The way to distinguish command-mode and insert-mode in Bash's Vi command line editing

in /etc/inputrc (or ~/.inputrc) add this:

set show-mode-in-prompt on

this will prefix your prompt with + while in insert-mode, and : while in command mode in bash 4.3

EDIT:in the latest version of bash 4.4, you will instead get a prompt prefixed with "(ins)" or "(cmd)" by default. but, you can change that:

set vi-ins-mode-string "+"set vi-cmd-mode-string ":"

also, you can use color codes like '\e[1;31m', but surround them with '\1' and '\2' to keep readline happy:

set vi-cmd-mode-string "\1\e[1;31m\2:\1\e[0m\2"

Building on @Isaac Hanson's answer you can set the cursor style to reflect the mode (just like in VIM) by setting these in your .inputrc:

set editing-mode viset show-mode-in-prompt onset vi-ins-mode-string \1\e[6 q\2set vi-cmd-mode-string \1\e[2 q\2# optionally:# switch to block cursor before executing a commandset keymap vi-insertRETURN: "\e\n"

This will give you a beam cursor in insert mode or a block cursor for normal mode.

Other options (replace the number after \e[):

        Ps = 0  -> blinking block.        Ps = 1  -> blinking block (default).        Ps = 2  -> steady block.        Ps = 3  -> blinking underline.        Ps = 4  -> steady underline.        Ps = 5  -> blinking bar (xterm).        Ps = 6  -> steady bar (xterm).

Your terminal must support DECSCURSR (like xterm, urxvt, iTerm2). TMUX also supports these (if you set TERM=xterm-256color outside tmux).

After years of using vi mode in korn shell, I have basically trained myself to just tap ESC a few times before I type any commands, and ESC then i to start typing.

The basic premise being that if you just hit ESC, you know precisely what mode you are in.