Emacs: Newline Representations ^M ^J ^L

If emacs shows that, it's probably because you have mixed characters of ^M and ^J and emacs cannot interpret them consistently as newlines.

To fix it, call set-buffer-file-coding-system, then give one of: {mac, dos, unix}. Then, save the file.

If that does not fix it, you can use find ＆ replace to remove it manually.

Call query-replace 【Alt+%】, then type the Carriage Return char by 【Ctrl+q Ctrl+m】 for the find string. For replacement string just press Enter for empty string.

【Ctrl+q】 is the shortcut for the command quoted-insert. It will let you enter the next charater literally. For example, to type a literal tab, press 【Ctrl+q】 then the Tab ⇆ key.

The Carriage Return has caret notation of “^M”, so, press 【Ctrl+q Ctrl+m】 will insert it. Tab is “^I”, so 【Ctrl+q Ctrl+i】 inserts a tab. Same for “^J”

For detail about unprintable ASCII chars, their notations, input methods, notation for input methods, see: Emacs's Key Notations Explained (/r, ^M, C-m, RET, <return>, M-, meta).

Not really. When emacs opens a file, it represent all newline by “^j” (Line Feed; ASCII 10; unix convention), doesn't matter what's the actual newline convention in the file. If emacs displays “^M” (ASCII 13; carriage return), that's because the file has inconsistent line endings.

When you save a file, emacs automatically use the correct newline char when writing the buffer to file, according to the value of “buffer-file-coding-system”.

Also, emacs may automatically add a newline to the end of the file when you save it. Which character it adds depends on the current file encoding system. So, if you manually change the newline char, emacs may add one that is inconsistent to what you expect. The auto adding newline is controlled by the variables “require-final-newline” and “mode-require-final-newline”.

If you want to convert line ending from different OS, always first call set-buffer-file-coding-system, with a value of {mac, dos, unix}. (on Mac OS X, use “unix”.)

Call describe-variable 【F1 v】, then “buffer-file-coding-system”.

Place your cursor on it, then call describe-char.

Open the file, then call set-buffer-file-coding-system 【Ctrl+x Enter f】. When it prompts you for a coding system, type one of: {mac, dos, unix}, when you save the file, it'll be saved with the proper encoding for newlines.

To do it batch on a list of files, use the following lisp code:

(defun to-unix-eol (fPath)
  "Change file's line ending to unix convention."
  (let (myBuffer)
    (setq myBuffer (find-file fPath))
    (set-buffer-file-coding-system 'unix) ; or 'mac or 'dos
    (save-buffer)
    (kill-buffer myBuffer)
   )
)

(mapc 'to-unix-eol
 (list
"~/jane/myfile1"
"~/jane/myfile2"
"~/jane/myfile3"
; …
  )
)

To use the code, first edit the list of files above. Then, select all the code, then call eval-region. That's it.

If you want the function to work on marked files in dired, then use the following code:

(defun to-unix-eol-on-marked-files ()
  "Change to unix line ending for marked (or next arg) files."
  (interactive)
  (mapc 'to-unix-eol (dired-get-marked-files))
)

Select the code, then call eval-region, then call dired, then press m to mark the files you want, then call “to-unix-eol-on-marked-files”.