# ROS 2 Skill — Examples Practical, copy-ready examples for every command group. All commands output JSON. Replace placeholder names (shown in ``) with values discovered from the live graph — never hardcode topic, node, service, action, or frame names. --- ## 1. Graph Exploration — Topics, Nodes, Services, Actions **Always start here to understand the live graph before acting.** ```bash # Detect ROS 2 version, distro, and domain ID python3 scripts/ros2_cli.py version # List all active topics with types python3 scripts/ros2_cli.py topics list # List all active nodes python3 scripts/ros2_cli.py nodes list # List all services with types python3 scripts/ros2_cli.py services list # List all action servers python3 scripts/ros2_cli.py actions list # Get details for a specific node (publishers, subscribers, services, actions) python3 scripts/ros2_cli.py nodes details # Get details for a specific topic (type, publishers, subscribers) python3 scripts/ros2_cli.py topics details # Find topics by message type python3 scripts/ros2_cli.py topics find geometry_msgs/msg/Twist python3 scripts/ros2_cli.py topics find geometry_msgs/msg/TwistStamped python3 scripts/ros2_cli.py topics find nav_msgs/msg/Odometry python3 scripts/ros2_cli.py topics find sensor_msgs/msg/LaserScan python3 scripts/ros2_cli.py topics find sensor_msgs/msg/CompressedImage python3 scripts/ros2_cli.py topics find sensor_msgs/msg/Image # Get a topic's message type python3 scripts/ros2_cli.py topics type # Find services by type python3 scripts/ros2_cli.py services find std_srvs/srv/Empty python3 scripts/ros2_cli.py services find std_srvs/srv/SetBool # Get a service's type python3 scripts/ros2_cli.py services type # Find actions by type python3 scripts/ros2_cli.py actions find turtlesim/action/RotateAbsolute python3 scripts/ros2_cli.py actions find nav2_msgs/action/NavigateToPose ``` --- ## 2. Interface Discovery **No live ROS 2 graph required** — reads from the ament resource index. ```bash # List all installed interface types (messages, services, actions) python3 scripts/ros2_cli.py interface list # Show field structure of a message, service, or action type python3 scripts/ros2_cli.py interface show geometry_msgs/msg/Twist python3 scripts/ros2_cli.py interface show std_srvs/srv/SetBool python3 scripts/ros2_cli.py interface show nav2_msgs/action/NavigateToPose # Get a default-value prototype (use as payload template) python3 scripts/ros2_cli.py interface proto geometry_msgs/msg/Twist python3 scripts/ros2_cli.py interface proto sensor_msgs/msg/JointState python3 scripts/ros2_cli.py interface proto std_srvs/srv/SetBool # List all packages that define interfaces python3 scripts/ros2_cli.py interface packages # List all interfaces defined by a specific package python3 scripts/ros2_cli.py interface package geometry_msgs python3 scripts/ros2_cli.py interface package std_msgs ``` --- ## 3. Topic Monitoring & Data Capture ```bash # Subscribe and return first message python3 scripts/ros2_cli.py topics subscribe python3 scripts/ros2_cli.py topics echo # Collect messages for a duration python3 scripts/ros2_cli.py topics subscribe --duration 5 python3 scripts/ros2_cli.py topics subscribe --duration 10 --max-messages 50 # Measure publish rate python3 scripts/ros2_cli.py topics hz python3 scripts/ros2_cli.py topics hz --window 20 --timeout 15 # Measure bandwidth python3 scripts/ros2_cli.py topics bw python3 scripts/ros2_cli.py topics bw --window 20 # Measure end-to-end latency (requires header.stamp) python3 scripts/ros2_cli.py topics delay python3 scripts/ros2_cli.py topics delay --window 20 # Check QoS compatibility — run before publish-until if subscribe times out unexpectedly python3 scripts/ros2_cli.py topics qos-check python3 scripts/ros2_cli.py topics qos-check # Get message structure for a type python3 scripts/ros2_cli.py topics message geometry_msgs/msg/Twist python3 scripts/ros2_cli.py topics message nav_msgs/msg/Odometry # Capture an image from a camera topic (saved to .artifacts/) python3 scripts/ros2_cli.py topics capture-image \ --topic \ --output photo.jpg # Capture with explicit type python3 scripts/ros2_cli.py topics capture-image \ --topic \ --output photo.jpg \ --type compressed ``` If multiple camera topics are found, prefer the one matching the user's context (front/rear, color/depth, compressed/raw). --- ## 4. Topic Publishing ```bash # Single-shot publish python3 scripts/ros2_cli.py topics publish '{"data": true}' # Publish for a duration (preferred for velocity commands) python3 scripts/ros2_cli.py topics publish \ '{"linear":{"x":0.3,"y":0,"z":0},"angular":{"x":0,"y":0,"z":0}}' --duration 3 # Publish using TwistStamped (if topics type returns TwistStamped) python3 scripts/ros2_cli.py topics publish \ '{"header":{"stamp":{"sec":0},"frame_id":""},"twist":{"linear":{"x":0.3,"y":0,"z":0},"angular":{"x":0,"y":0,"z":0}}}' \ --duration 3 # Stop the robot (publish zero velocity) python3 scripts/ros2_cli.py topics publish \ '{"linear":{"x":0,"y":0,"z":0},"angular":{"x":0,"y":0,"z":0}}' ``` --- ## 5. Robot Motion (Closed-Loop) **Always discover topic names before moving. Never hardcode `/cmd_vel` or `/odom`.** ```bash # Step 1: Discover velocity topic python3 scripts/ros2_cli.py topics find geometry_msgs/msg/Twist python3 scripts/ros2_cli.py topics find geometry_msgs/msg/TwistStamped # → confirm exact type: python3 scripts/ros2_cli.py topics type # Step 2: Discover odometry topic and verify it is live python3 scripts/ros2_cli.py topics find nav_msgs/msg/Odometry python3 scripts/ros2_cli.py topics hz ``` ### Emergency stop ```bash python3 scripts/ros2_cli.py estop python3 scripts/ros2_cli.py estop --topic ``` ### Drive forward 1 m (closed-loop) ```bash python3 scripts/ros2_cli.py topics publish-until \ '{"linear":{"x":0.2,"y":0,"z":0},"angular":{"x":0,"y":0,"z":0}}' \ --monitor --field pose.pose.position.x --delta 1.0 --timeout 30 ``` ### Drive 2 m along a curved path (Euclidean distance in XY) ```bash python3 scripts/ros2_cli.py topics publish-until \ '{"linear":{"x":0.2,"y":0,"z":0},"angular":{"x":0,"y":0,"z":0.2}}' \ --monitor \ --field pose.pose.position.x pose.pose.position.y \ --euclidean --delta 2.0 --timeout 60 ``` ### Drive with auto-computed deceleration zone (smooth stop) ```bash python3 scripts/ros2_cli.py topics publish-until \ '{"linear":{"x":0.4,"y":0,"z":0},"angular":{"x":0,"y":0,"z":0}}' \ --monitor --field pose.pose.position.x --delta 5.0 --timeout 60 # Deceleration zone is auto-computed from velocity and node params. # To override: add --slow-last 0.5 --slow-factor 0.3 ``` ### Rotate 90° CCW / left (positive --rotate, positive angular.z) ```bash python3 scripts/ros2_cli.py topics publish-until \ '{"linear":{"x":0},"angular":{"z":0.5}}' \ --monitor --rotate 90 --degrees --timeout 30 ``` ### Rotate 90° CW / right (negative --rotate, negative angular.z) ```bash python3 scripts/ros2_cli.py topics publish-until \ '{"linear":{"x":0},"angular":{"z":-0.5}}' \ --monitor --rotate -90 --degrees --timeout 30 ``` ### Drive until a LiDAR range drops below 0.5 m ```bash python3 scripts/ros2_cli.py topics publish-until \ '{"linear":{"x":0.2,"y":0,"z":0},"angular":{"x":0,"y":0,"z":0}}' \ --monitor --field ranges.0 --below 0.5 --timeout 60 ``` ### Open-loop fallback (no odometry available) ```bash # Move forward for 3 seconds, then stop — no distance guarantee python3 scripts/ros2_cli.py topics publish-sequence \ '[{"linear":{"x":0.3,"y":0,"z":0},"angular":{"x":0,"y":0,"z":0}},{"linear":{"x":0,"y":0,"z":0},"angular":{"x":0,"y":0,"z":0}}]' \ '[3.0, 0.5]' ``` --- ## 6. Services ```bash # Discover available services and their request structure before calling python3 scripts/ros2_cli.py services list python3 scripts/ros2_cli.py services details # Basic service call python3 scripts/ros2_cli.py services call '{}' # Call with payload python3 scripts/ros2_cli.py services call '{"data": true}' # Call with explicit type override (when auto-detect fails) python3 scripts/ros2_cli.py services call \ '{"data": true}' --service-type std_srvs/srv/SetBool # Longer timeout for slow services python3 scripts/ros2_cli.py --timeout 30 --retries 3 services call '{}' # Listen to service events (requires introspection enabled on server/client) python3 scripts/ros2_cli.py services echo --timeout 30 python3 scripts/ros2_cli.py services echo --max-messages 2 ``` --- ## 7. Actions **Always discover action name and goal structure before sending a goal.** ```bash # List all action servers python3 scripts/ros2_cli.py actions list # Get goal/result/feedback structure python3 scripts/ros2_cli.py actions details # Get action type python3 scripts/ros2_cli.py actions type # Send a goal and wait for result python3 scripts/ros2_cli.py actions send '' # Send a goal and collect feedback during execution python3 scripts/ros2_cli.py actions send '' --feedback # Longer timeout for long-running actions python3 scripts/ros2_cli.py actions send '' \ --feedback --timeout 120 # Cancel all in-flight goals on an action server python3 scripts/ros2_cli.py actions cancel # Echo live feedback from an action server (while goal is running) python3 scripts/ros2_cli.py actions echo python3 scripts/ros2_cli.py actions echo --duration 10 python3 scripts/ros2_cli.py actions echo --duration 30 --max-messages 20 ``` --- ## 8. Parameters **Always discover the node name and parameter names before reading or writing.** ```bash # List all parameters for a node python3 scripts/ros2_cli.py params list # Get a single parameter value python3 scripts/ros2_cli.py params get : python3 scripts/ros2_cli.py params get # Describe a parameter (type, description, constraints, read-only) python3 scripts/ros2_cli.py params describe : # Set a parameter (always describe first to confirm type and read-only status) python3 scripts/ros2_cli.py params set : python3 scripts/ros2_cli.py params set # Dump all parameters from a node python3 scripts/ros2_cli.py params dump # Bulk-load parameters from a JSON string python3 scripts/ros2_cli.py params load '{"param_a": 1.5, "param_b": true}' # Bulk-load parameters from a JSON file python3 scripts/ros2_cli.py params load /path/to/params.json # Search all nodes for parameters matching a pattern python3 scripts/ros2_cli.py params find vel python3 scripts/ros2_cli.py params find limit --node python3 scripts/ros2_cli.py params find all # Delete a parameter (node must allow undeclaring) python3 scripts/ros2_cli.py params delete python3 scripts/ros2_cli.py params delete param_a param_b param_c # Save current parameters as a named preset python3 scripts/ros2_cli.py params preset-save my_preset # Restore a preset onto a node python3 scripts/ros2_cli.py params preset-load my_preset # List all saved presets python3 scripts/ros2_cli.py params preset-list # Delete a preset python3 scripts/ros2_cli.py params preset-delete my_preset ``` --- ## 9. Lifecycle Management ```bash # List all managed (lifecycle) nodes in the graph python3 scripts/ros2_cli.py lifecycle nodes # List available states and transitions for a node python3 scripts/ros2_cli.py lifecycle list # List transitions for all managed nodes python3 scripts/ros2_cli.py lifecycle list # Get current state of a node python3 scripts/ros2_cli.py lifecycle get # Trigger a state transition by label (preferred) python3 scripts/ros2_cli.py lifecycle set configure python3 scripts/ros2_cli.py lifecycle set activate python3 scripts/ros2_cli.py lifecycle set deactivate python3 scripts/ros2_cli.py lifecycle set cleanup python3 scripts/ros2_cli.py lifecycle set shutdown # Trigger a transition by numeric ID python3 scripts/ros2_cli.py lifecycle set 1 # configure python3 scripts/ros2_cli.py lifecycle set 3 # activate python3 scripts/ros2_cli.py lifecycle set 4 # deactivate ``` Standard lifecycle sequence: `configure` → `activate` → (running) → `deactivate` → `cleanup` → `configure` again or `shutdown`. --- ## 10. Hardware & Controllers (ros2_control) **Always list controllers and verify hardware component state before any controller operation.** ```bash # List all loaded controllers and their states python3 scripts/ros2_cli.py control list-controllers # List available controller plugin types python3 scripts/ros2_cli.py control list-controller-types # List hardware components and their lifecycle states python3 scripts/ros2_cli.py control list-hardware-components python3 scripts/ros2_cli.py control lhc # List hardware interfaces (command and state interfaces) python3 scripts/ros2_cli.py control list-hardware-interfaces python3 scripts/ros2_cli.py control lhi ``` ### Explicit load → configure → activate workflow ```bash # 1. Load controller plugin (brings it to unconfigured) python3 scripts/ros2_cli.py control load-controller # 2. Configure it (unconfigured → inactive); surfaces on_configure() errors python3 scripts/ros2_cli.py control configure-controller # 3. Activate (inactive → active) python3 scripts/ros2_cli.py control set-controller-state active ``` ### Atomic controller switch (deactivate one, activate another) ```bash python3 scripts/ros2_cli.py control switch-controllers \ --deactivate \ --activate \ --strictness STRICT ``` ### Other controller operations ```bash # Deactivate or unload a controller python3 scripts/ros2_cli.py control set-controller-state inactive python3 scripts/ros2_cli.py control unload-controller # Drive hardware component through lifecycle python3 scripts/ros2_cli.py control set-hardware-component-state active python3 scripts/ros2_cli.py control set-hardware-component-state inactive # Visualise controller chain as PDF python3 scripts/ros2_cli.py control view-controller-chains python3 scripts/ros2_cli.py control view-controller-chains --output my_diagram.pdf ``` --- ## 11. Transforms (TF2) **Always discover frame names — never hardcode `map`, `base_link`, `odom`, or any frame name.** ```bash # Show the full TF frame hierarchy as an ASCII tree python3 scripts/ros2_cli.py tf tree python3 scripts/ros2_cli.py tf tree --duration 3 # Validate TF tree for cycles and multi-parent frames python3 scripts/ros2_cli.py tf validate # List all available TF frames python3 scripts/ros2_cli.py tf list # Lookup transform between two frames (use names from tf list) python3 scripts/ros2_cli.py tf lookup # Echo transform repeatedly python3 scripts/ros2_cli.py tf echo --count 10 python3 scripts/ros2_cli.py tf echo --once # Monitor transform updates for a specific frame python3 scripts/ros2_cli.py tf monitor --count 5 # Publish a static transform (runs in tmux session) python3 scripts/ros2_cli.py tf static 0 0 0.1 0 0 0 base_link camera_link # Convert quaternion to Euler angles (radians / degrees) python3 scripts/ros2_cli.py tf euler-from-quaternion 0 0 0.7071 0.7071 python3 scripts/ros2_cli.py tf euler-from-quaternion-deg 0 0 0.7071 0.7071 # Convert Euler angles to quaternion (radians / degrees) python3 scripts/ros2_cli.py tf quaternion-from-euler 0 0 1.5708 python3 scripts/ros2_cli.py tf quaternion-from-euler-deg 0 0 90 # Transform a point or vector from source to target frame python3 scripts/ros2_cli.py tf transform-point 1.0 0.0 0.0 python3 scripts/ros2_cli.py tf transform-vector 1.0 0.0 0.0 ``` --- ## 12. Diagnostics & Battery ```bash # List all diagnostic topics (discovered by type, not name) python3 scripts/ros2_cli.py topics diag-list # Read latest diagnostics (one-shot, all discovered diagnostic topics) python3 scripts/ros2_cli.py topics diag # Read from a specific diagnostic topic python3 scripts/ros2_cli.py topics diag --topic # Collect diagnostics over time python3 scripts/ros2_cli.py topics diag --duration 10 --max-messages 5 # List all battery topics (discovered by type, not name) python3 scripts/ros2_cli.py topics battery-list # Read battery state (one-shot, all discovered battery topics) python3 scripts/ros2_cli.py topics battery # Read from a specific battery topic python3 scripts/ros2_cli.py topics battery --topic ``` --- ## 13. Launch Management ```bash # List running launch sessions python3 scripts/ros2_cli.py launch list # Search for launch files by keyword (no session needed) python3 scripts/ros2_cli.py launch list robot python3 scripts/ros2_cli.py launch list nav2 python3 scripts/ros2_cli.py launch list camera # Launch a package in a tmux session python3 scripts/ros2_cli.py launch new # Launch with arguments python3 scripts/ros2_cli.py launch new use_sim_time:=false # Kill a running session python3 scripts/ros2_cli.py launch kill # Restart a session (same command as original launch) python3 scripts/ros2_cli.py launch restart # Launch Foxglove bridge for visualisation python3 scripts/ros2_cli.py launch foxglove python3 scripts/ros2_cli.py launch foxglove 9000 ``` --- ## 14. Run Management ```bash # List running run sessions python3 scripts/ros2_cli.py run list # Run a ROS 2 executable in a tmux session python3 scripts/ros2_cli.py run new # Run with arguments python3 scripts/ros2_cli.py run new --ros-args -p speed:=1.0 # Run with inline parameters python3 scripts/ros2_cli.py run new --params "speed:=1.0,max_vel:=2.0" # Run with a saved preset python3 scripts/ros2_cli.py run new --presets indoor # Kill a running session python3 scripts/ros2_cli.py run kill # Restart a session (same command as original run) python3 scripts/ros2_cli.py run restart ``` --- ## 15. Package, Component & Bag Introspection **No live ROS 2 graph required** for all commands in this section. ```bash # List all installed ROS 2 packages python3 scripts/ros2_cli.py pkg list # Find a package's install prefix python3 scripts/ros2_cli.py pkg prefix # List all executables in a package python3 scripts/ros2_cli.py pkg executables # Read a package's manifest (package.xml) python3 scripts/ros2_cli.py pkg xml # List all registered composable node types python3 scripts/ros2_cli.py component types ``` ### Component containers ```bash # List all running containers and their loaded components component list # Load a composable node into a container component load /my_container demo_nodes_cpp demo_nodes_cpp::Talker # Load with overridden node name component load /my_container demo_nodes_cpp demo_nodes_cpp::Talker --node-name my_talker # Unload a component by its unique_id (from component list or component load output) component unload /my_container 1 ``` **Standalone** (start container + load in one command): ```bash python3 scripts/ros2_cli.py component standalone demo_nodes_cpp demo_nodes_cpp::Talker # → starts /standalone_talker container in tmux, loads Talker, returns session + unique_id python3 scripts/ros2_cli.py component standalone demo_nodes_cpp demo_nodes_cpp::Talker --container-type component_container_mt # → same but using the multi-threaded container python3 scripts/ros2_cli.py component kill comp_demo_nodes_cpp_standalone_talker # → stop the standalone container when done (use the session name from standalone output) ``` ```bash # Inspect bag metadata: duration, topics, message counts, storage format python3 scripts/ros2_cli.py bag info /path/to/my_bag python3 scripts/ros2_cli.py bag info /path/to/my_bag/metadata.yaml ``` --- ## 16. System Health & Connectivity ```bash # Check whether the ROS 2 daemon is running python3 scripts/ros2_cli.py daemon status # Start the daemon (idempotent — safe to call when already running) python3 scripts/ros2_cli.py daemon start # Stop the daemon python3 scripts/ros2_cli.py daemon stop # Run ROS 2 system health checks python3 scripts/ros2_cli.py doctor # Include warning details python3 scripts/ros2_cli.py doctor --include-warnings # Show report sections for failed checks only python3 scripts/ros2_cli.py doctor --report-failed # Check cross-host ROS 2 connectivity (multicast + topic round-trip) python3 scripts/ros2_cli.py doctor hello python3 scripts/ros2_cli.py doctor hello --timeout 5 # Send one UDP multicast datagram (network connectivity test) python3 scripts/ros2_cli.py multicast send # Listen for UDP multicast packets python3 scripts/ros2_cli.py multicast receive python3 scripts/ros2_cli.py multicast receive --timeout 10 ``` --- ## 17. Discord — Image Delivery **Always use `discord_tools.py` to send files and images. Never use any other Discord integration.** ```bash # Capture an image and send to Discord python3 scripts/ros2_cli.py topics capture-image \ --topic \ --output photo.jpg python3 scripts/discord_tools.py send-image \ --path .artifacts/photo.jpg \ --channel-id \ --config ~/.nanobot/config.json # Send and delete the file after sending python3 scripts/discord_tools.py send-image \ --path .artifacts/photo.jpg \ --channel-id \ --config ~/.nanobot/config.json \ --delete # Send a controller diagram to Discord python3 scripts/ros2_cli.py control view-controller-chains --output diagram.pdf python3 scripts/discord_tools.py send-image \ --path .artifacts/diagram.pdf \ --channel-id \ --config ~/.nanobot/config.json \ --delete ``` --- ## 18. Global Options These go **before** the command name and apply to all service/action calls. ```bash # Extend timeout for slow networks or overloaded systems python3 scripts/ros2_cli.py --timeout 30 params list # Retry on unreliable networks python3 scripts/ros2_cli.py --retries 3 lifecycle get # Combine: 10 s per attempt, 3 total attempts python3 scripts/ros2_cli.py --timeout 10 --retries 3 services call '{}' ```