Displaying the help

Description

Help prints detailed information about how to use the CLI application or one of its commands.

How to display the help

From a user perspective, there are multiple ways to print the help to the console:

• by passing the --help option in the command, for example ./app print --help.
• if commands are used, by calling the help command, eventually followed by any command, for example ./app help print.
• when the command is invalid or incomplete, for example ./app print, assuming the print command has a required message option.
• when calling a non-leaf command, for example ./app plugin, assuming plugin is not a command in itself but a group of multi-level commands such as ./app plugin print -m 'hello'.

Use ./myapp --help to print the help usage of the overall application. The help option is automatically registered to the application as well as to every commands.

If at least one command is registered, use ./myapp help to print the usage of the application or myapp help <command...> to print the usage of specific commands.

For example, an application myapp which has a command secrets with a command set could print the usage of the group of multi-level command secrets set with the arguments ./myapp help secrets set.

In the end, using the help option of the "secrets set" command or using help command with "secret set" as arguments are equivalent and work by default:

# Option
./myapp secrets set --help
# Command
./myapp help secrets set

Integration

Using helping

For the developer, printing help uses a combination of the helping and help methods. The helping method takes the parsed data and check if printing help is requested. The help method return the usage information as string.

Here's how to display help with helping and help:

const args = params.parse();
const commands = params.helping(args);
if(commands){
  process.stdout.write(params.help(commands))
}

The output looks like:

NAME
  precious - Manage your precious

SYNOPSIS
  precious <command>

OPTIONS
  -h --help                 Display help information

COMMANDS
  secrets                   No description yet for the secrets command
  help                      Display help information

EXAMPLES
  precious --help           Show this message
  precious help             Show this message

With routing

Routing is enabled if the application or its command defined the route property which point to a function or a module name.

Here's how to display help with routing:

// Routing to help required `help.route` to be set
const shell = require('shell')
shell({
  handler: './some/module'
}).route(/*...optional user arguments...*/)

Invalid or incomplete command

TODO: describe how help could be printed when an error occurred.

Non-leaf command

TODO: describe how help could be printed for every non leaf command if requested.

Overwriting

It is possible to overwrite the default help options and commands such as to provide a personalised message:

const shell = require('shell')
shell = ({
{ options:
  { help: 
    { description: 'Overwrite description' } } }
)