How to search and replace in *open buffers*

Question

I want to interactively search and replace in all (or, preferably, a regexp subset of) my buffers (not files).

Scenario

• Being a pack-rat sort of guy, I never delete my buffers until I'm sure I don't need them anymore (e.g. new project), or until the system crashes and I lose them. So I know that all the files I've modified (the targets of the search and replace) are in a buffer somewhere.
• The files are strewn all over creation so I can't use Dired.
• There are 10k files in scope, so I'd prefer to avoid file-based operations (though I've already wasted so much time on this I've eclipsed the amount of time I would have saved not using the file-based approach).

What I'm doing now

Right now I'm using multi-occur-in-matching-buffers and repeating a query replace for each matching file.

I'm told Icicles will do this, but reading the manual, I can't make heads or tails of how to do it. (I used M-99 M-x icicle-search; I get prompted for a "context", which I can't find a definition for in the manual and furnishes as a completion a list of previous mini-buffer entries, which doesn't make sense to me.) Icicles is far more than I need, but if I have to use it, I will.

Things I've tried

• I tried tags-query-replace but it doesn't work; I always get zero matches, even though it ends bringing up a buffer with a match in plain sight.
• I've read the FAQ (see responses above).

I may end up having to use file-based operations (which are annoying because I have to find and reload each file manually)

Since Icicles supposedly does what I want I thought I'd throw the question out. The other option is to use the Refactor facility in our IDE but that wouldn't be Emacs!! ❤

Answer 1

Ibuffer is what you're looking for.

• M-x ibuffer
• Mark your buffers any way you prefer: using m to mark them manually, % g by regexp content-matching, * M to mark by major mode, or whatever other option which suits your fancy -err needs.
• Use Q to make a regexp search and replace on marked buffers or I for plain search and replace.
• Do the replaces, then go back to ibuffer
• S will save the marked buffers.

There are more ways to achieve the same using other popular tools, but ibuffer is powerful, fit your needs, comes with emacs and can do a lot more than this pretty much effortlessly.

To learn more about it, press ? on a ibuffer buffer.