mqttui-read-one(1)          General Commands Manual         mqttui-read-one(1)

NAME
       mqttui-read-one - Wait for the first message on the given topic(s) and
       return its payload to stdout

SYNOPSIS
       mqttui read-one [-r|--ignore-retained] [--only] [-p|--pretty] [--qos]
       [-b|--broker] [-u|--username] [--password] [-i|--client-id] [--ca-cert]
       [--client-cert] [--client-private-key] [--insecure] [-h|--help] [TOPIC]

DESCRIPTION
       Wait for the first message on the given topic(s) and return its payload
       to stdout.

       Returns exactly one payload of the first received message on the given
       topic(s). The topic of the received message is printed to stderr. This
       means that you can handle stdout and stderr separately.

       This can be helpful for scripting to get the current temperature
       reading and pipe it to somewhere else:

       `echo "The temperature is $(mqttui read-one room/temp)"`

       The output is the exact payload in its binary form. This might be valid
       ASCII / Unicode but could also be something not intended to be
       displayed on a terminal. For a human readable format use `--pretty` or
       `mqttui log`.

OPTIONS
       -r, --ignore-retained
              Do not return on a retained message on connection, wait for
              another message to arrive.

              Will be removed in the future in favor of `--only=live`.

       --only <ONLY>
              Only return a specific kind of message, either explicitly a
              retained one or one that is a current one, not stored on the
              broker.

              Keep in mind that when requesting only a retained message and
              there is none, this will only get noticed when the first
              non-retained message arrives. So this might take a while. When
              there is no retained message the process exits with the exit
              code 1.

              Possible values:

                     o retained

                     o live

       -p, --pretty
              Parse the payload and print it in a human readable pretty form.

              This might not be useful for piping the data.

       --qos <LEVEL> [default: 2]
              Maximum Quality of Service (`QoS`) for subscriptions and
              publishing.

              The lower Quality of Service level for publisher and subscriber
              is delivered from broker to subscriber. So subscribing with 0
              will never receive a 1 or 2. Publishing with 2 will be received
              as 1 when subscribed with 1.

              - 0: at most once (fire and forget)

              - 1: at least once (acknowledged delivery with potential
              duplicates)

              - 2: exactly once (assured delivery without duplicates)
              May also be specified with the MQTTUI_QOS environment variable.

       -h, --help
              Print help (see a summary with '-h')

       [TOPIC] [default: #]
              Topics to watch
              May also be specified with the MQTTUI_TOPIC environment
              variable.

MQTT CONNECTION
       -b, --broker <URL> [default: mqtt://localhost]
              URL which represents how to connect to the MQTT broker.

              Examples: `mqtt://localhost` `mqtt://localhost:1883`
              `mqtts://localhost` `mqtts://localhost:8883`
              `ws://localhost/path` `ws://localhost:9001/path`
              `wss://localhost/path` `wss://localhost:9001/path`
              May also be specified with the MQTTUI_BROKER environment
              variable.

       -u, --username <STRING>
              Username to access the mqtt broker.

              Anonymous access when not supplied.
              May also be specified with the MQTTUI_USERNAME environment
              variable.

       --password <STRING>
              Password to access the mqtt broker.

              Consider using a connection with TLS to the broker. Otherwise
              the password will be transported in plaintext.

              Passing the password via command line is insecure as the
              password can be read from the history! You should pass it via
              environment variable.
              May also be specified with the MQTTUI_PASSWORD environment
              variable.

       -i, --client-id <STRING>
              Specify the client id to connect with
              May also be specified with the MQTTUI_CLIENTID environment
              variable.

       --ca-cert <FILEPATH>
              Path to a trusted CA certificate PEM file for verifying the
              broker.

              The CA certificate has to be a X.509 v3 certificate since rustls
              does not support the less secure v1 certificates. See:
              <https://github.com/rustls/rustls/issues/2364>
              May also be specified with the MQTTUI_CA_CERTIFICATE environment
              variable.

       --client-cert <FILEPATH>
              Path to the TLS client certificate file.

              Used together with --client-private-key to enable TLS client
              authentication. The file has to be a DER-encoded X.509
              certificate serialized to PEM.
              May also be specified with the MQTTUI_CLIENT_CERTIFICATE
              environment variable.

       --client-private-key <FILEPATH>
              Path to the TLS client private key file.

              Used together with --client-cert to enable TLS client
              authentication. The file has to be a DER-encoded ASN.1 file in
              PKCS#8 form serialized to PEM.
              May also be specified with the MQTTUI_CLIENT_PRIVATE_KEY
              environment variable.

       --insecure
              Allow insecure TLS connections

                                   read-one                 mqttui-read-one(1)