Exiting back to normal mode in terminal buffer from Vimscript

Question

<C-\><C-n> is working as (I'd) exepected, but not from a Vimscript.

I am trying to make a script that will:

• open Neovim's :terminal
• run a python script
• exit from the terminal input mode
• manipulate the terminal buffer just as text

I already do that manually everyday. That's why the script would help. (:

But I can't find a way to give the <C-\><C-n> to the terminal buffer.

Here is the most 'consistent piece' achieved so far:

function! AFunction(...)

let firstArg=a:0
let secondArg=a:1
let thirdArg=a:2
let fourthArg=a:3
let fifthArg=a:4

command! -nargs=* AFunctionCommand call Fetching(<f-args>) 
execute ":terminal python a-python-script.py" a:1 a:2 a:3 a:4

endfunction

It does work, but I can't find a way to pass the exit key. The first idea was to concatenate the strings, as mentioned here. Perhaps something that would allow to stablish where is the <cr> (after the arguments):

execute ":terminal python a-python-script.py" a:1 a:2 a:3 a:4 "\<cr>" . '<C-\><C-n>'

If try to do something like:

execute ":terminal python a-python-script.py" a:1 a:2 a:3 a:4
<C-\><C-n>

It doesn't work since terminal has 'nomodifiable' by the default. The same if trying to call a function with the escape keys.

Yes, it is a horrible Vimscript art, and any comment on the code would be really appreciated, but since this is not Code Review, I would be happy with just the reason why doesn't work, or where is my logic not working. (:

Answer 1

:normal cannot be used while in terminal-mode (AKA "insert-mode in a terminal buffer"). Instead feedkeys() can be used (the second \ is not escaped--yet another Vimscript quirk):

:call feedkeys("\<C-\><C-N>")

For your specific case, jamming a feedkeys() call immediately after the :execute doesn't seem to work (could be that "typeahead" is processed before :terminal initializes). Instead, use :stopinsert:

execute ":terminal python a-python-script.py" a:1 a:2 a:3 a:4
stopinsert

Note that the TermOpen autocmd is also available for terminal initialization.