mosquitto_sub
Section: (1)
Updated: 6 January 2012
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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 functioning. 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 conjunction 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 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.
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:
- •
-
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/#
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>
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- OPTIONS
-
- WILLS
-
- EXAMPLES
-
- BUGS
-
- SEE ALSO
-
- AUTHOR
-
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Time: 23:06:31 GMT, January 06, 2012