Setup

roscore # making sure that we have roscore running
rosrun turtlesim turtlesim_node
rosrun turtlesim turtle_teleop_key # Now you can use the arrow keys of the keyboard to drive the turtle around.

ROS Topics

sudo apt-get install ros-kinetic-rqt
sudo apt-get install ros-kinetic-rqt-common-plugins
rosrun rqt_graph rqt_graph

rostopic -h
rostopic echo /turtle1/cmd_vel # you will now see topic datas when you press the arrow key in <tt class="backtick">turtle_teleop_key</tt> terminal

rostopic list -h # figure out what argument the list sub-command needs
rostopic list -v # displays a verbose list of topics to publish to and subscribe to and their type

rostopic type /turtle1/cmd_vel  # You should get the message type of the topic: geometry_msgs/Twist
rosmsg show geometry_msgs/Twist  #  look at the details of the message using rosmsg

Using rostopic pub

# publishes data on to a topic, rostopic pub [topic] [msg_type] [args]
rostopic pub - /turtle1/cmd_vel geometry_msgs/Twist -- '[2.0, 0.0, 0.0]' '[0.0, 0.0, 1.8]'
#  publishes the velocity commands at a rate of  Hz on the velocity topic
rostopic pub /turtle1/cmd_vel geometry_msgs/Twist -r  -- '[2.0, 0.0, 0.0]' '[0.0, 0.0, -1.8]'
# Now We can also look at what is happening in rqt_graph. 
# and see the data published by our turtlesim
rostopic echo /turtle1/pose<br /><br /># see how fast the <tt class="backtick">turtlesim_node</tt> is publishing <tt class="backtick">/turtle1/pose, $ rostopic hz [topic]<br /></tt>rostopic hz /turtle1/pose<br /><br /># get in depth information about a topic<br />rostopic type /turtle1/cmd_vel | rosmsg show

Using rqt_plot

rosrun rqt_plot rqt_plot
# a text box in the upper left corner gives you the ability to add any topic to the plot. 
# Typing /turtle1/pose/x and add it.
# Typing /turtle1/pose/y and add it.