Discover Services and Their Types

Start Turtlesim in a sourced terminal.

Then list services:

ros2 service list

You will see Turtlesim-specific services such as /clear, /reset, /spawn, and turtle-specific operations, along with parameter infrastructure services.

Show types

The official tutorial uses:

ros2 service list -t

You may see entries such as:

/clear [std_srvs/srv/Empty]
/spawn [turtlesim/srv/Spawn]

Ask about one service

ros2 service type /spawn

Then inspect endpoint counts:

ros2 service info /spawn

Find services by type

The source tutorial also demonstrates:

ros2 service find std_srvs/srv/Empty

This reverses the question. Instead of "what type is this service?" you ask "which services use this type?"

Checkpoint

Create:

Do not call them yet. First know what is available.