20894fcbce
Some OpenSSL engines (selectable via tls_engine option) may require a password to make use of private keys created with them in the first place. The TPM engine for example, will require a password to access the underlying TPM's Storage Root Key (SRK), which is the root key of a hierarchy of keys associated with a TPM; it is generated within a TPM and is a non-migratable key. Each owned TPM contains a SRK, generated by the TPM at the request of the Owner. [1] By default, the engine will prompt the user to introduce the SRK password before any private keys created with the engine can be used. This could be inconvenient when running on an unattended system. Here's where the new tls_engine_kpass_sha option comes in handy. The user can specify a SHA1 hash of its engine private key password via command line or config file and it will be passed on to the engine directly. This commit adds support for both clients (libmosquitto) and broker. [1] https://goo.gl/qQoXBY Signed-off-by: Nicolás Pernas Maradei <nicopernas@gmail.com>
839 lines
35 KiB
XML
839 lines
35 KiB
XML
<?xml version='1.0' encoding='UTF-8'?>
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<?xml-stylesheet type="text/xsl" href="manpage.xsl"?>
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<refentry xml:id="mosquitto_sub" xmlns:xlink="http://www.w3.org/1999/xlink">
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<refmeta>
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<refentrytitle>mosquitto_sub</refentrytitle>
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<manvolnum>1</manvolnum>
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<refmiscinfo class="source">Mosquitto Project</refmiscinfo>
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<refmiscinfo class="manual">Commands</refmiscinfo>
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</refmeta>
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<refnamediv>
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<refname>mosquitto_sub</refname>
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<refpurpose>an MQTT version 3.1.1/3.1 client for subscribing to topics</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<cmdsynopsis>
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<command>mosquitto_sub</command>
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<group choice='req'>
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<arg choice='plain'>
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<arg><option>-h</option> <replaceable>hostname</replaceable></arg>
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<arg><option>-p</option> <replaceable>port number</replaceable></arg>
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<arg>
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<arg><option>-u</option> <replaceable>username</replaceable></arg>
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<arg><option>-P</option> <replaceable>password</replaceable></arg>
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</arg>
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<arg choice='plain' rep='repeat'><option>-t</option> <replaceable>message-topic</replaceable></arg>
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</arg>
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<arg choice='plain'>
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<arg choice='plain'><option>-L</option> <replaceable>URL</replaceable></arg>
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<arg choice='opt' rep='repeat'><option>-t</option> <replaceable>message-topic</replaceable></arg>
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</arg>
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</group>
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<arg><option>-A</option> <replaceable>bind_address</replaceable></arg>
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<arg><option>-c</option></arg>
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<arg><option>-C</option> <replaceable>msg count</replaceable></arg>
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<arg><option>-d</option></arg>
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<arg><option>-E</option></arg>
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<arg><option>-i</option> <replaceable>client_id</replaceable></arg>
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<arg><option>-I</option> <replaceable>client id prefix</replaceable></arg>
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<arg><option>-k</option> <replaceable>keepalive time</replaceable></arg>
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<arg><option>-N</option></arg>
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<arg><option>-q</option> <replaceable>message QoS</replaceable></arg>
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<group choice='opt'>
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<arg choice='plain'><option>-R</option></arg>
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<arg choice='plain'><option>--retained-only</option></arg>
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</group>
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<arg><option>-S</option></arg>
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<arg choice='opt' rep='repeat'><option>-T</option> <replaceable>filter-out</replaceable></arg>
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<arg choice='opt' rep='repeat'><option>-U</option> <replaceable>unsub-topic</replaceable></arg>
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<arg><option>-v</option></arg>
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<arg><option>-V</option> <replaceable>protocol-version</replaceable></arg>
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<arg><option>-W</option> <replaceable>message processing timeout</replaceable></arg>
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<arg><option>--proxy</option> <replaceable>socks-url</replaceable></arg>
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<arg><option>--quiet</option></arg>
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<arg>
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<option>--will-topic</option> <replaceable>topic</replaceable>
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<arg><option>--will-payload</option> <replaceable>payload</replaceable></arg>
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<arg><option>--will-qos</option> <replaceable>qos</replaceable></arg>
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<arg><option>--will-retain</option></arg>
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</arg>
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<group>
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<arg>
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<group choice='req'>
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<arg choice='plain'><option>--cafile</option> <replaceable>file</replaceable></arg>
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<arg choice='plain'><option>--capath</option> <replaceable>dir</replaceable></arg>
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</group>
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<arg><option>--cert</option> <replaceable>file</replaceable></arg>
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<arg><option>--key</option> <replaceable>file</replaceable></arg>
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<arg><option>--tls-version</option> <replaceable>version</replaceable></arg>
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<arg><option>--tls-engine</option> <replaceable>engine</replaceable></arg>
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<arg><option>--keyform</option>
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<group choice='req'>
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<arg choice='plain'><replaceable>pem</replaceable></arg>
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<arg choice='plain'><replaceable>engine</replaceable></arg>
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</group></arg>
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<arg><option>--tls-engine-kpass-sha</option> <replaceable>kpass-sha</replaceable></arg>
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<arg><option>--insecure</option></arg>
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</arg>
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<arg>
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<arg choice='plain'><option>--psk</option> <replaceable>hex-key</replaceable></arg>
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<arg choice='plain'><option>--psk-identity</option> <replaceable>identity</replaceable></arg>
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<arg><option>--tls-version</option> <replaceable>version</replaceable></arg>
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</arg>
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</group>
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</cmdsynopsis>
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<cmdsynopsis>
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<command>mosquitto_sub</command>
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<group choice='plain'>
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<arg><option>--help</option></arg>
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</group>
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</cmdsynopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para><command>mosquitto_sub</command> is a simple MQTT version 3.1.1
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client that will subscribe to topics and print the messages that
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it receives.</para>
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<para>In addition to subscribing to topics,
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<command>mosquitto_sub</command> can filter out received messages
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so they are not printed (see the <option>-T</option> option) or
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unsubscribe from topics (see the <option>-U</option> option).
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Unsubscribing from topics is useful for clients connecting with
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clean session set to false. </para>
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</refsect1>
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<refsect1>
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<title>Encrypted Connections</title>
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<para><command>mosquitto_sub</command> supports TLS encrypted
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connections. It is strongly recommended that you use an encrypted
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connection for anything more than the most basic setup.</para>
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<para>To enable TLS connections when using x509 certificates, one of
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either <option>--cafile</option> or <option>--capath</option> must
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be provided as an option.</para>
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<para>To enable TLS connections when using TLS-PSK, you must use the
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<option>--psk</option> and the <option>--psk-identity</option>
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options.</para>
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</refsect1>
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<refsect1>
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<title>Options</title>
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<para>The options below may be given on the command line, but may also
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be placed in a config file located at
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<option>$XDG_CONFIG_HOME/mosquitto_sub</option> or
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<option>$HOME/.config/mosquitto_sub</option> with one pair of
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<option>-option <replaceable>value</replaceable></option>
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per line. The values in the config file will be used as defaults
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and can be overridden by using the command line. The exceptions to
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this are <option>-t</option> and <option>-T</option>, which if
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given in the config file will not be overridden. Note also that
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currently some options cannot be negated, e.g.
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<option>-S</option>. Config file lines that have a
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<option>#</option> as the first character are treated as comments
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and not processed any further.</para>
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<variablelist>
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<varlistentry>
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<term><option>-A</option></term>
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<listitem>
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<para>Bind the outgoing connection to a local ip
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address/hostname. Use this argument if you need to
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restrict network communication to a particular
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interface.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-c</option></term>
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<term><option>--disable-clean-session</option></term>
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<listitem>
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<para>Disable the 'clean session' flag. This means that all
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of the subscriptions for the client will be maintained
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after it disconnects, along with subsequent QoS 1 and QoS 2
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messages that arrive. When the client reconnects, it will
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receive all of the queued messages.</para>
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<para>If using this option, the client id must be set
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manually with <option>--id</option></para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--cafile</option></term>
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<listitem>
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<para>Define the path to a file containing PEM encoded CA
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certificates that are trusted. Used to enable SSL
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communication.</para>
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<para>See also <option>--capath</option></para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--capath</option></term>
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<listitem>
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<para>Define the path to a directory containing PEM encoded CA
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certificates that are trusted. Used to enable SSL
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communication.</para>
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<para>For <option>--capath</option> to work correctly, the
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certificate files must have ".crt" as the file ending
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and you must run "openssl rehash <path to capath>" each
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time you add/remove a certificate.</para>
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<para>See also <option>--cafile</option></para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--cert</option></term>
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<listitem>
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<para>Define the path to a file containing a PEM encoded
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certificate for this client, if required by the
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server.</para>
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<para>See also <option>--key</option>.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--ciphers</option></term>
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<listitem>
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<para>An openssl compatible list of TLS ciphers to support
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in the client. See
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<citerefentry><refentrytitle>ciphers</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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for more information.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--tls-engine</option></term>
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<listitem>
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<para>A valid openssl engine id. These can be listed with
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openssl engine command.</para>
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<para>See also <option>--keyform</option>.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--keyform</option></term>
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<listitem>
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<para>Specifies the type of key in use. This could be pem or
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engine. This parameter is useful for example when a TPM
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module is being used and the key has been created with
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it. If not specified, pem keys are assumed</para>
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<para>See also <option>--tls-engine</option>.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--tls-engine-kpass-sha</option></term>
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<listitem>
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<para>SHA1 of private key password when using an SSL engine.
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Some SSL engines may require the usage of a password
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in order to being accessed, like the TPM engine. Instead
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of being prompted for the password, this option allows
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a SHA1 hash of the password to be passed on to the
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engine directly, without user interaction.</para>
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<para>See also <option>--tls-engine</option>.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-C</option></term>
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<listitem>
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<para>Disconnect and exit the program immediately after
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the given count of messages have been received. This
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may be useful in shell scripts where on a single status
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value is required, for example.</para>
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<para>Combine with <option>-R</option> to print only the
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first set of fresh messages (i.e. that does not have
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the retained flag set), or with <option>-T</option> to
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filter which topics are processed.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-d</option></term>
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<term><option>--debug</option></term>
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<listitem>
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<para>Enable debug messages.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-E</option></term>
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<listitem>
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<para>If this option is given,
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<command>mosquitto_sub</command> will exit immediately
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that all of its subscriptions have been acknowledged by
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the broker. In conjunction with <option>-c</option>
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this allows a durable client session to be initialised
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on the broker for future use without requiring any
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messages to be received.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-F</option></term>
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<listitem>
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<para>Specify output printing format. This option allows
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you to choose what information from each message is
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printed to the screen. See the <link
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linkend='outputformat'>Output Format</link> section
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below for full details.</para>
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<para>This option overrides the <option>-v</option> option,
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but does not override the <option>-N</option>
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option.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--help</option></term>
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<listitem>
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<para>Display usage information.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-h</option></term>
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<term><option>--host</option></term>
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<listitem>
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<para>Specify the host to connect to. Defaults to localhost.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-i</option></term>
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<term><option>--id</option></term>
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<listitem>
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<para>The id to use for this client. If not given, defaults
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to mosquitto_sub_ appended with the process id of the
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client. Cannot be used at the same time as the
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<option>--id-prefix</option> argument.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-I</option></term>
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<term><option>--id-prefix</option></term>
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<listitem>
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<para>Provide a prefix that the client id will be built
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from by appending the process id of the client. This is
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useful where the broker is using the clientid_prefixes
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option. Cannot be used at the same time as the
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<option>--id</option> argument.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--insecure</option></term>
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<listitem>
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<para>When using certificate based encryption, this option
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disables verification of the server hostname in the
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server certificate. This can be useful when testing
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initial server configurations but makes it possible for
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a malicious third party to impersonate your server
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through DNS spoofing, for example. Use this option in
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testing <emphasis>only</emphasis>. If you need to
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resort to using this option in a production
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environment, your setup is at fault and there is no
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point using encryption.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-k</option></term>
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<term><option>--keepalive</option></term>
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<listitem>
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<para>The number of seconds between sending PING commands
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to the broker for the purposes of informing it we are still
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connected and functioning. Defaults to 60 seconds.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--key</option></term>
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<listitem>
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<para>Define the path to a file containing a PEM encoded
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private key for this client, if required by the
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server.</para>
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<para>See also <option>--cert</option>.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-L</option></term>
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<term><option>--url</option></term>
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<listitem>
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<para>Specify specify user, password, hostname, port and
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topic at once as a URL. The URL must be in the form:
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mqtt(s)://[username[:password]@]host[:port]/topic</para>
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<para>If the scheme is mqtt:// then the port defaults to
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1883. If the scheme is mqtts:// then the port defaults
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to 8883.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-N</option></term>
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<listitem>
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<para>Do not append an end of line character to the payload
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when printing. This allows streaming of payload data
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from multiple messages directly to another application
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unmodified. Only really makes sense when not using
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<option>-v</option>.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-p</option></term>
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<term><option>--port</option></term>
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<listitem>
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<para>Connect to the port specified. If not given, the
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default of 1883 for plain MQTT or 8883 for MQTT over
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TLS will be used.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>-P</option></term>
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<term><option>--pw</option></term>
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<listitem>
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<para>Provide a password to be used for authenticating with
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the broker. Using this argument without also specifying
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a username is invalid. See also the
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<option>--username</option> option.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--proxy</option></term>
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<listitem>
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<para>Specify a SOCKS5 proxy to connect through. "None" and
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"username" authentication types are supported. The
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<option>socks-url</option> must be of the form
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<option>socks5h://[username[:password]@]host[:port]</option>.
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The protocol prefix <option>socks5h</option> means that
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hostnames are resolved by the proxy. The symbols %25,
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%3A and %40 are URL decoded into %, : and @
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respectively, if present in the username or
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password.</para>
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<para>If username is not given, then no authentication is
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attempted. If the port is not given, then the default
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of 1080 is used.</para>
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<para>More SOCKS versions may be available in the future,
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depending on demand, and will use different protocol
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prefixes as described in <citerefentry>
|
|
<refentrytitle>curl</refentrytitle>
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<manvolnum>1</manvolnum> </citerefentry>.</para>
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</listitem>
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</varlistentry>
|
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<varlistentry>
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<term><option>--psk</option></term>
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<listitem>
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<para>Provide the hexadecimal (no leading 0x)
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pre-shared-key matching the one used on the broker to
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use TLS-PSK encryption support.
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<option>--psk-identity</option> must also be provided
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to enable TLS-PSK.</para>
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</listitem>
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</varlistentry>
|
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<varlistentry>
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<term><option>--psk-identity</option></term>
|
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<listitem>
|
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<para>The client identity to use with TLS-PSK support. This
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may be used instead of a username if the broker is
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configured to do so.</para>
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</listitem>
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</varlistentry>
|
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<varlistentry>
|
|
<term><option>-q</option></term>
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|
<term><option>--qos</option></term>
|
|
<listitem>
|
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<para>Specify the quality of service desired for the
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incoming messages, from 0, 1 and 2. Defaults to 0. See
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|
<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>--retained-only</option></term>
|
|
<listitem>
|
|
<para>If this argument is given, only messages that are
|
|
received that have the retain bit set will be printed.
|
|
Messages with retain set are "stale", in that it is not
|
|
known when they were originally published. With this
|
|
argument in use, the receipt of the first non-stale
|
|
message will cause the client to exit.</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.<host></option> when used in
|
|
conjunction with <option>-h</option>, otherwise uses
|
|
<option>_mqtt._tcp.<local dns
|
|
domain></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. See also the <option>--pw</option>
|
|
argument.</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><option>-U</option></term>
|
|
<term><option>--unsubscribe</option></term>
|
|
<listitem>
|
|
<para>A topic that will be unsubscribed from. This may be
|
|
used on its own or in conjunction with the
|
|
<option>--topic</option> option and only makes sense
|
|
when used in conjunction with
|
|
<option>--clean-session</option>.</para>
|
|
<para>If used with <option>--topic</option> then
|
|
subscriptions will be processed before
|
|
unsubscriptions.</para>
|
|
<para>Note that it is only possible to unsubscribe from
|
|
subscriptions that have previously been made. It is not
|
|
possible to punch holes in wildcard subscriptions. For
|
|
example, subscribing to <option>sensors/#</option> and
|
|
then unsubscribing from
|
|
<option>sensors/+/temperature</option> as shown below
|
|
will still result in messages matching the
|
|
<option>sensors/+/temperature</option> being delivered
|
|
to the client.</para>
|
|
<itemizedlist mark="circle">
|
|
<listitem><para>mosquitto_sub <literal>-t</literal> sensors/# <literal>-U</literal> sensors/+/temperature <literal>-v</literal></para></listitem>
|
|
</itemizedlist>
|
|
|
|
<para>Note also that because retained messages are
|
|
published by the broker on receipt of a SUBSCRIBE
|
|
command, subscribing and unsubscribing to the same
|
|
topic may result in messages being received at the
|
|
client.</para>
|
|
|
|
<para>This option may be repeated to unsubscribe from multiple topics.</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>-V</option></term>
|
|
<term><option>--protocol-version</option></term>
|
|
<listitem>
|
|
<para>Specify which version of the MQTT protocol should be
|
|
used when connecting to the rmeote broker. Can be
|
|
<option>mqttv311</option> or <option>mqttv31</option>.
|
|
Defaults to <option>mqttv311</option>.</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><option>-W</option></term>
|
|
<listitem>
|
|
<para>Provide a timeout as an integer number of seconds.
|
|
mosquitto_sub will stop processing messages and
|
|
disconnect after this number of seconds has
|
|
passed. The timeout starts just after the client has
|
|
connected to the broker.</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 id='outputformat'>
|
|
<title>Output format</title>
|
|
<para>There are three ways of formatting the output from mosquitto_sub.
|
|
In all cases a new-line character is appended for each message
|
|
received unless the <option>-N</option> argument is passed to
|
|
mosquitto_sub.</para>
|
|
<para>Payload-only is the default output format and will
|
|
print the payload exactly as it is received.</para>
|
|
<para>Verbose mode is activated with <option>-v</option> and prints the
|
|
message topic and the payload, separated by a space.</para>
|
|
<para>The final option is formatted output, which allows the user to
|
|
define a custom output format. The behaviour is controlled with
|
|
the <option>-F format-string</option> option. The format string is
|
|
a free text string where interpreted sequences are replaced by
|
|
different parameters. The available interpreted sequences are
|
|
described below.</para>
|
|
<para>Three characters are used to start an interpreted sequence:
|
|
<option>%</option>, <option>@</option> and <option>\</option>.
|
|
Sequences starting with <option>%</option> are either parameters
|
|
related to the MQTT message being printed, or are helper sequences
|
|
to avoid the need to type long date format strings for example.
|
|
Sequences starting with <option>@</option> are passed to the
|
|
<citerefentry><refentrytitle>strftime</refentrytitle><manvolnum>3</manvolnum></citerefentry>
|
|
function (with the @ replaced with a % - note that only the
|
|
character immediately after the @ is passed to strftime). This
|
|
allows the construction of a wide variety of time based outputs.
|
|
The output options for strftime vary from platform to platform, so
|
|
please check what is available for your platform. mosquitto_sub
|
|
does provide one extension to strftime which is
|
|
<option>@N</option>, which can be used to obtain the number of
|
|
nanoseconds passed in the current second. The resolution of this
|
|
option varies depending on the platform. The final sequence
|
|
character is <option>\</option>, which is used to input some
|
|
characters that would otherwise be difficult to enter.</para>
|
|
|
|
<refsect2>
|
|
<title>MQTT related parameters</title>
|
|
<itemizedlist mark="circle">
|
|
<listitem><para><option>%%</option> a literal %.</para></listitem>
|
|
<listitem><para><option>%l</option> the length of the payload in bytes.</para></listitem>
|
|
<listitem><para><option>%m</option> the message id (only relevant for messages with QoS>0).</para></listitem>
|
|
<listitem><para><option>%p</option> the payload raw bytes (may produce non-printable characters depending on the payload).</para></listitem>
|
|
<listitem><para><option>%q</option> the message QoS.</para></listitem>
|
|
<listitem><para><option>%r</option> the retained flag for the message.</para></listitem>
|
|
<listitem><para><option>%t</option> the message topic.</para></listitem>
|
|
<listitem><para><option>%x</option> the payload with each byte as a hexadecimal number (lower case).</para></listitem>
|
|
<listitem><para><option>%X</option> the payload with each byte as a hexadecimal number (upper case).</para></listitem>
|
|
</itemizedlist>
|
|
</refsect2>
|
|
|
|
<refsect2>
|
|
<title>Helpers</title>
|
|
<itemizedlist mark="circle">
|
|
<listitem><para><option>%I</option> ISO-8601 format date and time, e.g. 2016-08-10T09:47:38+0100</para></listitem>
|
|
<listitem><para><option>%j</option> JSON output of message
|
|
parameters and timestamp, with a quoted and escaped
|
|
payload. For example
|
|
<code>{"tst":1470825369,"topic":"greeting","qos":0,"retain":0,"payload":"hello
|
|
world"}</code></para></listitem>
|
|
<listitem><para><option>%J</option> JSON output of message
|
|
parameters and timestamp, with a non-quoted and
|
|
non-escaped payload - this means the payload must
|
|
itself be valid JSON. For example:
|
|
<code>{"tst":1470825369,"topic":"foo","qos":0,"retain":0,"payload":{"temperature":27.0,"humidity":57}}</code>.</para></listitem>
|
|
<listitem><para><option>%I</option> ISO-8601 format date and time, e.g. 2016-08-10T09:47:38+0100</para></listitem>
|
|
<listitem><para><option>%U</option> Unix timestamp with nanoseconds, e.g. 1470818943.786368637</para></listitem>
|
|
</itemizedlist>
|
|
</refsect2>
|
|
|
|
<refsect2>
|
|
<title>Time related parameters</title>
|
|
<itemizedlist mark="circle">
|
|
<listitem><para><option>@@</option> a literal @.</para></listitem>
|
|
<listitem><para><option>@X</option> pass the character represented
|
|
by <option>X</option> to the strftime function as
|
|
<option>%X</option>. The options supported are platform
|
|
dependent.</para></listitem>
|
|
<listitem><para><option>@N</option> the number of nanoseconds that
|
|
have passed in the current second, with varying timing
|
|
resolution depending on platform.</para></listitem>
|
|
</itemizedlist>
|
|
</refsect2>
|
|
|
|
<refsect2>
|
|
<title>Escape characters</title>
|
|
<itemizedlist mark="circle">
|
|
<listitem><para><option>\\</option> a literal \.</para></listitem>
|
|
<listitem><para><option>\0</option> a null character. Can be used
|
|
to separate different parameters that may contain spaces
|
|
(e.g. topic, payload) so that processing with tools such as
|
|
<citerefentry><refentrytitle>xargs</refentrytitle><manvolnum>1</manvolnum></citerefentry>
|
|
is easier.</para></listitem>
|
|
<listitem><para><option>\a</option> alert/bell.</para></listitem>
|
|
<listitem><para><option>\e</option> the escape sequence, which can
|
|
be used with ANSI colour codes to provide coloured output
|
|
for example.</para></listitem>
|
|
<listitem><para><option>\n</option> end of line.</para></listitem>
|
|
<listitem><para><option>\r</option> carriage return.</para></listitem>
|
|
<listitem><para><option>\t</option> horizontal tab.</para></listitem>
|
|
<listitem><para><option>\v</option> vertical tab.</para></listitem>
|
|
</itemizedlist>
|
|
</refsect2>
|
|
</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>
|
|
|
|
<para>Specify the output format as "ISO-8601 date : topic : payload in hex"</para>
|
|
<itemizedlist mark="circle">
|
|
<listitem><para>mosquitto_sub <literal>-F '@Y-@m-@dT@H:@M:@S@z : %t : %x'</literal> <literal>-t</literal> '#'</para></listitem>
|
|
</itemizedlist>
|
|
|
|
<para>Specify the output format as "seconds since epoch.nanoseconds : retained flag : qos : mid : payload length"</para>
|
|
<itemizedlist mark="circle">
|
|
<listitem><para>mosquitto_sub <literal>-F '%@s.@N : %r : %q : %m : %l'</literal> <literal>-q 2</literal> <literal>-t</literal> '#'</para></listitem>
|
|
</itemizedlist>
|
|
|
|
<para>Topic and payload output, but with colour where supported.</para>
|
|
<itemizedlist mark="circle">
|
|
<listitem><para>mosquitto_sub <literal>-F '\e[92m%t \e[96m%p\e[0m'</literal> <literal>-q 2</literal> <literal>-t</literal> '#'</para></listitem>
|
|
</itemizedlist>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>Files</title>
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><filename>$XDG_CONFIG_HOME/mosquitto_sub</filename></term>
|
|
<term><filename>$HOME/.config/mosquitto_sub</filename></term>
|
|
<listitem>
|
|
<para>Configuration file for default options.</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>Bugs</title>
|
|
<para><command>mosquitto</command> bug information can be found at
|
|
<ulink url="https://github.com/eclipse/mosquitto/issues"/></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>Author</title>
|
|
<para>Roger Light <email>roger@atchoo.org</email></para>
|
|
</refsect1>
|
|
</refentry>
|