Command-line reference

--mqtt_servername <host>

Broker host name or IP.

—

--mqtt_port <port>

Broker port.

1883

--mqtt_version <5|3.1.1>

Protocol version.

5

--mqtt_client_id <id>

Client identifier (generated UUID if omitted).

—

--mqtt_keep_alive <sec>

Keep‑alive interval.

0 (disabled)

--mqtt_transport <TCP|SSL>

Select TCP or TLS.

TCP

--proxy <url>

HTTP/HTTPS forward proxy.

—

--print_hex_bytes

Display payload bytes in hexadecimal.

Off

--help

Show built‑in help.

—

--mqtt_clean_start

Start a new session.

--mqtt_session_expiry_interval <sec>

Persist the session after disconnect (0, 1 – 4294967294, 4294967295).

--mqtt_sub_topic <topic>

Add a subscription (repeatable).

--mqtt_sub_topic_single

Send one SUBSCRIBE per filter.

--mqtt_sub_topic_no_local_option

Ignore messages published by this client (MQTT 5).

--mqtt_sub_topic_retain_as_published

Preserve retain flag on incoming messages (MQTT 5).

--mqtt_sub_topic_retain_handling <0|1|2>

Control retained message delivery (MQTT 5).

--mqtt_unsub_topic <topic>

Remove a subscription (repeatable).

--mqtt_unsub_topic_single

Send one UNSUBSCRIBE per filter.

--mqtt_pub_topic <topic>

Topic for the next message (repeatable).

—

--mqtt_pub_message <text>

Payload text for the most‑recent topic.

—

--mqtt_pub_file <path>

Payload file for the most‑recent topic.

—

--mqtt_pub_qos <0|1|2>

QoS for the most‑recent message.

0

--mqtt_pub_retain

Set the retain flag.

Off

--mqtt_will_topic <topic>

Will topic.

--mqtt_will_message <text>

Will payload.

--mqtt_will_qos <0|1|2>

Will QoS.

--mqtt_will_retain

Retain the will message.

CONNECT

--mqtt_connect_properties

PUBLISH

--mqtt_publish_properties

SUBSCRIBE

--mqtt_subscribe_properties

UNSUBSCRIBE

--mqtt_unsubscribe_properties

DISCONNECT

--mqtt_disconnect_properties

WILL

--mqtt_will_properties

--ssl_ca_file <file>

CA bundle for server verification.

--ssl_allow_untrusted

Skip certificate verification (test only).

--ssl_cert_file <file>

Client certificate (mutual TLS).

--ssl_key_file <file>

Private key for --ssl_cert_file.