NAME

anyevent-mqtt-sub - Perl script for subscribing to an MQTT topic

VERSION

version 1.212810

SYNOPSIS

anyevent-mqtt-sub [options] topic1 [topic2] [topic3] ...

DESCRIPTION

This script subscribes to one or more MQTT topics and prints any messages that it receives to stdout.

OPTIONS

-help

Print a brief help message.

-man

Print the manual page.

-host A.B.C.D

The host running the MQTT service. The default is 127.0.0.1.

-port NNNNN

The port of the running MQTT service. The default is 1883.

-client-id STRING

The client id to use in the connect message. The default is 'NetMQTTpm' followed by the process id of the process. This should be up to 23 characters and only use the characters A-Z, a-z, and 0-9 for maximum compatibility.

-qos N

The QoS level for the published message. The default is 0 (MQTT_QOS_AT_MOST_ONCE).

-verbose

Include more verbose output. Without this option the script only outputs errors and received messages one per line in the form:

topic message

With one -verbose options, publish messages are printed in a form of a summary of the header fields and the payload in hex dump and text form.

With two -verbose options, summaries are printed for all messages sent and received.

-keepalive NNN

The keep alive timer value. Defaults to 120 seconds. For simplicity, it is also currently used as the connection/subscription timeout.

-count NNN

Read the specificed number of MQTT messages and then exit. Default is 0 - read forever.

-one or -1

Short for -count 1. Read one message and exit.

--no-retain

Ignore retained messages. That is, wait for new messages rather than processing existing retained messages.

--code CODE

Use CODE for callback. The caller is responsible for ensuring that the code to be executed is safe - i.e. not "system('rm -rf /');". The code will be called with the following arguments in @_:

The topic of the received message.

The message payload.

The Net::MQTT::Message object for the message.

A condvar that can be emitted to quit the subscribe loop.

The AnyEvent::MQTT object.

An empty hash reference that can be used as a stash.

For example:

my ($topic, $payload, $message, $quitcv, $mqtt, $stash) = @_;
print STDERR $topic, ': ', $payload, "\n";
$quitcv->send if ($stash->{'count'}++ > 10);

If a callback is provided with this option then the builtin callback is no longer called.

SEE ALSO

AnyEvent::MQTT(3)

DISCLAIMER

This is not official IBM code. I work for IBM but I'm writing this in my spare time (with permission) for fun.

AUTHOR

Mark Hindess <soft-cpan@temporalanomaly.com>

COPYRIGHT AND LICENSE

This software is copyright (c) 2014 by Mark Hindess.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.