🚀 go-pugleaf

I'm running 18.54 on sunOS 4.0, i only notice the ^M when doing rlogin.
These routines work for me, may help you.
caveat:
  I'm using cmushell mostly.
  I'm not sure if the "a-filter" (marker version) really works.
   "b-filter" does.

(defun a-filter-function (process string)
  "process-filter which strips out extra CR chars from rlogin."
  ;; version using markers
  (let ((buffer (process-buffer process)))
    (when (bufferp buffer)
      (set-buffer buffer)
      (save-excursion
	(goto-char (marker-position (process-mark process)))
	(let ((opoint (point)))
	  ;; need extra char to keep from inserting *at* point
	  (insert-before-markers string " ")
	  (move-marker (process-mark process) (point))
	  (save-restriction
	    (narrow-to-region opoint (point))
	    (goto-char opoint)
	    (replace-string "
	    )
	  (goto-char (marker-position (process-mark process)))
	  (delete-backward-char 1)
	  )))))

(defun b-filter-function (process string)
  "process-filter which strips out extra CR chars from rlogin."
  ;; version using points
  (let ((buffer (process-buffer process)))
    (when (bufferp buffer)
      (set-buffer buffer)
      (let ((opoint (point))
	    (spoint (marker-position (process-mark process)))
	    (length (length string)))
	(goto-char spoint)
	(insert string)
	(save-restriction
	  (narrow-to-region spoint (point))
	  (goto-char spoint)
	  (replace-string "
	  )
	(move-marker (process-mark process) (+ spoint length))
	(if (<= spoint opoint) 
	    (goto-char (+ opoint length))
	    (goto-char opoint))
	))))

;(setq p (get-buffer-process (get-buffer "*cmushell*")))
;(set-process-filter p 'a-filter-function)
;(set-process-filter p 'b-filter-function)
;(set-process-filter p nil)
(defun filter-ctrl-m (arg)
  "Turn Ctrl-M filter on/off for this buffer."
  (interactive "P")
  (let ((proc (get-buffer-process (current-buffer))))
    (if proc
	(if arg 
	    (progn
	      (set-process-filter proc nil)
	      (message "no ^M filter"))
	    (progn
	      (set-process-filter proc 'b-filter-function)
	      (message "filtering out ^M")))
	(error "no process for this buffer"))))