Publish message from the command line

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I am trying to send a cmd_pos message using the command line. The type of the message is igntion::msgs::Double. I am using the command

ign topic -t "world/empty/model/simple-robot/joint/the_joint/cmd_pos" -p "1.3" --msgtype ignition::msgs::Double`

instead of "1.3", I also tried 1.3, data: 1.3, {data: 1.3}, and more. But I keep getting the message

Unable to create message of type[ignition::msgs::Double] with data[...]

with my value for p on the ....

How can I send a Double message using the command line?