'Write a dnsmasq compatible options file.'

def _output_opts_file(self):

    (options, subnet_index_map) = self._generate_opts_per_subnet()
    options += self._generate_opts_per_port(subnet_index_map)
    name = self.get_conf_file_name('opts')
    file_utils.replace_file(name, '\n'.join(options))
    return name
