open(FILE, "test.txt") || die;
{
    local $/ = undef;    #set to 'slurp' mode
    $file = <FILE>;      #read entire file into $file
}
close FILE;

$start = '"';
$end   = '"';

my $inside = 0;
my $oldpos = 0;

while ($file =~ /(?<!\\)(\Q$start\E|\Q$end\E)/g) {
    if ($inside == 0) {
       $oldpos = pos($file) - length($start);
       $inside++;
    } else {
       print substr($file, $oldpos, pos($file)-$oldpos);
       $inside--;
    }
}