I suspect that you $line did not hold the whole data. 
local $/;
$_ = <STDIN>;
my $blanks = () =~ /\n\n+/sg;
print "double lines found ( $blanks )\n";

[download]
The example search for lines with two or more \n.
Boris

In reply to Re: search for blank lines by RegEx by borisz
in thread search for blank lines by RegEx by mosh

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