Launch Your Talker and Listener Together

Create a launch directory inside the ROS package:

cd ~/ros2_ws/src/robotnix_pubsub
mkdir -p launch

Create:

launch/student_system.launch.py

using the launch description from the previous lesson.

Run directly while developing

The pinned launch tutorial demonstrates that a launch file can be run directly by path/from its directory.

From the launch directory, with Jazzy and your overlay sourced:

ros2 launch student_system.launch.py

You should see launch messages showing processes starting, followed by your node log output.

Inspect from another terminal

ros2 node list
ros2 topic list -t
ros2 topic info /student_chatter --verbose

The graph should match the two-node system you previously started manually.

Stop the system

Use Ctrl+C in the launch terminal.

Observe shutdown messages. Launch is managing more than a static configuration file; it is supervising the processes it started.

Checkpoint

Compare manual startup and launch startup: