Logging

All non-shell commands offer an -l option by which logging to a logfile under ~/.mqtt-cli/logs can be activated
The logfile and log level can be configured in the MQTT-CLI configuration
By specifying the -l option for the shell command the whole shell-session will be logged to a logfile shown at start

If you require debug logging for direct access, the -d (debug) and -v (verbose) options are available for the basic publish and subscribe command

$ mqtt pub -i c1 -t test -m "Hello World" -d -h broker.hivemq.com

Client 'c1@broker.hivemq.com' sending CONNECT
    MqttConnect{keepAlive=60, cleanStart=true, sessionExpiryInterval=0}
Client 'c1@broker.hivemq.com' received CONNACK
    MqttConnAck{reasonCode=SUCCESS, sessionPresent=false, restrictions=MqttConnAckRestrictions{receiveMaximum=10, maximumPacketSize=268435460, topicAliasMaximum=5, maximumQos=EXACTLY_ONCE, retainAvailable=true, wildcardSubscriptionAvailable=true, sharedSubscriptionAvailable=true, subscriptionIdentifiersAvailable=true}} 
Client 'c1@broker.hivemq.com' sending PUBLISH ('Hello World')
    MqttPublish{topic=test, payload=11byte, qos=AT_MOST_ONCE, retain=false}
Client 'c1@broker.hivemq.com' finish PUBLISH
    MqttPublishResult{publish=MqttPublish{topic=test, payload=11byte, qos=AT_MOST_ONCE, retain=false}}

Logging

Direct Logging for Publish and Subscribe