in reply to Re: Redirecting Output to shell command from within perl (Update "close PIPE")
in thread Redirecting Output to shell command from within perl

After this line: 

open STDOUT, '| wc -l' or die "$! / $^E";

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Anything the program prints, will be piped to wc and the count will show up on the command line when the script exits.

Add: 

open STDERR, '&STDOUT';

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And wc will see STDERR also.

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Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
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Re^3: Redirecting Output to shell command from within perl
by LanX (Saint) on Feb 17, 2018 at 21:58 UTC
    When I do this on Windows with open STDOUT, '|more' , than the effect is significantly different to calling script.pl|more on the cmd line.

    The console is intercepting some keystrokes and using it for it's own commands, for instance I can't quit with q and I can't scroll to next page with bar .

    Haven't tested on linux with "less" yet.

    Cheers Rolf
    (addicted to the Perl Programming Language and ☆☆☆☆ :)
    Wikisyntax for the Monastery

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[d/l]
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      If you redirect output to an interactive command from within a program, I would expect different results to having done it from the command line; but then I wouldn't do it, because it doesn't seem useful, but try this: 

      open STDOUT, '| tee -i null | more';;
print "hello world! $_" for 1.. 1000; 
close STDOUT; 
exit;;

      [download]
      With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
      Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
      "Science is about questioning the status quo. Questioning authority". The enemy of (IT) success is complexity.
      In the absence of evidence, opinion is indistinguishable from prejudice. Suck that fhit
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[d/l]
        my version of Windows doesn't have tee installed

        D:\Users\Rolf\pm>type call_less.pl
open STDOUT, '| tee -i null | more';;
print "hello world! $_\n" for 1.. 100;
close STDOUT;
exit;


D:\Users\Rolf\pm>call_less.pl
Der Befehl "tee" ist entweder falsch geschrieben oder
konnte nicht gefunden werden.

D:\Users\Rolf\pm>

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        Please note that the effect is best seen with small amounts of lines, hence 100.

        > but then I wouldn't do it,

        Neither would I, but I'm not the OP! :)

        Cheers Rolf
        (addicted to the Perl Programming Language and ☆☆☆☆ :)
        Wikisyntax for the Monastery

        UPDATE

        Using (and closing) a dedicated PIPE instead of STDOUT solves the issue for me on Win. see Re: Redirecting Output to shell command from within perl (Update "close PIPE")

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[d/l]

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