Use these codes for the #head or #render methods. ex:
head :ok
render :file => '404.html.erb', :status => :not_found
1xx Informational
100 => :continue
101 => :switching_protocols
102 => :processing
2xx Success
200 => :ok
201 => :created
202 => :accepted
203 => :non_authoritative_information
204 => :no_content
205 => :reset_content
206 => :partial_content
207 => :multi_status
226 => :im_used
3xx Redirection
300 => :multiple_choices
301 => :moved_permanently
302 => :found
303 => :see_other
304 => :not_modified
305 => :use_proxy
307 => :temporary_redirect
4xx Client Error
400 => :bad_request
401 => :unauthorized
402 => :payment_required
403 => :forbidden
404 => :not_found
405 => :method_not_allowed
406 => :not_acceptable
407 => :proxy_authentication_required
408 => :request_timeout
409 => :conflict
410 => :gone
411 => :length_required
412 => :precondition_failed
413 => :request_entity_too_large
414 => :request_uri_too_long
415 => :unsupported_media_type
416 => :requested_range_not_satisfiable
417 => :expectation_failed
422 => :unprocessable_entity
423 => :locked
424 => :failed_dependency
426 => :upgrade_required
5xx Server Error
500 => :internal_server_error
501 => :not_implemented
502 => :bad_gateway
503 => :service_unavailable
504 => :gateway_timeout
505 => :http_version_not_supported
507 => :insufficient_storage
510 => :not_extended
