Defining Commands

The Command Interface

The Command interface is the core abstraction. Each command provides:

• name() — the primary command name
• aliases() — alternative names
• description() — one-line description for help listings
• describe(args) — detailed description for widgets
• execute(session, args) — the execution logic
• completers() — tab completion support

Using AbstractCommand

AbstractCommand is a convenient base class:

public class MyCommand extends AbstractCommand {
    public MyCommand() {
        super("mycommand", "mc", "my");  // name + aliases
    }

    @Override
    public String description() {
        return "Does something useful";
    }

    @Override
    public Object execute(CommandSession session, String[] args) {
        // Command logic here
        return null;
    }
}

Command Groups

SimpleCommandGroup organizes commands:

CommandGroup tools = new SimpleCommandGroup("tools",
    new UpperCommand(),
    new LowerCommand(),
    new CountCommand()
);

CommandSession

The CommandSession provides the execution context:

• session.terminal() — the terminal
• session.in() — input stream
• session.out() — output print stream
• session.err() — error print stream
• session.get(name) / session.put(name, value) — session variables
• session.workingDirectory() — current working directory
• session.lastExitCode() — last command's exit code