Navigate to first diff in diff mode on startup?

Question

Vim diff opens 2 files for diffing, but it doesn't navigate to the first diff section automatically on startup. Can I add something to startup script (like _vimrc) to do this?

Answer 1

]c doesn't jump to the first difference, it jumps to the next difference. If your first difference is on the first line, ]c would jump to the the second one which is not what you want. One could work around that with ]c[c (jump to next difference then jump to previous).

This command:

$ vim -d -c 'norm ]c[c' filea fileb

seems to do what you want.

I don't think it is necessarily a good idea to put that in your startup sciript.

Answer 2

Yes, building on @romainl's answer:

if &diff
  " Jump to next change, then prev change. This puts us on the first change
  " even if it is on line 1.
  autocmd VimEnter * normal! ]c[c
endif

This needs to be on VimEnter (I'm not sure why neither BufReadPost or BufEnter work, maybe someone else knows?) I used the script linked in this answer to determine the earliest event that will work correctly.

You can also add other diff-only mappings in the same block:

  " Jump to next change after getting or putting a chunk
  nnoremap do <Cmd>diffget<CR>]c
  nnoremap dp <Cmd>diffput<CR>]c