WIN redirecting STDOUT and STDIN to new spawned CMD console

LanX has asked for the wisdom of the Perl Monks concerning the following question:

this question is related to Prompting for input inside IDE run (was Reading from STDIN) but I think it's worth its own thread

I want a Perl script to write errors via STDERR and receive signals in the first CMD window where it's started and show/get STDOUT/STDIN in a second CMD which was spawned.

For debugging/development.

That's not too unheard off, the second window is similar to a GUI app which writes errors into the original console.

Now I remember achieving similar things with Xterms and TTYs on Linux, but is it also easily possible with Win CMDs?

Searching for "redirecting STDOUT" is always only showing >file stuff for me.

Cheers Rolf
_{(addicted to the 𐍀𐌴𐍂𐌻 Programming Language :)

Wikisyntax for the Monastery}

update

fixed confusion, wrote STDERR where I meant STDIN

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Re: WIN redirecting STDOUT and STDIN to new spawned CMD console by stevieb (Canon) on Mar 28, 2023 at 07:58 UTC
"That's not too unheard off, the second window is similar to a GUI app which writes errors into the original console." This isn't exactly as easy as it sounds, especially given the difficulty of transferring environment from one console to another. In berrybrew, doing what you suggest means having one app (ie. GUI) communicating with a backend that also communicates to another app (CMD window) to display any output. That 'kind of' happens in debug mode, but only artificially. The GUI is typically started from the CMD, so in this case it is the backend that communicates to the other window, but one way or another, you have to start another shell if you want to trap it there. It's unfortunately not as easy as a `tee` If this problem could ever be solved especially if the environment could be carried from one CMD to another, I could remove a couple hundred lines of C# and make great efficiencies :) I have literally been waiting for a solution to this specific question for a long time. I just didn't know how to ask it.	[reply] [d/l]
Re^2: WIN redirecting STDOUT and STDIN to new spawned CMD console by LanX (Saint) on Mar 28, 2023 at 14:00 UTC
Thanks, I didn't know it's that complicated. My approach to Win is to mentally map concepts I know from Linux, even after years. And this doesn't always fit. I also kind of remembered that a child process is inheriting STD-IN/OUT/ERR from the parent. So one of my ideas was that probably it was possible than an app spawns a console as child with "cloned" STDIN and STDOUT, while STDERR is kept to the parent's console. Cheers Rolf _{(addicted to the 𐍀𐌴𐍂𐌻 Programming Language :) Wikisyntax for the Monastery}	[reply]
Re: WIN redirecting STDOUT and STDIN to new spawned CMD console by Corion (Patriarch) on Mar 28, 2023 at 07:25 UTC
Do you really mean "CMD" as in `cmd.exe` or do you mean a new console window? If you mean a console window, see Win32::Console, which allows you to create a (second) console window. I think it doesn't readily have methods to redirect STDIN/STDOUT there, but that should be fairly easy with tied filehandles.	[reply] [d/l]
Re^2: WIN redirecting STDOUT and STDIN to new spawned CMD console by LanX (Saint) on Mar 28, 2023 at 13:05 UTC
kind of had something like this in mind How to perldebug a Term::ReadLine application But have to admit that I haven't tested it on win yet. And maybe misremembered/confused things. Cheers Rolf _{(addicted to the 𐍀𐌴𐍂𐌻 Programming Language :) Wikisyntax for the Monastery}	[reply]
Re: WIN redirecting STDOUT and STDIN to new spawned CMD console by harangzsolt33 (Deacon) on Mar 29, 2023 at 03:37 UTC
What if you redirect stdout to a temp file and then launch a separate perl program whose only job is to monitor this temp file and see if it changes. And if it does change, it reads the last 25 lines from the file and prints it to this terminal window. That way whatever gets written to stdout will be displayed in the terminal window.	[reply]
Re^2: WIN redirecting STDOUT and STDIN to new spawned CMD console by soonix (Chancellor) on Mar 29, 2023 at 06:26 UTC
That would be a very roundabout fashion, but might achieve the goal. Perhaps better with a named pipe instead of a temp file...	[reply]
Re^3: WIN redirecting STDOUT and STDIN to new spawned CMD console by LanX (Saint) on Mar 29, 2023 at 07:58 UTC
> would be a very* roundabout fashion* Well with variations it's just a classic. You start a second console running the application redirecting STDERR to a log file. The first console does a `tail -f` on the log-file With PowerShell in the first window at least that's technically feasible, it has a `tail` like mechanism. ° > Perhaps better with a named pipe Not sure how hard it is to have named pipes on windows. Cheers Rolf _{(addicted to the 𐍀𐌴𐍂𐌻 Programming Language :) Wikisyntax for the Monastery} updates °) `Get-Content -Path ".\err.log" -Wait`	[reply] [d/l] [select]
Re^4: WIN redirecting STDOUT and STDIN to new spawned CMD console by soonix (Chancellor) on Mar 29, 2023 at 08:19 UTC
Re^5: WIN redirecting STDOUT and STDIN to new spawned CMD console by bliako (Abbot) on Mar 29, 2023 at 10:35 UTC

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