Ihor Radchenko <yantar92@posteo.net> writes:

> Hello,
>
> I am trying to figure out how to programmatically capture output of a
> multi-line bash script in comint buffer.
>
> Consider:
>
> [yantar92:/tmp] $ 
>> if true
>> then
>> echo "hello"
>> fi
> hello
>
> Each line is submitted to shell via comint-send-input and, AFAIK, the
> result can be collected using `comint-output-filter-functions'.
>
> I expect the `comint-output-filter-functions' to be called on "hello"
> line. However, it does not seem to be the case. Empty "" corresponding
> to "> " PS2 prompts upon sending incomplete script lines are also
> passed.
>
> Is it possible to distinguish the actual script output, empty lines in
> the actual script output, and the incomplete prompts?

You could prepend your multiline command with a dummy
'echo multiline_starts_here' command have your
'comint-output-filter-functions' discard output that arrives before
"multiline_starts_here".

Or maybe inject something like 'oldps=$PS2; PS2=""' before the command
and 'PS2=$oldps' after the command. But whether this works could depend
on the shell, some shells might have something like $PS3 or $RPS1, for
example.

You could also accept-process-output after sending each individual line
separately, but this depends on the user not customizing PS2="" in his
bashrc.

As far as Emacs is concerned, PS1/PS2 prompts and non-prompt process
output is all data, read from a single file descriptor. I don't think
it's possible to distinguish them reliably without the above tricks or
some other heuristics.