Provided by: mosquitto-clients_0.12-1_i386
mosquitto_sub - an mqtt version 3.1 client for subscribing to topics
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 ...
mosquitto_sub is a simple mqtt version 3.1 client that will subscribe
to a topic and print the messages that it receives.
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
If using this option, it is recommended that the client id is
set manually with --id
Enable debug messages.
Specify the host to connect to. Defaults to localhost.
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.
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.
The number of seconds between sending PING commands to the
broker for the purposes of informing it we are still connected
and functioning. Defaults to 60 seconds.
Connect to the port specified instead of the default 1883.
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.
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.
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).
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.
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.
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".
Specify a message that will be stored by the broker and sent out
if this client disconnects unexpectedly. This must be used in
conjunction with --will-topic.
The QoS to use for the Will. Defaults to 0. This must be used in
conjunction with --will-topic.
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.
The topic on which to send a Will, in the event that the client
mosquitto_sub can register a message with the broker that will be sent
out if it disconnects unexpectedly. See mqtt(7) for more information.
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.
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:
· 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.
· mosquitto_sub -t sensors/machines/+/temperature/+
Subscribe to all broker status messages:
· mosquitto_sub -v -t \$SYS/#
mosquitto_sub bug information can be found at
mqtt(7) mosquitto_pub(1) mosquitto(8) libmosquitto(3)
Roger Light <email@example.com>
25 July 2011 mosquitto_sub(1)