Understanding ROS Topics
This tutorial introduces ROS topics as well as using the
rostopic commandline tools.
Before we move forward, let's start by making sure that we have roscore running, in a new terminal:
$ roscore If you left roscore running from the last tutorial, you may get the error message: roscore cannot run as another roscore/master is already running. Please kill other roscore/master processes before relaunching This is fine. Only one roscore needs to be running.
rostopic tool allows you to get information about ROS topics.
You can use the help option to get the available sub-commands for
root@erlerobot:~# rostopic -h rostopic is a command-line tool for printing information about ROS Topics. Commands: rostopic bw display bandwidth used by topic rostopic echo print messages to screen rostopic find find topics by type rostopic hz display publishing rate of topic rostopic info print information about active topic rostopic list list active topics rostopic pub publish data to topic rostopic type print topic type Type rostopic <command> -h for more detailed usage, e.g. 'rostopic echo -h'