spectre.console/examples/Cli/Demo/Program.cs

using Demo.Commands;
using Demo.Commands.Add;
using Demo.Commands.Run;
using Demo.Commands.Serve;
using Spectre.Console.Cli;

namespace Demo;

public static class Program
{
    public static int Main(string[] args)
    {
        var app = new CommandApp();
        app.Configure(config =>
        {
            config.SetApplicationName("fake-dotnet");
            config.ValidateExamples();
            config.AddExample("run", "--no-build");

            // Run
            config.AddCommand<RunCommand>("run");

            // Add
            config.AddBranch<AddSettings>("add", add =>
            {
                add.SetDescription("Add a package or reference to a .NET project");
                add.AddCommand<AddPackageCommand>("package");
                add.AddCommand<AddReferenceCommand>("reference");
            });

            // Serve
            config.AddCommand<ServeCommand>("serve")
                .WithExample("serve", "-o", "firefox")
                .WithExample("serve", "--port", "80", "-o", "firefox");
            });

        return app.Run(args);
    }
}