I've been messing around a bit with fzf and I'd like to be able to run a command that does something like take the output of diff -w -M origin/main...HEAD --name-only and make the contents available in a preview window.

I've gotten this far, with some copy/paste from the docs:

command! -bang -nargs=* Gdomo
   \ call fzf#vim#grep(
   \   'git diff -w -M origin/main...HEAD --name-only', 0,
   \   fzf#vim#with_preview({'dir': systemlist('git rev-parse --show-toplevel')[0]}), <bang>0))

That gets me the preview window, but selecting any of the files results in:

Error detected while processing function 24[30]..<SNR>53_callback[23]..function 24[30]..<SNR>53_callback:
line   21:
Vim(let):E684: list index out of range: 1

I'm guessing that trying to wrap grep is my first mistake, but I've looked at the plugin code and it's not clear to me what a better approach would be.

  • Aren't you simply looking for :h :GFiles which is built-in in fzf.vim and which opens the not staged files? And if :GFiles is not exactly what you're looking for you can either give it more arguments or look at fzf#vim#gitfiles code which should give your enough inspiration to do what you want.
    – statox
    Apr 16, 2021 at 10:27
  • Thanks. :GFiles is not quite what I'm looking for. I want a preview window with just the files in a branch which have diverged from main, even if there are no unstaged changes. This helps me quickly find, for example, a unit test which I want to tweak or just continue to work on files that I care about which are not currently open in a buffer. I'll have a closer look at fzf#vim#gitfiles.
    – oalders
    Apr 16, 2021 at 17:29

1 Answer 1


It turns out I was overthinking this and I also missed some of the documentation. fzf#run can accept an arbitrary command which returns a list of files.

A working example without a preview window:

command! GDomo
  \ call fzf#run({'source': 'git diff -w -M origin/main...HEAD --name-only', 'sink': 'e'})

A working example with a preview window:

command! GDomo
  \ call fzf#run(
  \   fzf#vim#with_preview(
  \     fzf#wrap({ 'source': 'git diff -w -M origin/main...HEAD --name-only' })
  \   )
  \ )

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