mosquitto_sub(1)														  mosquitto_sub(1)

NAME

       mosquitto_sub - an mqtt version 3.1 client for subscribing to topics

SYNOPSIS

       mosquitto_sub [-c] [-d] [-h hostname] [-i client_id] [-I client id prefix] [-k keepalive time] [-p port number] [-q message QoS] [--quiet]
		     [-v] [ -u username [-P password] ] [ --will-topic topic [--will-payload payload] [--will-qos qos] [--will-retain] ] -t
		     message topic ...

DESCRIPTION

       mosquitto_sub is a simple mqtt version 3.1 client that will subscribe to a topic and print the messages that it receives.

OPTIONS

       -c, --disable-clean-session
	      Disable  the  'clean session' flag. This means that all of the subscriptions for the client will be maintained after it disconnects,
	      along with subsequent QoS 1 and QoS 2 messages that arrive. When the client reconnects, it will receive all of the queued messages.

	      If using this option, it is recommended that the client id is set manually with --id

       -d, --debug
	      Enable debug messages.

       -h, --host
	      Specify the host to connect to. Defaults to localhost.

       -i, --id
	      The id to use for this client. If not given, defaults to mosquitto_sub_ appended with the process id of the client. Cannot  be  used
	      at the same time as the --id-prefix argument.

       -I, --id-prefix
	      Provide a prefix that the client id will be built from by appending the process id of the client. This is useful where the broker is
	      using the clientid_prefixes option. Cannot be used at the same time as the --id argument.

       -k, --keepalive
	      The number of seconds between sending PING commands to the broker for the purposes of informing it we are still connected and  func-
	      tioning. Defaults to 60 seconds.

       -p, --port
	      Connect to the port specified instead of the default 1883.

       -P, --pw
	      Provide a password to be used for authenticating with the broker. Using this argument without also specifying a username is invalid.
	      This requires a broker that supports MQTT v3.1. See also the --username option.

       -q, --qos
	      Specify the quality of service desired for the incoming messages, from 0, 1 and 2. Defaults to 0. See mqtt(7) for  more  information
	      on QoS.

	      The QoS is identical for all topics subscribed to in a single instance of mosquitto_sub.

       --quiet
	      If  this	argument is given, no runtime errors will be printed. This excludes any error messages given in case of invalid user input
	      (e.g. using --port without a port).

       -t, --topic
	      The mqtt topic to subscribe to. See mqtt(7) for more information on mqtt topics.

	      This option may be repeated to subscribe to multiple topics.

       -u, --username
	      Provide a username to be used for authenticating with the broker. This requires a broker that supports MQTT v3.1.  See also the --pw
	      argument.

       -v, --verbose
	      Print received messages verbosely. With this argument, messages will be printed as "topic payload". When this argument is not given,
	      the messages are printed as "payload".

       --will-payload
	      Specify a message that will be stored by the broker and sent out if this client disconnects unexpectedly. This must be used in  con-
	      junction with --will-topic.

       --will-qos
	      The QoS to use for the Will. Defaults to 0. This must be used in conjunction with --will-topic.

       --will-retain
	      If  given,  if the client disconnects unexpectedly the message sent out will be treated as a retained message.  This must be used in
	      conjunction with --will-topic.

       --will-topic
	      The topic on which to send a Will, in the event that the client disconnects unexpectedly.

WILLS

       mosquitto_sub can register a message with the broker that will be sent out if it disconnects unexpectedly. See mqtt(7)  for  more  informa-
       tion.

       The  minimum  requirement for this is to use --will-topic to specify which topic the will should be sent out on. This will result in a non-
       retained, zero length message with QoS 0.

       Use the --will-retain, --will-payload and --will-qos arguments to modify the other will parameters.

EXAMPLES

       Note that these really are examples - the subscriptions will work if you run them as shown, but there must be something publishing messages
       on those topics for you to receive anything.

       Subscribe to temperature information on localhost with QoS 1:

       o mosquitto_sub -t sensors/temperature -q 1

       Subscribe  to  hard  drive  temperature updates on multiple machines/hard drives. This expects each machine to be publishing its hard drive
       temperature to sensors/machines/HOSTNAME/temperature/HD_NAME.

       o mosquitto_sub -t sensors/machines/+/temperature/+

       Subscribe to all broker status messages:

       o mosquitto_sub -v -t $SYS/#

BUGS

       mosquitto_sub bug information can be found at http://launchpad.net/mosquitto

SEE ALSO

       mqtt(7) mosquitto_pub(1) mosquitto(8) libmosquitto(3)

AUTHOR

       Roger Light <roger@atchoo.org>

								  5 February 2012						  mosquitto_sub(1)