At some point my Vim would undo an entire word when I hit u.

[i]typing some words[C-c][u]

Would result in

typing some

However, the undo granularity seems to have changed to deleting one letter at a time.

[i]typing some words[C-c][u]

Results in

typing some word

I remember reading something about customising undo granularity in Practical Vim, but I can't remember how to control it. Any help appreciated!

  • 3
    There is probably something in your vimrc that does this. I can't replicate it, and can't find anything in the :help files about it ... See: How do I debug my vimrc file?... Also, using <C-c> to exit insert mode may have side-effects (see this) and may be part of the problem ... I would suggest using Esc or <C-[> (see this) Mar 5, 2015 at 13:07

1 Answer 1


Manually breaking the undo sequence

You can manually break the undo sequence in Insert mode with <C-G>u. From the help:

CTRL-G u        break undo sequence, start new change


iHello<C-G>u world!<Esc>u

This will leave you with the text


Breakdown of commands

i                           " Enter Insert mode
 Hello                      " Type 'Hello'
      <C-G>u                " Break the undo sequence
             world!         " Type ' world!'
                   <Esc>    " Return to Normal mode
                        u   " Undo

Automatic solution

Finer-grained undo-level control

Here's a small snippet of VimScript that uses <C-G>u to create undo breaks when you start deleting text, and also when you start entering text again after a deletion.

function! s:start_delete(key)
    let l:result = a:key
    if !s:deleting
        let l:result = "\<C-G>u".l:result
    let s:deleting = 1
    return l:result

function! s:check_undo_break(char)
    if s:deleting
        let s:deleting = 0
        call feedkeys("\<BS>\<C-G>u".a:char, 'n')

augroup smartundo
    autocmd InsertEnter * let s:deleting = 0
    autocmd InsertCharPre * call s:check_undo_break(v:char)
augroup END

inoremap <expr> <BS> <SID>start_delete("\<BS>")
inoremap <expr> <C-W> <SID>start_delete("\<C-W>")
inoremap <expr> <C-U> <SID>start_delete("\<C-U>")


This will work for <BS>, <C-W> (delete a word), and <C-U> (delete to beginning of line). If there are more ways to delete in Insert mode, they can be supported by adding additional inoremap calls at the end.

  • 7
    Only problem is, you don't foresee that you are going to be undoing later (otherwise you won't be doing it in the first place). So you usually end up with a situation where you wish you had used <C-G>u, which is too late already.
    – Shahbaz
    Mar 5, 2015 at 15:40
  • 5
    Yes. Actually something I have been missing myself is this. Sometimes I do this i followed by long sentence followed by backspace to remove part of what I have written (all in insert mode). Then I realize I shouldn't have backspaced and what I had written was fine. I undo, but then the whole inserted text gets undone. So either I am left with none of the long sentence, or the part that is not backspaced. It's impossible to get the backspaced part back. Is there a way to tell vim to break the undo sequence upon backspace? (Now that I say it, maping backspace is an option of course).
    – Shahbaz
    Mar 5, 2015 at 15:46
  • 2
    For future visitors, I also added inoremap <CR> <C-G>u<CR> so that each undo is contained within a single line (no more undoing the whole paragraph that you were typing nonstop).
    – Shahbaz
    Mar 6, 2015 at 11:06
  • 1
    @Shahbaz, absolutely :)
    – tommcdo
    Mar 9, 2015 at 12:14
  • 1
    @Shahbaz "Am I permitted to copy?" See link at the bottom of the page: "user contributions licensed under cc by-sa 3.0 with attribution required"
    – user859
    Feb 14, 2017 at 17:00

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