table of contents
MOSQUITTO_SUB(1) | Commands | MOSQUITTO_SUB(1) |
NAME¶
mosquitto_sub - an MQTT version 3.1 client for subscribing to topicsSYNOPSIS¶
mosquitto_sub [-A bind_address]
[-c] [ -d] [-h hostname]
[-i client_id]
[-I client id prefix] [
-k keepalive time]
[-p port number] [
-q message QoS] [ -R] [-S]
[-N] [ --quiet] [-v]
[[-u username] [
-P password]] [
--will-topic topic [
--will-payload payload] [--will-qos qos] [--will-retain]]
[[{
--cafile file | --capath dir} [--cert file] [--key file] [--tls-version version] [--insecure]]
| [
--psk hex-key --psk-identity identity [
--tls-version version]]]
[-T filter-out...]
-t message-topic...
mosquitto_sub [--help]
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¶
-ABind the outgoing connection to a local ip
address/hostname. Use this argument if you need to restrict network
communication to a particular interface.
-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
--cafile
Define the path to a file containing PEM encoded CA
certificates that are trusted. Used to enable SSL communication.
See also --capath
--capath
Define the path to a directory containing PEM encoded CA
certificates that are trusted. Used to enable SSL communication.
For --capath to work correctly, the certificate files must have
".crt" as the file ending and you must run "c_rehash <path
to capath>" each time you add/remove a certificate.
See also --cafile
--cert
Define the path to a file containing a PEM encoded
certificate for this client, if required by the server.
See also --key.
--ciphers
An openssl compatible list of TLS ciphers to support in
the client. See ciphers(1) for more information.
-d, --debug
Enable debug messages.
--help
Display usage information.
-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.
--insecure
When using certificate based encryption, this option
disables verification of the server hostname in the server certificate. This
can be useful when testing initial server configurations but makes it possible
for a malicious third party to impersonate your server through DNS spoofing,
for example. Use this option in testing only. If you need to resort to
using this option in a production environment, your setup is at fault and
there is no point using encryption.
-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.
--key
Define the path to a file containing a PEM encoded
private key for this client, if required by the server.
See also --cert.
-N
Do not append an end of line character to the payload
when printing. This allows streaming of payload data from multiple messages
directly to another application unmodified. Only really makes sense when not
using -v.
-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.
--psk
Provide the hexadecimal (no leading 0x) pre-shared-key
matching the one used on the broker to use TLS-PSK encryption support.
--psk-identity must also be provided to enable TLS-PSK.
--psk-identity
The client identity to use with TLS-PSK support. This may
be used instead of a username if the broker is configured to do so.
-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).
-R
If this argument is given, messages that are received
that have the retain bit set will not be printed. Messages with retain set are
"stale", in that it is not known when they were originally
published. When subscribing to a wildcard topic there may be a large number of
retained messages. This argument suppresses their display.
-S
Use SRV lookups to determine which host to connect to.
Performs lookups to _mqtt._tcp.<host> when used in conjunction
with -h, otherwise uses _mqtt._tcp.<local dns
domain>.
-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.
-T, --filter-out
Suppress printing of topics that match the filter. This
allows subscribing to a wildcard topic and only printing a partial set of the
wildcard hierarchy.
For example, subscribe to the BBC tree, but suppress output from Radio 3:
--tls-version
•mosquitto_sub -t bbc/# -T bbc/radio3
This option may be repeated to filter out multiple topics or topic trees.Choose which TLS protocol version to use when
communicating with the broker. Valid options are tlsv1.2,
tlsv1.1 and tlsv1. The default value is tlsv1.2. If the
installed version of openssl is too old, only tlsv1 will be available.
Must match the protocol version used by the broker.
-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/mosquittoSEE ALSO¶
mqtt(7), mosquitto_pub(1), mosquitto(8), libmosquitto(3), mosquitto-tls(7)ACKNOWLEDGEMENTS¶
This product includes software developed by the OpenSSL Project for use in the OpenSSL Toolkit. (http://www.openssl.org/) This product includes cryptographic software written by Eric Young (eay@cryptsoft.com) This product includes software written by Tim Hudson (tjh@cryptsoft.com)AUTHOR¶
Roger Light <roger@atchoo.org>08/06/2014 | Mosquitto Project |