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From: Ihor Radchenko <yantar92@posteo.net>
To: miha@kamnitnik.top
Cc: emacs-devel@gnu.org
Subject: Re: comint-output-filter-functions and multi-line input
Date: Tue, 18 Oct 2022 05:28:39 +0000	[thread overview]
Message-ID: <87pmepg0oo.fsf@localhost> (raw)
In-Reply-To: <87v8oidtzl.fsf@miha-pc>

miha@kamnitnik.top writes:

>> 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".

For context, I am asking because I am trying to figure out how ob-shell
works in Org mode. My multiline command can be arbitrary bash script
containing multiple single- and multi-line commands. It is hard to
figure out which one is which.

> 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.

But will accept-process-output correctly work with PS2=""?

Org uses the following black magic to detect that output is actually
produced:

(org-babel-comint-with-output
		   (session org-babel-sh-eoe-output t body)
		 (dolist (line (append (split-string (org-trim body) "\n")
				       (list org-babel-sh-eoe-indicator)))
		   (insert line)
		   (comint-send-input nil t)
		   (while (save-excursion
			    (goto-char comint-last-input-end)
			    (not (re-search-forward
				  comint-prompt-regexp nil t)))
		     (accept-process-output
		      (get-buffer-process (current-buffer))))))

Note that in addition to accept-process-output, we have to match against
comint-prompt-regexp. Not doing so sometimes lead to infinite loops.

-- 
Ihor Radchenko // yantar92,
Org mode contributor,
Learn more about Org mode at <https://orgmode.org/>.
Support Org development at <https://liberapay.com/org-mode>,
or support my work at <https://liberapay.com/yantar92>



  reply	other threads:[~2022-10-18  5:28 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-10-16  8:48 comint-output-filter-functions and multi-line input Ihor Radchenko
2022-10-17 21:23 ` miha
2022-10-18  5:28   ` Ihor Radchenko [this message]
2022-10-18  7:22     ` miha
2022-10-18  7:35       ` Ihor Radchenko
2022-10-18 11:15         ` miha
2022-10-21  5:32           ` Ihor Radchenko
2022-10-18 13:38         ` Stefan Monnier
2022-10-17 21:27 ` Stefan Monnier
2022-10-18  6:00   ` Ihor Radchenko
2022-10-18 23:22     ` Rudolf Adamkovič
2022-10-21  5:35       ` Ihor Radchenko

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