Command Help

Console applications built with Spectre.Console.Cli include automatically generated help which is displayed when -h or --help has been specified on the command line.

The automatically generated help is derived from the configured commands and their command settings.

The help is also context aware and tailored depending on what has been specified on the command line before it. For example,

1. When -h or --help appears immediately after the application name (eg. application.exe --help), then the help displayed is a high-level summary of the application, including any command line examples and a listing of all possible commands the user can execute.

2. When -h or --help appears immediately after a command has been specified (eg. application.exe command --help), then the help displayed is specific to the command and includes information about command specific switches and any default values.

HelpProvider is the Spectre.Console class responsible for determining context and preparing the help text to write to the console. It is an implementation of the public interface IHelpProvider.

Styling the help text

Basic styling is applied to the generated help text by default, however this is configurable.

HelpProviderStyle is the Spectre.Console class that holds the style information for the help text.

The default theme shipped with Spectre.Console is provided by a factory method, HelpProviderStyle.Default.

However, you can explicitly set a custom theme when configuring a CommandApp, for example:

config.Settings.HelpProviderStyles = new HelpProviderStyle()
{
    Description = new DescriptionStyle()
    {
        Header = "bold",
    },
};

Removing all styling from help text is also possible, a good choice for ensuring maximum accessibility. This is configured by clearing the style provider entirely:

config.Settings.HelpProviderStyles = null;

See Markup for information about the use of markup in Spectre.Console, and Styles for a listing of supported styles.

Custom help providers

Whilst it shouldn't be common place to implement your own help provider, it is however possible.

You are able to implement your own IHelpProvider and configure a CommandApp to use that instead of the Spectre.Console help provider.

using Spectre.Console.Cli;

namespace Help;

public static class Program
{
    public static int Main(string[] args)
    {
        var app = new CommandApp<DefaultCommand>();

        app.Configure(config =>
        {
            // Register the custom help provider
            config.SetHelpProvider(new CustomHelpProvider(config.Settings));
        });

        return app.Run(args);
    }
}

There is a working example of a custom help provider demonstrating this.