---

4 Services ¶

The service is obviously a very important concept of the Shepherd. On the Guile level, a service is represented as a record of type <service>. Each service has a number of properties that you specify when you create it: how to start it, how to stop it, whether to respawn it when it stops prematurely, and so on. At run time, each service has associated state: whether it is running or stopped, what PID or other value is associated with it, and so on.

This section explains how to define services and how to query their configuration and state using the Shepherd’s programming interfaces.

Note: The programming interface defined in this section may only be used within a shepherd process. Examples where you may use it include:

• the shepherd configuration file (see Service Examples);
• as an argument to herd eval root … (see The root Service);
• at the REPL (see Read-Eval-Print Loop Service).

These procedures may not be used in Guile processes other than shepherd itself.

• Defining Services
• Service Registry
• Interacting with Services
• Service De- and Constructors
• The root Service
• Legacy GOOPS Interface
• Service Examples
• Managing User Services