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


version 1.163170


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


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



Print a brief help message.


Print the manual page.


The host running the MQTT service. The default is


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


The client id to use in the connect message. The default is 'NetMQTTpm' followed by the process id of the process.


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.

With three -verbose options, a hex dump of all data transmitted and received is printed.

-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.


Username to be used for authentication in the connection message.


Password to be used for authentication in the connection message.




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


Mark Hindess <>


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.