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Editorial Team
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Asked: 2026-05-18T06:01:56+00:00

At the moment, I have a process-buffer which is utf-8-auto (emacs modeline reports the

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At the moment, I have a process-buffer which is utf-8-auto (emacs modeline reports the buffer as utf-8-auto-dos) with CRLF style newlines. When I write multi-line text into the buffer via a process-send-region or process-send-string each line is suffixed with ^M.

What makes this problem odd is that text written to the process-buffer directly from the process, does not contain ^M‘s.

It doesn’t seem to make any difference where the source text comes from, in fact, even a multi-line region marked and sent that already appears in the process buffer (that doesn’t contain ^M) will have them when sent.

(Note the source text for the process-send-region will always come from a Emacs buffer, process-send-string, when multi-line will be from the Windows clipboard interface to the killring, or again from an Emacs buffer to killring.)

I should also add that the incoming text to the buffer is parsed by a after-change-functions hook (to do some colorisation based on input) so a last resort I’d do an additional regexp-replace-in-string on this incoming text as part of that hook function, I’d like to avoid that because it seems wrong, but I’ll add it as a hacky solution if nothing else works.

Addendum

I updated the encoding settings for the buffer and the process to use utf-8-dos instead of utf-8-auto and the ^M‘s vanished.

So in the buffer setup part of my app, I did…

(switch-to-buffer "sock-buffer")
(set-process-coding-system (get-process sock-process) 'utf-8-dos 'utf-8-dos)
(set-buffer-file-coding-system 'utf-8-dos nil)
(set-buffer-process-coding-system 'utf-8-dos 'utf-8-dos)

Then reduced this to just…

(switch-to-buffer "sock-buffer")
(set-buffer-process-coding-system 'utf-8-dos 'utf-8-dos)

And everything worked fine.

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1 Answer

  1. Editorial Team

    This is because those files are in DOS/Windows line endings. You can use C-x [Enter] f unix [Enter] to convert them to the Unix encoding.

    ^L is a page break. I’ve seen them some times to separate different parts of source code (for old-fashioned listings in a text printer), or in text documentation to insert an actual “new page” command.

    As of the update, here you can see that you have to select set-process-coding-system to the correct coding system.

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