Bash – Make Bash’s vi-mode default to “normal” Vi mode (not “insert”), and place cursor at start of line, mimicking KornShell

bashkshreadlinevi-mode

I'm trying to get Bash to mimic the behaviour of KornShell93 (ksh) when the shells are in Vi command line editing mode.

KornShell defaults to "Vi normal mode" (a.k.a. "command" mode) and it also places the cursor at the very start of the command line when stepping backwards through the command line history. This is in contrast to Bash, which puts you in "Vi insert mode" and at the end of the command line.

In the answers to "Bash vi mode configuration to default to command mode", it pretty much concluded that there's no way to have Bash default to "Vi normal mode" when Vi command line editing is enabled.

This was more than five years ago now, and I wonder if this has changed since then?

And what about automatically placing the cursor at the start of the command line? Is there some to me unbeknown Readline magic that can help me with this?

I'm using Bash version 4.4.5(1)-release compiled from source (the OpenBSD shells/bash port) on OpenBSD-current (January 2017).

Best Answer

It seems that there is no adequate way to insert an Esc in the command line.

While in vi-insert most alpha/numeric keys are used. Esc is quite far away, and any chord (like Alt-j (which works)) seem more complex than desired. So, there is a way to make two keys convert to a configurable string.

The workaround works by using the idea from This answer

Just add this to .inputrc:

 set editing-mode vi
 set vi-ins-mode-string \1\e[6 q\2
 set vi-cmd-mode-string \1\e[2 q\2

 set keymap emacs
 "\ee": vi-editing-mode
 "jk": "\eejk"
 "kj": "\eejk"

 set keymap vi-insert
 "\ee": emacs-editing-mode
 "jk": vi-movement-mode
 "kj": vi-movement-mode

 set keymap vi-command
 "\ee": emacs-editing-mode

By that, no matter where you start either emacs or vi, pressing both jk will place you in vi-command mode at the start of the line.

Additionally, it allows you to switch to emacs mode with Esc-e.

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.

How to kill forward until the end of a big word or to next space character

OK, I have got it work finally.

It turns out that I just have to remap set-mark function to another key sequence (say, \C-x2) and replace the default \C-@ with this new mapping. Then everything works just fine.

Maybe it's a bug that \C-@ doesn't function as expected when appearing in RHS of a Readline macro.

The following is my setup that makes Alt + D delete input forward to the next space or big WORD (in vim jargon).

"\C-x0": vi-eWord
"\C-x1": kill-region
"\C-x2": set-mark
"\eF": "\C-x0\C-f"
"\eD": "\C-x2\eF\C-x1"

Because we didn't use shell-specific Readline function such as shell-forward-word, the key binding works in all applications that utilize Readline library, for example, bash, (i)python, etc.

Best Answer

Related Solutions

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

Example

Readline

Canonical Mode

How to kill forward until the end of a big word or to next space character

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