comint provides Emacs infrastructure for building command interpreters. It’s backing a lot of popular shell/REPL modes - like eshell, inferior-lisp, inf-ruby, inf-clojure, etc.

comint provides a myriad of built-in commands, but somewhat surprisingly it doesn’t feature a command to clear the contents of a comint buffer. Let’s write one such command ourselves!

While there are several way to tackle it, I feel this is the simplest (and the one that makes the best use of comint’s existing functionality):

(defun comint-clear-buffer ()
  (let ((comint-buffer-maximum-size 0))

;; let's bind the new command to a keycombo
(define-key comint-mode-map "\C-c\M-o" #'comint-clear-buffer)

Simple and elegant, right? One day it might even end up being part of comint itself.