I have a word list with a lot of words that I want to convert into a json file. To do this I need to make them strings and add a comma in the end of all words. I figured it would be nice to use regular expression to do this and I know about replace-regexp. What I have tried to do this, beginning with the file:


To match each word I use ^([A-Za-z]+)$. I have tried it in https://regex101.com/ and it seems to work the way as expected. But how do I actually use these matches to add a " in front and back of each word to make strings of them?


I can not find in the documentation how to actually use the matches to add more characters.

Edit: After reading https://www.emacswiki.org/emacs/RegularExpression and experimenting with regex101 I found that the words is group 1, so "\1", (added a comma just to complete the json structure) should work, but it does not

Edit2: Just a more clear example of one of the most promising tries: replace-regexp <RET> ^([A-Za-z]+)$ <RET> "\1",

  • Please consider showing the code you've tried so far. That way, someone can perhaps help with that code or offer another suggestion.
    – Drew
    Commented Aug 8, 2018 at 1:40
  • Sorry I fought I have, will be more specific
    – Salviati
    Commented Aug 8, 2018 at 2:14

2 Answers 2


(and ) are ordinary characters in Emacs RegExp, you need to escape them with a / to make them a group, thus you should try

M-x replace-regexp <RET> ^\([A-Za-z]+\)$ <RET> "\1", <RET>

You can also use

M-x replace-regexp <RET> ^[A-Za-z]+$ <RET> "\&", <RET>

where \& stands for the whole match.


You can just read the file in, split it into lines, and then encode directly to json like this:

(require 'json)

(with-temp-file "words.json"
  (insert (with-temp-buffer (insert-file-contents "words.txt")
                 (split-string (buffer-string) "\n" t)))))

This gives me a json file with these contents.:

  • Great example, but it doesn't really answer the question/request, which was about using replace-regexp. Not sure how much OP wanted to solve the problem vs how much OP wanted to learn about regexps and replace-regexp.
    – Drew
    Commented Aug 8, 2018 at 4:33
  • The answer works well, thank you! But like Drew said I really would like to find a way of doing it with replace-regexp just so I can use it in the future.
    – Salviati
    Commented Aug 8, 2018 at 4:49
  • This is almost an XY problem. You mentioned you need to do X and focused on Y to solve it. But there is a much better way than Y to solve X, and still many issues with Y. For example, what happens if your words have unicode characters in them? Or a space? Or a dash? You might try this instead: Replace regexp: ^.+$ -> "\&", That will wrap spaces too, but handle the other cases. probably some regex guru can figure out how to trim these off. Commented Aug 8, 2018 at 15:10

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