ever imagine: incremental searches, word searches,[54] regular-expression searches, and so on.

[54]These are especially nice because they can search for phrases that cross line breaks; most searches assume that all the text you want will all be on the same line. However, you can only search for whole words, and if you use troff or T_EX, Emacs may be confused by your "markup."

However, when it comes to your plain old garden-variety search, Emacs is strangely deficient. There is a simple search that just looks for some arbitrary sequence of characters, but it's rather well hidden. In addition, it lacks one very important feature: you can't search for the same string repeatedly. That is, you can't say "Okay, you found the right sequence of letters; give me the next occurrence"; you have to retype your search string every time.

Go to http://examples.oreilly.com/upt3 for more information on: search.el

I thought this was an incredible pain until a friend of mine wrote a special search command. It's in the file search.el. Just stick this into your directory for Emacs hacks (Section 19.12), and add something like the following to your .emacs file:

;; real searches, courtesy of Chris Genly
;; substitute your own Emacs hack directory for /home/los/mikel/emacs
 (load-file "/home/los/mikel/emacs/search.el")

Now you can type CTRL-s to search forward and CTRL-r to search back. Emacs will prompt you for a search string and start searching when you press RETURN. Typing another CTRL-s or CTRL-r repeats your previous search. When you try this, you'll see one other useful feature: unlike the other Emacs searches, this kind of search displays the "default" (i.e., most recent) search string in the minibuffer. It's exactly the kind of search I want.

It's conceivable that you'll occasionally want incremental searches. You'll have to "rebind" them, though, to use them conveniently. Here are the key bindings that I use:

;; rebind incremental search as ESC-s and ESC-r
 (define-key global-map "\M-s" 'isearch-forward)
 (define-key global-map "\M-r" 'isearch-backward)
 ;; have to rebind ESC s separately for text-mode. It's normally
 ;; bound to 'center-line'.
 (define-key text-mode-map "\M-s" 'isearch-forward)

That is, ESC-s and ESC-r now give you forward and reverse incremental searches. And once you've started an incremental search, CTRL-s and CTRL-r still repeat the previous incremental search, just as they're supposed to.

Of course, now you'll have to rebind the "center-line" command if you're fond of it. In my opinion, it's not worth the trouble. The game of "musical key-bindings" stops here.

-- ML