The question is general, but here's a specific case:

In LaTeX source files, it doesn't matter if two words are separated by one space character, multiple space characters, or even a linebreak - in the compiled document, the two words are just separated by one space. Many people will insert linebreaks to do manual line wrapping when writing LaTeX.

If I want to search a phrase containing multiple words inside the LaTeX source file, is Emacs able to disregard the white space ambiguities described above when searching?

  • 1
    Does (info "(emacs) Lax Search") answer your question?
    – Basil
    Commented Sep 5, 2021 at 9:34
  • @Basi Thanks for the link, I just need (setq search-whitespace-regexp "[[:space:]\n]+")
    – felix
    Commented Sep 5, 2021 at 9:58
  • Please either add that as an answer or delete the question. Comments can be deleted at any time. Q&A need to stand on their own (only they are searchable). Also: it's possible that this question is a duplicate - please search for that, and if so, delete it. Thx.
    – Drew
    Commented Sep 5, 2021 at 15:09
  • @phils thanks for the language advice, please feel free to suggest alternative wording. (Unfortunately I don't think I can edit the question anymore.)
    – felix
    Commented Sep 6, 2021 at 19:39

1 Answer 1


Following the link of @Basil, here's the needed ELisp code.

(setq search-whitespace-regexp "[[:space:]\n]+"))

To enable this whenever I edit LaTeX documents, I added the following code to my init file.

(defun my-latex-search-setting ()
  (setq search-whitespace-regexp "[[:space:]\n]+"))
(add-hook 'latex-mode-hook #'my-latex-search-setting)

Now if I press Ctrl-s to search for hello world, Emacs will match e.g.

hello    world

as well as

  • 1
    search-whitespace-regexp is a global setting, so it doesn't make sense to set it in a mode hook. You should either set it globally or make it buffer local ((make-local-variable 'search-whitespace-regexp) in the mode hook before the assignment). Commented Sep 7, 2021 at 16:33
  • @Gilles'SO-stopbeingevil' Thanks, I've changed it to (defun my-latex-search-setting () (make-local-variable 'search-whitespace-regexp) (setq search-whitespace-regexp "[[:space:]\n]+"))
    – felix
    Commented Sep 8, 2021 at 18:39

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