ROS2-Usage.md

+# Nodes:
+
+### Run nodes:
+ros2 run <package_name> <executable_name>
+
+### Show all running nodes:
+ros2 node list
+
+### Access node information (and action info):
+ros2 node info <node_name>
+
+
+# Topics:
+
+### Visualize nodes and topics:
+rqt_graph
+
+### Show all active topics (and their type):
+ros2 topic list -t
+
+### Show data that is being published on a topic:
+ros2 topic echo <topic_name>
+
+### Access topic information:
+ros2 topic info <topic_name>
+
+### Show node's structure:
+ros2 interface show <msg type>
+
+### Publish data to a topic directly (arguments in YAML):
+ros2 topic pub <topic_name> <msg_type> '<args>'
+
+(options e.g.: --once/ --rate 1)
+
+### View rate at which data is being published:
+ros2 topic hz <topic_name>
+
+
+# Services:
+
+### Show all active services (and their typie):
+ros2 service list -t
+
+### Find all the services of a specific type:
+ros2 service find <type_name>
+
+### Show service's structure:
+ros2 interface show <type_name>
+
+### Call a service (arguments in YAML):
+ros2 service call <service_name> <service_type> <arguments>
+
+
+# Parameters:
+
+### Show parameters belonging to node:
+ros2 param list
+
+### Display the type and current value of a parameter
+ros2 param get <node_name> <parameter_name>
+
+### Change parameter's value at runtime:
+ros2 param set <node_name> <parameter_name> <value>
+
+### Save parameter configuration:
+ros2 param dump <node_name> > <node_name>.yaml
+
+### View all of node's current parameter values:
+ros2 param dump <node_name>
+
+### Load parameters from a file to an active node:
+ros2 param load <node_name> <parameter_file>
+
+### Start node using saved parameter values:
+ros2 run <package_name> <executable_name> --ros-args --params-file <file_name>
+
+# Actions:
+
+### Show all actions (and their type):
+ros2 action list -t
+
+### Introspect action:
+ros2 action info <action_name>
+
+### Send action goal (values in YAML):
+ros2 action send_goal <action_name> <action_type> <values>
+
+# Recording and running back data:
+
+### Make directory "bag_files" to store saved recordings:
+mkdir bag_files
+cd bag_files
+
+### Record data that is being published to a topic:
+ros2 bag record <topic_name>
+
+### Record multiple topics (and change name of file ros2 bag saves to):
+ros2 bag record -o <bag_file_name> <topic1_name> <topic2_name>
+
+### Show recording details:
+ros2 bag info <bag_file_name>
+
+### Replay the bag_file:
+ros2 bag play <bag_file_name>