Mapping s-tab in vim

Question

I'm trying to set up some basic configuration for vim to make it more useful for myself. One of the things I'm trying to do is map shift+tab to a literal tab character, since my vim configuration sets tabs to be expanded with spaces by default. I attempted to map to the tab char using this reference but no dice.

When I try to strike shift+tab whilst insert mode is active, vim outputs a capital Z for about one second, then removes it and drops out of insert mode with a system error beep. I already tested the shift+tab stroke with ^V and it output ^[[Z into vim as described in the reference, so it's not my OS hijacking the keystroke. Not exactly sure what's causing this; input would be appreciated.

My .vimrc:

" Few basic settings first; I like syntax highlighting & line numbers
syntax on
set number

" Some settings with the list option
" I like to see non-printing characters like Tab & CR
set listchars=tab:▸\ ,eol:¬
set list

" Set tab behaviours: 4 spaces wide, expand <Tab> and >> with spaces
set expandtab
set tabstop=4
set softtabstop=4
set shiftwidth=4
" This line maps shift+tab to a literal tab character
" Because I sometimes need a literal tab
set <s-tab>=    

The very last line shows the ▸ character in vim when set list is on

Answer 1

Try this:

:set t_kB=^[[Z

You don't type the ^[ characters literally; to get the actual escape sequence press control-v then press the escape key. Note that the t_kB option is the same as the <S-Tab> option.

However, this does not map <S-Tab> to <Tab>, it only tells Vim what escape sequence your terminal sends when you press those two keys. But at this point you can map <S-Tab> to <Tab>:

:noremap <S-Tab> <Tab>

To make Vim insert a literal tab character when an option like 'expandtab' is set:

:inoremap <S-Tab> <C-V><Tab>