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Help#

Help documentation is automatically generated for the application.

Tip

To change the application name in the usage section, see UsageAppName and UsageAppNameStyle

Default Template#

The default template is as follows

{description}

Usage: {application} [command] [options] [arguments]

Arguments:

  {name}  (Multiple) <TYPE> [default] 
  {description}
  {allowed-values}

Options:

  -{short} | --{long} (Multiple) <TYPE> [default] 
  {description}
  {allowed-values}

Options also available for subcommands:

  -{short} | --{long} (Multiple) <TYPE> [default] 
  {description}
  {allowed-values}

Commands:

  {name} {description}

{extended-help-text}

Use "{application} [command] --help" for more information about a command.

Segments that do not apply for a command are not included.

For example, the last line are only included when a command has subcommands and "Options also available for subcommands:" is only included when options defined in parent commands can be provided in subcommands.

Modify behavior via settings#

There are a few settings to alter the default behavior, accessed via AppSettings.Help

new AppSettings
{
    Help
    {
        PrintHelpOption = true,
        ExpandArgumentsInUsage = true,
        TextStyle = HelpTextStyle.Basic,
        UsageAppNameStyle = UsageAppNameStyle.Executable,
        UsageAppName = "GlobalToolName"
    }
}

PrintHelpOption#

PrintHelpOption will include the help option in the list of options for every command.

ExpandArgumentsInUsage#

When true, arguments are expanded in the usage section so the names of all arguments are shown.

Given the command: Add(int value1, int value2, int value3 = 0)

Usage is Add [arguments]

When ExpandArgumentsInUsage = true

Usage is Add <value1> <value2> [<value3>]

TextStyle#

Default is HelpTextStyle.Detailed. HelpTextStyle.Basic changes the argument and option template to just {name} {description}

UsageAppNameStyle#

This determines what is used for {application} in Usage: {application}.

When Executable, the name will be Usage: {filename}.

When DotNet, the name will be Usage: dotnet {filename}

When Adaptive, if the file name ends with ".exe", then uses Executable else DotNet.

Adaptive & Executable will also detect when the app is a self-contained executable and use the executable filename.

UsageAppName#

When specified, this value will be used {application} in Usage: {application}. UsageAppNameStyle will be ignored.

Template variables#

The CommandAttribute supports the use of template variables to be used in help. %AppName% will be replaced with application name as determined above.

See docs for Commands > Template variables for details.

Custom Help Provider#

The template is driven by the HelpTextProvider class.

There are two options for overriding the behavior.

The first and simplest option is to inherit from HelpTextProvider and override the method for the section to modify.

The second option is to implement a new IHelpProvider.

Configure the provider with: appRunner.Configure(b => b.CustomHelpProvider = new MyHelpProvider());

Printing Help#

There are two ways to print help, and both require an instance of CommandContext.

ShowHelpOnExit#

Set CommandContext.ShowHelpOnExit = true to let the middleware print the help. This will be the last output for the context.

Help will not print if an exceptions the middleware.

PrintHelp()#

The ctx.PrintHelp() extension method, available using CommandDotNet.Help namespace, will print help for the target command.

If a target command was not determined, then help will print for the root command.