18. Turtlesim Comms: Get Topic Info

Get Information About a Specific Topic

If we wish to get information about a specific topic, who is publishing to it, subscribed to it, or the type of message associated with it, we can use the command $rostopic info.
Let’s check into the /turtle1/cmd_vel topic:

As would be expected, there are two nodes registered on this topic. Our publisher, the teleop_turtle node, and our subscriber, the turtlesim node. Additionally, we can see that the type of message used on this topic is geometry_msgs/Twist .