I'm editing a text in org-mode, several lines are repeated since they where part of different files from the same topic.

I want to use delete-duplicate-lines to delete the repeated lines, however, the command removes the blank lines too, which is something I don't want (otherwise I wouldn't have paragraphs!). I want to ignore certain words that exists alone in lines, for instance, "Resume", it is repeated a lot of times in the text, but I want to keep it since is required.

1 Answer 1


Ignoring blank lines

You can tell delete-duplicate-lines to ignore blank lines by calling it via

C-u C-u C-u M-x delete-duplicate-lines RET

If you don't want to have to hit C-u that many times when you call delete-duplicate-lines, you can wrap it in a custom command and bind that command to a key sequence of your choice:

(defun delete-duplicate-lines-keep-blanks ()
  (delete-duplicate-lines (region-beginning) (region-end) nil nil t))

(global-set-key (kbd "C-c d") 'delete-duplicate-lines-keep-blanks)

Ignoring lines matching regexp

As for the second part of your question, I don't think you can achieve what you want using the built-in version of delete-duplicate-lines. You can, however, use a modified version of the command (which also keeps blank lines by default):

(defun delete-duplicate-lines
    (beg end keep &optional reverse adjacent keep-blanks interactive)
     (list (region-beginning) (region-end)
           (read-string "Keep lines matching regexp: ") ; Prompt for regexp to keep
           (equal current-prefix-arg '(4))
           (equal current-prefix-arg '(16))
           t                                            ; Keep blanks by default
  (let ((lines (unless adjacent (make-hash-table :test 'equal)))
        line prev-line
        (count 0)
        (beg (copy-marker beg))
        (end (copy-marker end)))
      (goto-char (if reverse end beg))
      (if (and reverse (bolp)) (forward-char -1))
      (while (if reverse
             (and (> (point) beg) (not (bobp)))
               (and (< (point) end) (not (eobp))))
        (setq line (buffer-substring-no-properties
                (line-beginning-position) (line-end-position)))
        (if (or (and keep-blanks (string= "" line))
                (string-match keep line))               ; Ignore line if it
                                                        ; matches regexp to keep
            (forward-line 1)
          (if (if adjacent (equal line prev-line) (gethash line lines))
                (delete-region (progn (forward-line 0) (point))
                               (progn (forward-line 1) (point)))
                (if reverse (forward-line -1))
                (setq count (1+ count)))
            (if adjacent (setq prev-line line) (puthash line t lines))
            (forward-line (if reverse -1 1))))))
    (set-marker beg nil)
    (set-marker end nil)
    (when interactive
      (message "Deleted %d %sduplicate line%s%s"
               (if adjacent "adjacent " "")
               (if (= count 1) "" "s")
               (if reverse " backward" "")))

This version of delete-duplicate-lines will prompt you for a regexp and keep all lines that match the regexp. For instance, to keep all lines consisting of the word Resume you would do:

M-x delete-duplicate-lines RET ^Resume$ RET

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