Overview

Netcat for MQTT

• Free software: BSD 2-Clause License

Installation

This needs Python 3.6. At the command line:

pip3 install mqttcat

If your system does not provide python 3.6, a more comfortable way is to use the mqtttool Docker container. Please see the Github repo.

Documentation

Usage: mqttcat [OPTIONS] URL

  A MQTT Message filter inspired by netcat and other Unix tools.

  Publishes Messages from STDIN to a MQTT Topic

    -or-

  Subscribes to MQTT Topic and writes messages to STDOUT

  URL - Examples:

      mqtt://hostname/topic     tcp://hostname:1883/topic
      ws://hostname/topic

  Usage Examples:

      mqttcat --echo mqtt://localhost/%23 >/dev/null

      ... will subscribe to all topics ("%23" is urlencoded #), and echo
      them to STDERR for control

      echo "Heart ... beat" | mqttcat --echo --loop --wait=3.3
      mqtt://localhost/heartbeat-topic

      ... will publish "Heart ... beat" every 3.3 seconds to the topic
      "heartbeat-topic"

      mqttcat mqtt://source/ticktock | rq 'filter (a) => { a.payload="tock"
      }' | mqttcat mqtt://destination/tock

      ... subscribe to ticktock topic on host source, filter out the
      messages whose payload is tock,     and forward those to the tock
      topic (using the rq tool https://github.com/dflemstr/rq)

Options:
  --loglevel TEXT             Python loglevel, one of
                              DEBUG,INFO,WARNING,ERROR,CRITICAL
  --echo / --no-echo          Echo MQTT Messages to STDERR
  --source TEXT               File to read MQTT messages to be published (use
                              '-' for STDIN)
  --wait FLOAT                Wait time between publishing messages read from
                              --source in seconds (can be float)
  --loop / --no-loop          Loop message publishing (starting at beginning
                              of file after the end is reached
  --follow / --no-follow      Wait for additional in file after reaching the
                              end (like Unix 'tail -f')
  --destination TEXT          Append JSON-encoded MQTT messages to this file
                              (use '-' for STDOUT)
  --snapshot / --no-snapshot  Keep only the last JSON-encoded message in the
                              file specified with --destination
  --help                      Show this message and exit.

Authors

• Martin Virtel - https://twitter.com/mvtango

This module is part of the Smart Orchestra Project, co-financed by the Federal Ministery of Economics and Technology.