I'd like to run two instances of IPython in Emacs at the same time, one with Python 2, and the other Python 3: is it something doable or there's something in the way python.el is designed that would prevent it?

1 Answer 1


Yes, that's possible. Add the following code to your init-file (note that you might have to adapt /usr/bin/ipython2 and /usr/bin/ipython to point to appropriate executables for IPython 2 and IPython 3, respectively):

(defun run-python2 ()
  "Run IPython with Python 2."
  (let ((python-shell-buffer-name "Python 2"))
    (run-python "/usr/bin/ipython2 -i" nil t)))

(defun run-python3 ()
  "Run IPython with Python 3."
  (let ((python-shell-buffer-name "Python 3"))
    (run-python "/usr/bin/ipython -i" nil t)))

(global-set-key (kbd "C-c C-2") 'run-python2)
(global-set-key (kbd "C-c C-3") 'run-python3)

With this in place you can launch IPython 2 via C-c C-2 and IPython 3 via C-c C-3. (You can of course change these bindings to your liking.)

  • Thanks a lot, it works very well, and will be very useful to me.
    – cjauvin
    Mar 13, 2015 at 17:21
  • Minor detail: would you happen to also know if it's possible to have different prompt colors for each REPL?
    – cjauvin
    Mar 13, 2015 at 17:25
  • @cjauvin You're welcome :) As for your follow-up question: I'm pretty sure it's possible to have different prompt colors for each REPL. However, ANSI colors are not my area of expertise... I suggest you ask a separate question about changing prompt colors ("How to change prompt color in Python REPL?"). If someone can outline a general approach, I can certainly help you integrate the solution into run-python2 and run-python3.
    – itsjeyd
    Mar 14, 2015 at 20:12
  • Thanks! I found a simple solution: simply adding if sys.version_info[0] < 3: c.PromptManager.in_template = r'{color.Green}In [\#{color.Green}]: ' in my ~/.ipython/profile_default/ipython_config.py.
    – cjauvin
    Mar 15, 2015 at 16:04
  • @cjauvin That's great -- a non-Emacs solution, but hey, if it gets the job done... ;)
    – itsjeyd
    Mar 15, 2015 at 16:18

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