Bash’s “set -o vi” vs readline’s own options

bashinputrcvi-mode

I know there is, for readline,

set editing-mode vi

You can put the above option in ~/.inputrc, editing-mode is documented by Readline as

editing-mode (emacs) Controls whether readline begins with a set of key bindings similar to emacs or vi. editing-mode can be set to either emacs or vi.

There is also, for Bash,

set -o vi

According to the Bash documents

vi Use a vi-style line editing interface. This also affects the editing interface used for read -e.

Does Bash's -o vi do anything other than set the appropriate Readline mode? And, if you've already got editing-mode set in your ~/.inputrc does this do anything differently?

Best Answer

The two are identical.

Doing set -o vi in an interactive bash shell calls the set builtin. The C code for the set builtin calls rl_variable_bind("editing-mode", option_name) (where option_name will be vi) which is the Readline library function that sets the command line editing mode.

Setting the command line editing mode on the command line with set -o in the bash shell would override the corresponding setting configured in ~/.inputrc.

Setting the editing mode in ~/.inputrc would set it as the default command line editing mode for any application using the Readline library.

Related Solutions

Bash – How to change readline’s/bash’s meta key

This is the same question I asked I while back, so I'm not taking credit for this, but I had to put

xterm*metaSendsEscape: true
URxvt*altSendsEscape: true

in .Xresources to make Alt work as Meta in both xterm and urxvt. It is a bit contradictory, but it works. So experiment with those options. Also, I had to put

xrdb ~/.Xresources

in .xinitrc for it to work.

Edit: My question: Emacs commands in xterm

Shell Command Line – What Is Meant by a Shell in ‘vi’ Mode or ’emacs’ Mode?

In "vi" mode you can edit/navigate on the current shell prompt like a line in the vi editor. You can look at it like a one-line text file. Analogously in "emacs" mode you can edit/navigate the current command line using (some) of Emacs' shortcuts.

Example

For example in vi-mode you can do something like (in bash):

$ set -o vi
$ ls hello world
<ESC>
bbdw # results in
$ ls world

In emacs-mode you can hit e.g. Ctrl+A to jump at the start of a line (vi: Ctrl+[, 0 or ESC,0). You can turn on emacs mode via set -o emacs (in bash, ksh, zsh etc.).

Readline

A lot of interactive command line programs (including bash) use the readline library. Thus, you can configure which input mode to use (vi or emacs) and other options in one place such that every program using readline has the exact same editing/navigating interface.

For example my readline configuration looks like:

$ cat ~/.inputrc 
set editing-mode vi
set blink-matching-paren on

For example zsh/ksh does not use readline as far as I know, but also support vi/emacs modes that are very much like the bash/readline one.

Of course, the vi/emacs mode in a command line shell is just a subset of the complete editor feature set. Not every feature makes sense in a command line shell, and some features are more complicated to support than others.

Canonical Mode

Before vi/emacs modes of interactive command line shells 'were invented' your shell would use just the canonical mode of your terminal which only provides a limited set of editing commands (e.g. Ctrl+W to delete the last word.