Inspecting the system

When our system is running, we might have several nodes and many more topics publishing messages amongst each other. We might also have nodes providing actions or services. For large systems, it is important to have tools that let us see what is running at a given time. ROS provides basic but very powerful tools with this goal in mind, from the CLI to GUI applications.

Listing nodes, topics, services, and parameters from our perspective, we should start with the most basic level of introspection. We are going to see how to obtain the list of nodes running and topics and services available at a given time:

Obtain the list of all

Command

Nodes running

rosnode list

Topics of all nodes running

rostopic ...

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