module ActionController::Head

def head(status, options = nil)

See +Rack::Utils::SYMBOL_TO_STATUS_CODE+ for a full list of valid +status+ symbols.

render
return head(:bad_request) unless valid_request?
return head(:method_not_allowed) unless request.post?

It can also be used to return exceptional conditions:

head :created, location: @person

head :created, location: person_path(@person)

significant headers:
This allows you to easily return a response that consists only of
argument is interpreted to be a hash of header names and values.
Returns a response that has no content (merely headers). The options 
def head(status, options = nil)
  if status.is_a?(Hash)
    raise ArgumentError, "#{status.inspect} is not a valid value for `status`."
  end
  status ||= :ok
  if options
    location = options.delete(:location)
    content_type = options.delete(:content_type)
    options.each do |key, value|
      headers[key.to_s.split(/[-_]/).each { |v| v[0] = v[0].upcase }.join("-")] = value.to_s
    end
  end
  self.status = status
  self.location = url_for(location) if location
  if include_content?(response_code)
    unless self.media_type
      self.content_type = content_type || ((f = formats) && Mime[f.first]) || Mime[:html]
    end
    response.charset = false
  end
  self.response_body = ""
  true
end

def include_content?(status) 

def include_content?(status)
  case status
  when 100..199
    false
  when 204, 205, 304
    false
  else
    true
  end
end