I stumbled over a bizarre effect in ActiveState Perl for Windows (in both the version 5.8.7 and 5.10.0), which can be shown as follows:

Consider I have a harmless program cat.pl, which just echoes its STDIN:

# This is cat.pl
while(<>) {
  print;
}
[download]

And then I have a marginally more harmful program ls.pl, which feeds some input to cat.pl and reads its output:

# This is ls.pl
use strict;
use warnings;
use IPC::Open2;
# $^X is the path to my Perl
open2(*OUTPUT,*INPUT,"$^X", "cat.pl") or die "$!";
print INPUT "first line\nsecond line\n";
close INPUT;
my @result=<OUTPUT>;
close OUTPUT;
print "RESULT:\n@result\n";
[download]

When I execute under Solaris or under Cygwin

perl ls.pl
[download]

I get as output

RESULT:
first line
 second line
[download]

But when I do it under Windows, the program hangs, as if it would wait indefinitely for input.

I have no explanation for this odditiy. The only hint, that even under Solaris, respectively Cygwin, something unusual is going on, is the fact that in the (otherwise correct) output, the last line is preceded by a single space.

Any suggestion on what is going on here, and how I could get it running on Windows?

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