Interesting idea... but I can't even get that to return an empty string: 

#!/usr/bin/perl
use Fcntl;

fcntl(STDIN, F_GETFL, my $flags) or die "Couldn't get flags: $!\n";
fcntl(STDIN, F_SETFL, $flags|O_NONBLOCK) or die "Couldn't set flags: $
+!\n";

$_=<STDIN>;

use Data::Dumper;
print Dumper $_;      # --> prints $VAR1 = undef;

[download]

Maybe you can construct a better case (?)

In reply to Re^3: Doubt on defined-ness by almut
in thread Doubt on defined-ness by waldner

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