To clarify this is what I'd like to do:

Text Before:

key: foo
key: bar
key: baz

Text After:

key: foo bar baz

Wondering if anyone has a good technique for this type of operation (simpler the better). Suspect it might be possible with replace-regexp and some back reference trickery - been trying to figure out a way but no inspiration has hit yet :)

  • What would you do manually? Just do that, recording what you do as a keyboard macro.
    – Drew
    Dec 2, 2018 at 23:28
  • Manually, just replace <newline>key: with an empty string?
    – phils
    Dec 2, 2018 at 23:43
  • The problem with the manual methods is that I have a large number of these - - with different keys and number of entries. I was looking for a more programmatic option like the function suggested by xuchunyang@. Agree though for quick edits these work too Dec 3, 2018 at 0:06
  • I suggest that the question text be edited to provide these clarifications.
    – phils
    Dec 3, 2018 at 2:26

1 Answer 1


Here is a command to merge two lines, if these two lines share a common prefix, don't duplicate it

(defun my-merge-two-lines ()
  "Merge the next line into the current line."
    (let (current-line next-line prefix)
      (setq current-line
            (buffer-substring (line-beginning-position) (line-end-position)))
      (setq next-line
            (buffer-substring (line-beginning-position) (line-end-position)))
      (setq prefix (fill-common-string-prefix current-line next-line))
       (concat current-line " " (substring next-line (length prefix)) "\n")))))

For example, assuming the point is on the first line

key: foo
key: bar
key: baz

run the above command twice, the text becomes

key: foo bar baz

If you like the idea, you can simply use the builtin M-^ (delete-indentation/join-line), note that you need manually set the prefix to "key: " via C-x . (set-fill-prefix).

  • Thanks for the two excellent suggestions! Dec 2, 2018 at 19:49

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