# List all .msg, .srv, and .action types available
 $ ros2 interface list
 Messages:
     # Message types listed here
 Services:
     # Service types listed here
 Actions:
     # Action types listed here

 # Only list .msg types
 $ ros2 interface list --only-msg
 Messages:
     # Message types listed here

 # List all packages that generate messages, services, or actions
 $ ros2 interface packages
 action_msgs
 builtin_interfaces
 diagnostic_msgs
 # etc ...

 # Only list packages that generate actions
 $ ros2 interface packages --only-actions
 action_msgs
 example_interfaces
 test_msgs
 # etc ...
 
 # Show an interface definition
 $ ros2 interface show example_interfaces/Fibonacci
 Action:
     # Goal
     int32 order
     ---
     # Result
     int32[] sequence
     ---
     # Feedback
     int32[] sequence
 
 # In case of ambiguity (e.g. message and service with same name), show both
 $ ros2 interface show test_msgs/Primitives
 Message:
     bool bool_value
     byte byte_value
     char char_value
     # etc ...
 Service:
     bool bool_value
     byte byte_value
     char char_value
     # etc ...
     ---
     bool bool_value
     byte byte_value
     char char_value
     # etc ...