How do I use vi keys in ipython under *nix?

In case someone's wandering in here recently, IPython 5.0 switched from readline to prompt_toolkit, so an updated answer to this question is to pass an option:

$ ipython --TerminalInteractiveShell.editing_mode=vi

... or to set it globally in the profile configuration (~/.ipython/profile_default/ipython_config.py; create it with ipython profile create if you don't have it) with:

c.TerminalInteractiveShell.editing_mode = 'vi'

Looks like a solution works for many other readline compatible apps:

Set the following in your ~/.inputrc file:

set editing-mode viset keymap viset convert-meta on

Source: http://www.jukie.net/bart/blog/20040326082602

You can also interactively switch between Vi-mode and Emacs mode. According to the the readline docs to switch between them you are supposed to be able to use the M-C-j key combination but that only seems to allow me to switch to vi-mode - on my Mac (where ESC is used as the 'Meta' key) it is: ESC+CTRL+j. To switch back to Emacs mode one can use C-e but that didn't appear to work for me - I had to instead do M-C-e - on my Mac it is: ESC+CTRL+e.

FYI my ~/.inputrc is set up as follows:

set meta-flag onset input-meta onset convert-meta offset output-meta on