- Readline is not used in every text field by default. Rather, e.g. MacOS and Readline independently offer a subset of the Emacs keybindings by default (Emacs predates Readline by many years, and I believe Ksh was the first shell to start adding some Emacs bindings to its CLI).
- Many modern CLI apps don’t use Readline, although many of them imitate the default Readline keybindings. Notably, Zsh, Fish, and IPython all use their own line editors that are clearly Readline-inspired but still different. (IPython used to use Readline, but dropped it 5-6 years ago.)
- As other commenters mention, Readline keybindings can be changed: You can switch to Vi keybindings if you want, or define your own in .inputrc. But note that those settings only affect apps that actually use Readline under the hood, so e.g. Zsh and IPython require different settings.
$ set -o viThe .inputrc is specific to readline, and will not be honored by libedit (used extensively on MacOS and BSD-centric systems).
"vi: Allow shell command line editing using the built-in vi editor. Enabling vi mode shall disable any other command line editing mode provided as an implementation extension. It need not be possible to set vi mode on for certain block-mode terminals."
The standard does not specify an emacs option.
https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V...
There's certainly no harm in doing both 'set -o vi' in shell rc and 'set editing-mode vi' in .inputrc
[0]: https://wiki.archlinux.org/title/Readline#Colorized_completi...
Your Postgres psql client will switch to vi mode, which might not be what you intended.
And if a day comes that dash gets linked to libedit on Debian/Ubuntu, only the POSIX standard command will have the desired effect.
The three lines that go in the top of /etc/inputrc on my boxes:
set completion-ignore-case on
set editing-mode vi
set keymap vi-command
export EDITOR=vi
set -o vi