A simple MQTT version 3.1.1 client that will publish a single message on a topic and exit. More information: https://mosquitto.org/man/mosquitto_pub-1.html.
sensors/temperature to 192.168.1.1 (defaults to localhost) with Quality of Service (QoS) set to 1:mosquitto_pub {{[-h|--host]}} {{192.168.1.1}} {{[-t|--topic]}} {{sensors/temperature}} {{[-m|--message]}} {{32}} {{[-q|--qos]}} {{1}}
sensors/temperature to a remote host on a non-standard port:mosquitto_pub {{[-h|--host]}} {{192.168.1.1}} {{[-p|--port]}} {{1885}} {{[-t|--topic]}} {{sensors/temperature}} {{[-m|--message]}} "{{1266193804 32}}"
switches/kitchen_lights/status to a remote host because there may be a long period of time between light switch events:mosquitto_pub {{[-r|--retain]}} {{[-h|--host]}} "{{iot.eclipse.org}}" {{[-t|--topic]}} {{switches/kitchen_lights/status}} {{[-m|--message]}} "{{on}}"
data.txt) as a message and publish it to sensors/temperature topic:mosquitto_pub {{[-t|--topic]}} {{sensors/temperature}} {{[-f|--file]}} {{data.txt}}
data.txt), by reading from stdin and send the entire input as a message and publish it to sensors/temperature topic:mosquitto_pub {{[-t|--topic]}} {{sensors/temperature}} {{[-s|--stdin-file]}} < {{data.txt}}
stdin as a message and publish it to sensors/temperature topic:{{echo data.txt}} | mosquitto_pub {{[-t|--topic]}} {{sensors/temperature}} {{[-l|--stdin-line]}}