my $text;
{
   open(my $test_fh, '<', 'testfile)
      or die "Unable to open testfile: $!\n";

   local $/;  # Read to end of file.

   $text = <$test_fh>;
}

if ($text =~ /\w+\n\n\w+/) {
   print "reading file test:\n$text\nmatches.\n";
}

##</code><code>##

...

while ($text =~ /\w+\n\n\w+/g) {
   print "reading file test:\n$text\nmatches.\n";
}