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]

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>
[download]

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")

This only uses native commands:

open STDOUT, '| more | more';;
print "hello world! $_" for 1.. 1000; 
exit;;
[download]

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