noflo-runtime-msgflo/mosquitto-1.3.1/man/mosquitto_sub.1.xml

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<refentry xml:id="mosquitto_sub" xmlns:xlink="http://www.w3.org/1999/xlink">
	<refmeta>
		<refentrytitle>mosquitto_sub</refentrytitle>
		<manvolnum>1</manvolnum>
		<refmiscinfo class="source">Mosquitto Project</refmiscinfo>
		<refmiscinfo class="manual">Commands</refmiscinfo>
	</refmeta>

	<refnamediv>
		<refname>mosquitto_sub</refname>
		<refpurpose>an MQTT version 3.1 client for subscribing to topics</refpurpose>
	</refnamediv>

	<refsynopsisdiv>
		<cmdsynopsis>
			<command>mosquitto_sub</command>
			<arg><option>-A</option> <replaceable>bind_address</replaceable></arg>
			<arg><option>-c</option></arg>
			<arg><option>-d</option></arg>
			<arg><option>-h</option> <replaceable>hostname</replaceable></arg>
			<arg><option>-i</option> <replaceable>client_id</replaceable></arg>
			<arg><option>-I</option> <replaceable>client id prefix</replaceable></arg>
			<arg><option>-k</option> <replaceable>keepalive time</replaceable></arg>
			<arg><option>-p</option> <replaceable>port number</replaceable></arg>
			<arg><option>-q</option> <replaceable>message QoS</replaceable></arg>
			<arg><option>-R</option></arg>
			<arg><option>-S</option></arg>
			<arg><option>-N</option></arg>
			<arg><option>--quiet</option></arg>
			<arg><option>-v</option></arg>
			<arg>
				<arg><option>-u</option> <replaceable>username</replaceable></arg>
				<arg><option>-P</option> <replaceable>password</replaceable></arg>
			</arg>
			<arg>
				<option>--will-topic</option> <replaceable>topic</replaceable>
				<arg><option>--will-payload</option> <replaceable>payload</replaceable></arg>
				<arg><option>--will-qos</option> <replaceable>qos</replaceable></arg>
				<arg><option>--will-retain</option></arg>
			</arg>
			<group>
				<arg>
					<group choice='req'>
						<arg choice='plain'><option>--cafile</option> <replaceable>file</replaceable></arg>
						<arg choice='plain'><option>--capath</option> <replaceable>dir</replaceable></arg>
					</group>
					<arg><option>--cert</option> <replaceable>file</replaceable></arg>
					<arg><option>--key</option> <replaceable>file</replaceable></arg>
					<arg><option>--tls-version</option> <replaceable>version</replaceable></arg>
					<arg><option>--insecure</option></arg>
				</arg>
				<arg>
					<arg choice='plain'><option>--psk</option> <replaceable>hex-key</replaceable></arg>
					<arg choice='plain'><option>--psk-identity</option> <replaceable>identity</replaceable></arg>
					<arg><option>--tls-version</option> <replaceable>version</replaceable></arg>
				</arg>
			</group>
			<arg choice='opt' rep='repeat'><option>-T</option> <replaceable>filter-out</replaceable></arg>
			<arg choice='plain' rep='repeat'><option>-t</option> <replaceable>message-topic</replaceable></arg>
		</cmdsynopsis>
		<cmdsynopsis>
			<command>mosquitto_sub</command>
			<group choice='plain'>
				<arg><option>--help</option></arg>
			</group>
		</cmdsynopsis>
	</refsynopsisdiv>

	<refsect1>
		<title>Description</title>
		<para><command>mosquitto_sub</command> is a simple MQTT version 3.1
		client that will subscribe to a topic and print the messages that it
		receives.</para>
	</refsect1>

	<refsect1>
		<title>Options</title>
		<variablelist>
			<varlistentry>
				<term><option>-A</option></term>
				<listitem>
					<para>Bind the outgoing connection to a local ip
						address/hostname. Use this argument if you need to
						restrict network communication to a particular
						interface.</para>
				</listitem>
			</varlistentry>
			<varlistentry>
				<term><option>-c</option></term>
				<term><option>--disable-clean-session</option></term>
				<listitem>
					<para>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.</para>
					<para>If using this option, it is recommended that the
					client id is set manually with <option>--id</option></para>
				</listitem>
			</varlistentry>
			<varlistentry>
				<term><option>--cafile</option></term>
				<listitem>
					<para>Define the path to a file containing PEM encoded CA
						certificates that are trusted. Used to enable SSL
						communication.</para>
					<para>See also <option>--capath</option></para>
				</listitem>
			</varlistentry>
			<varlistentry>
				<term><option>--capath</option></term>
				<listitem>
					<para>Define the path to a directory containing PEM encoded CA
						certificates that are trusted. Used to enable SSL
						communication.</para>
					<para>For <option>--capath</option> to work correctly, the
						certificate files must have ".crt" as the file ending
						and you must run "c_rehash &lt;path to capath&gt;" each
						time you add/remove a certificate.</para>
					<para>See also <option>--cafile</option></para>
				</listitem>
			</varlistentry>
			<varlistentry>
				<term><option>--cert</option></term>
				<listitem>
					<para>Define the path to a file containing a PEM encoded
						certificate for this client, if required by the
						server.</para>
					<para>See also <option>--key</option>.</para>
				</listitem>
			</varlistentry>
			<varlistentry>
				<term><option>--ciphers</option></term>
				<listitem>
					<para>An openssl compatible list of TLS ciphers to support
						in the client. See
						<citerefentry><refentrytitle>ciphers</refentrytitle><manvolnum>1</manvolnum></citerefentry>
						for more information.</para>
				</listitem>
			</varlistentry>
			<varlistentry>
				<term><option>-d</option></term>
				<term><option>--debug</option></term>
				<listitem>
					<para>Enable debug messages.</para>
				</listitem>
			</varlistentry>
			<varlistentry>
				<term><option>--help</option></term>
				<listitem>
					<para>Display usage information.</para>
				</listitem>
			</varlistentry>
			<varlistentry>
				<term><option>-h</option></term>
				<term><option>--host</option></term>
				<listitem>
					<para>Specify the host to connect to. Defaults to localhost.</para>
				</listitem>
			</varlistentry>
			<varlistentry>
				<term><option>-i</option></term>
				<term><option>--id</option></term>
				<listitem>
					<para>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
					<option>--id-prefix</option> argument.</para>
				</listitem>
			</varlistentry>
			<varlistentry>
				<term><option>-I</option></term>
				<term><option>--id-prefix</option></term>
				<listitem>
					<para>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
					<option>--id</option> argument.</para>
				</listitem>
			</varlistentry>
			<varlistentry>
				<term><option>--insecure</option></term>
				<listitem>
					<para>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 <emphasis>only</emphasis>. 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.</para>
				</listitem>
			</varlistentry>
			<varlistentry>
				<term><option>-k</option></term>
				<term><option>--keepalive</option></term>
				<listitem>
					<para>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.</para>
				</listitem>
			</varlistentry>
			<varlistentry>
				<term><option>--key</option></term>
				<listitem>
					<para>Define the path to a file containing a PEM encoded
						private key for this client, if required by the
						server.</para>
					<para>See also <option>--cert</option>.</para>
				</listitem>
			</varlistentry>
			<varlistentry>
				<term><option>-N</option></term>
				<listitem>
					<para>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
						<option>-v</option>.</para>
				</listitem>
			</varlistentry>
			<varlistentry>
				<term><option>-p</option></term>
				<term><option>--port</option></term>
				<listitem>
					<para>Connect to the port specified instead of the default 1883.</para>
				</listitem>
			</varlistentry>
			<varlistentry>
				<term><option>-P</option></term>
				<term><option>--pw</option></term>
				<listitem>
					<para>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 <option>--username</option> option.</para>
				</listitem>
			</varlistentry>
			<varlistentry>
				<term><option>--psk</option></term>
				<listitem>
					<para>Provide the hexadecimal (no leading 0x)
						pre-shared-key matching the one used on the broker to
						use TLS-PSK encryption support.
						<option>--psk-identity</option> must also be provided
						to enable TLS-PSK.</para>
				</listitem>
			</varlistentry>
			<varlistentry>
				<term><option>--psk-identity</option></term>
				<listitem>
					<para>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.</para>
				</listitem>
			</varlistentry>
			<varlistentry>
				<term><option>-q</option></term>
				<term><option>--qos</option></term>
				<listitem>
					<para>Specify the quality of service desired for the
					incoming messages, from 0, 1 and 2. Defaults to 0. See
					<citerefentry><refentrytitle>mqtt</refentrytitle><manvolnum>7</manvolnum></citerefentry>
					for more information on QoS.</para>
					<para>The QoS is identical for all topics subscribed to in
					a single instance of mosquitto_sub.</para>
				</listitem>
			</varlistentry>
			<varlistentry>
				<term><option>--quiet</option></term>
				<listitem>
					<para>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 <option>--port</option> without a
					port).</para>
				</listitem>
			</varlistentry>
			<varlistentry>
				<term><option>-R</option></term>
				<listitem>
					<para>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.</para>
				</listitem>
			</varlistentry>
			<varlistentry>
				<term><option>-S</option></term>
				<listitem>
					<para>Use SRV lookups to determine which host to connect
						to. Performs lookups to
						<option>_mqtt._tcp.&lt;host&gt;</option> when used in
						conjunction with <option>-h</option>, otherwise uses
						<option>_mqtt._tcp.&lt;local dns
							domain&gt;</option>.</para>
				</listitem>
			</varlistentry>
			<varlistentry>
				<term><option>-t</option></term>
				<term><option>--topic</option></term>
				<listitem>
					<para>The MQTT topic to subscribe to. See
					<citerefentry><refentrytitle>mqtt</refentrytitle><manvolnum>7</manvolnum></citerefentry>
					for more information on MQTT topics.</para>
					<para>This option may be repeated to subscribe to multiple topics.</para>
				</listitem>
			</varlistentry>
			<varlistentry>
				<term><option>-T</option></term>
				<term><option>--filter-out</option></term>
				<listitem>
					<para>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.</para>
					<para>For example, subscribe to the BBC tree, but suppress output from Radio 3:</para>
					<itemizedlist mark="circle">
						<listitem><para>mosquitto_sub <literal>-t</literal>
								bbc/# <literal>-T</literal>
								bbc/radio3</para></listitem>
					</itemizedlist>
					<para>This option may be repeated to filter out multiple
						topics or topic trees.</para>
				</listitem>
			</varlistentry>
			<varlistentry>
				<term><option>--tls-version</option></term>
				<listitem>
					<para>Choose which TLS protocol version to use when
						communicating with the broker. Valid options are
						<option>tlsv1.2</option>, <option>tlsv1.1</option> and
						<option>tlsv1</option>. The default value is
						<option>tlsv1.2</option>. If the installed version of
						openssl is too old, only <option>tlsv1</option> will be
						available. Must match the protocol version used by the
						broker.</para>
				</listitem>
			</varlistentry>
			<varlistentry>
				<term><option>-u</option></term>
				<term><option>--username</option></term>
				<listitem>
					<para>Provide a username to be used for authenticating with
					the broker. This requires a broker that supports MQTT v3.1.
					See also the <option>--pw</option> argument.</para>
				</listitem>
			</varlistentry>
			<varlistentry>
				<term><option>-v</option></term>
				<term><option>--verbose</option></term>
				<listitem>
					<para>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".</para>
				</listitem>
			</varlistentry>
			<varlistentry>
				<term><option>--will-payload</option></term>
				<listitem>
					<para>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 <option>--will-topic</option>.</para>
				</listitem>
			</varlistentry>
			<varlistentry>
				<term><option>--will-qos</option></term>
				<listitem>
					<para>The QoS to use for the Will. Defaults to 0. This must
					be used in conjunction with <option>--will-topic</option>.</para>
				</listitem>
			</varlistentry>
			<varlistentry>
				<term><option>--will-retain</option></term>
				<listitem>
					<para>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 <option>--will-topic</option>.</para>
				</listitem>
			</varlistentry>
			<varlistentry>
				<term><option>--will-topic</option></term>
				<listitem>
					<para>The topic on which to send a Will, in the event that
					the client disconnects unexpectedly.</para>
				</listitem>
			</varlistentry>
		</variablelist>
	</refsect1>

	<refsect1>
		<title>Wills</title>
		<para>mosquitto_sub can register a message with the broker that will be
		sent out if it disconnects unexpectedly. See
		<citerefentry><refentrytitle>mqtt</refentrytitle><manvolnum>7</manvolnum></citerefentry>
		for more information.</para>
		<para>The minimum requirement for this is to use <option>--will-topic</option> to
		specify which topic the will should be sent out on. This will result in
		a non-retained, zero length message with QoS 0.</para>
		<para>Use the <option>--will-retain</option>, <option>--will-payload</option> and <option>--will-qos</option> arguments to
		modify the other will parameters.</para>
	</refsect1>

	<refsect1>
		<title>Examples</title>
		<para>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.</para>
		<para>Subscribe to temperature information on localhost with QoS 1:</para>
		<itemizedlist mark="circle">
			<listitem><para>mosquitto_sub <literal>-t</literal> sensors/temperature <literal>-q</literal> 1</para></listitem>
		</itemizedlist>
		<para>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.</para>
		<itemizedlist mark="circle">
			<listitem><para>mosquitto_sub <literal>-t</literal> sensors/machines/+/temperature/+</para></listitem>
		</itemizedlist>
		<para>Subscribe to all broker status messages:</para>
		<itemizedlist mark="circle">
			<listitem><para>mosquitto_sub <literal>-v</literal> <literal>-t</literal> \$SYS/#</para></listitem>
		</itemizedlist>
	</refsect1>

	<refsect1>
		<title>Bugs</title>
		<para><command>mosquitto_sub</command> bug information can be found at
		<uri type="webpage">http://launchpad.net/mosquitto</uri></para>
	</refsect1>

	<refsect1>
		<title>See Also</title>
		<simplelist type="inline">
			<member>
				<citerefentry>
					<refentrytitle><link xlink:href="mqtt-7.html">mqtt</link></refentrytitle>
					<manvolnum>7</manvolnum>
				</citerefentry>
			</member>
			<member>
				<citerefentry>
					<refentrytitle><link xlink:href="mosquitto_pub-1.html">mosquitto_pub</link></refentrytitle>
					<manvolnum>1</manvolnum>
				</citerefentry>
			</member>
			<member>
				<citerefentry>
					<refentrytitle><link xlink:href="mosquitto-8.html">mosquitto</link></refentrytitle>
					<manvolnum>8</manvolnum>
				</citerefentry>
			</member>
			<member>
				<citerefentry>
					<refentrytitle><link xlink:href="libmosquitto-3.html">libmosquitto</link></refentrytitle>
					<manvolnum>3</manvolnum>
				</citerefentry>
			</member>
			<member>
				<citerefentry>
					<refentrytitle><link xlink:href="mosquitto-tls-7.html">mosquitto-tls</link></refentrytitle>
					<manvolnum>7</manvolnum>
				</citerefentry>
			</member>
		</simplelist>
	</refsect1>

	<refsect1>
		<title>Acknowledgements</title>
		<para>This product includes software developed by the OpenSSL Project
			for use in the OpenSSL Toolkit. (http://www.openssl.org/)</para>
		<para>This product includes cryptographic software written by Eric
			Young (eay@cryptsoft.com)</para>
		<para>This product includes software written by Tim Hudson
			(tjh@cryptsoft.com)</para>
	</refsect1>

	<refsect1>
		<title>Author</title>
		<para>Roger Light <email>roger@atchoo.org</email></para>
	</refsect1>
</refentry>