public function setUnixnewlines($newlines)
    {
        $unixnewlines = StringHelper::booleanValue($newlines);
        $this->unixnewlines = $unixnewlines;
        if ($unixnewlines) {
            $this->flags .= ' --unix-newlines ';
        } else {
            $this->flags = str_replace(' --unix-newlines ', '', $this->flags);
        }
    }