bug#71081: 30.0.50; shell-command-on-region outputs boilerplate text on Windows

[Ihor Radchenko <yantar92@posteo.net>]

Eli Zaretskii <eliz@gnu.org> writes:
>> On 20/05/2024 21:59, Eli Zaretskii wrote:
>> > If it expects the same behavior from cmd.exe as a Posix
>> > shell would produce, the expectation is simply incorrect and
>> > unjustified.
>> 
>> Perhaps we should run something different, or with different arguments, 
>> when on Windows?
>
> Maybe.  But as I said, I don't have a clear understanding of the
> issue.  If I did, perhaps I could give some advice or even suggest a
> code change if required.

The goal is to evaluate a shell script - multi-line string.

For example, given

"cd foo
pwd"

we need to get the output/value separated from the stderr and stderr
output.

Org mode uses the approach borrowed from `shell-command-on-region' -
passing the script as input to shell process (we use
`process-file'). However, as demonstrated by my reproducer, this
approach generates more than just script output.

In theory, we might pass the script as -c '<shell-escaped script body>',
but that's not all the story. We also sometimes want to pass the script
in chunks (via comint interaction).

When using comint, piping commands to shell process input is the only
way to keep the shell running as we send it more commands. However, the
same problem persists - when sending the very first command, cmd.exe
generates its version data, which we cannot easily distinguish from the
rest of the output. We cannot easily see stderr either.

P.S. CCing Matt, ob-shell maintainer.

-- 
Ihor Radchenko // yantar92,
Org mode contributor,
Learn more about Org mode at <https://orgmode.org/>.
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