Documenting Scripts — Click Documentation (8.1.x)

# Documenting Scripts

Click makes it very easy to document your command line tools. First of all, it automatically generates help pages for you. While these are currently not customizable in terms of their layout, all of the text can be changed.

## Help Texts

Commands and options accept help arguments. In the case of commands, the docstring of the function is automatically used if provided.

Simple example:

    @click.command()
    @click.option('--count', default=1, help='number of greetings')
    @click.argument('name')
    def hello(count, name):
        """This script prints hello NAME COUNT times."""
        for x in range(count):
            click.echo(f"Hello {name}!")

And what it looks like:

    $ hello --help
    Usage: hello [OPTIONS] NAME

      This script prints hello NAME COUNT times.

    Options:
      --count INTEGER  number of greetings
      --help           Show this message and exit.

## Documenting Arguments

`click.argument()` does not take a `help` parameter. This is to follow the general convention of Unix tools of using arguments for only the most necessary things, and to document them in the command help text by referring to them by name.

You might prefer to reference the argument in the description:

    @click.command()
    @click.argument('filename')
    def touch(filename):
        """Print FILENAME."""
        click.echo(filename)

And what it looks like:

    $ touch --help
    Usage: touch [OPTIONS] FILENAME

      Print FILENAME.

    Options:
      --help  Show this message and exit.

Or you might prefer to explicitly provide a description of the argument:

    @click.command()
    @click.argument('filename')
    def touch(filename):
        """Print FILENAME.

        FILENAME is the name of the file to check.
        """
        click.echo(filename)

And what it looks like:

    $ touch --help
    Usage: touch [OPTIONS] FILENAME

      Print FILENAME.

      FILENAME is the name of the file to check.

    Options:
      --help  Show this message and exit.

For more examples, see the examples in Arguments.

## Preventing Rewrapping

The default behavior of Click is to rewrap text based on the width of the terminal, to a maximum 80 characters. In some circumstances, this can become a problem. The main issue is when showing code examples, where newlines are significant.

Rewrapping can be disabled on a per-paragraph basis by adding a line with solely the `\b` escape marker in it. This line will be removed from the help text and rewrapping will be disabled.

Example:

    @click.command()
    def cli():
        """First paragraph.

        This is a very long second paragraph and as you
        can see wrapped very early in the source text
        but will be rewrapped to the terminal width in
        the final output.

        \b
        This is
        a paragraph
        without rewrapping.

        And this is a paragraph
        that will be rewrapped again.
        """

And what it looks like:

    $ cli --help
    Usage: cli [OPTIONS]

      First paragraph.

      This is a very long second paragraph and as you can see wrapped very early in
      the source text but will be rewrapped to the terminal width in the final
      output.

      This is
      a paragraph
      without rewrapping.

      And this is a paragraph that will be rewrapped again.

    Options:
      --help  Show this message and exit.

To change the maximum width, pass `max_content_width` when calling the command.

    cli(max_content_width=120)

## Truncating Help Texts

Click gets command help text from function docstrings. However if you already use docstrings to document function arguments you may not want to see :param: and :return: lines in your help text.

You can use the `\f` escape marker to have Click truncate the help text after the marker.

Example:

    @click.command()
    @click.pass_context
    def cli(ctx):
        """First paragraph.

        This is a very long second
        paragraph and not correctly
        wrapped but it will be rewrapped.
        \f

        :param click.core.Context ctx: Click context.
        """

And what it looks like:

    $ cli --help
    Usage: cli [OPTIONS]

      First paragraph.

      This is a very long second paragraph and not correctly wrapped but it will be
      rewrapped.

    Options:
      --help  Show this message and exit.

## Meta Variables

Options and parameters accept a `metavar` argument that can change the meta variable in the help page. The default version is the parameter name in uppercase with underscores, but can be annotated differently if desired. This can be customized at all levels:

    @click.command(options_metavar='<options>')
    @click.option('--count', default=1, help='number of greetings',
                  metavar='<int>')
    @click.argument('name', metavar='<name>')
    def hello(count, name):
        """This script prints hello <name> <int> times."""
        for x in range(count):
            click.echo(f"Hello {name}!")

Example:

    $ hello --help
    Usage: hello <options> <name>

      This script prints hello <name> <int> times.

    Options:
      --count <int>  number of greetings
      --help         Show this message and exit.

## Command Short Help

For commands, a short help snippet is generated. By default, it’s the first sentence of the help message of the command, unless it’s too long. This can also be overridden:

    @click.group()
    def cli():
        """A simple command line tool."""

    @cli.command('init', short_help='init the repo')
    def init():
        """Initializes the repository."""

    @cli.command('delete', short_help='delete the repo')
    def delete():
        """Deletes the repository."""

And what it looks like:

    $ repo.py
    Usage: repo.py [OPTIONS] COMMAND [ARGS]...

      A simple command line tool.

    Options:
      --help  Show this message and exit.

    Commands:
      delete  delete the repo
      init    init the repo

## Command Epilog Help

The help epilog is like the help string but it’s printed at the end of the help page after everything else. Useful for showing example command usages or referencing additional help resources.

    @click.command(epilog='Check out our docs at https://click.palletsprojects.com/ for more details')
    def init():
        """Initializes the repository."""

And what it looks like:

    $ repo.py --help
    Usage: repo.py [OPTIONS]

      Initializes the repository.

    Options:
      --help  Show this message and exit.

      Check out our docs at https://click.palletsprojects.com/ for more details

## Help Parameter Customization

Changelog

Added in version 2.0.

The help parameter is implemented in Click in a very special manner. Unlike regular parameters it’s automatically added by Click for any command and it performs automatic conflict resolution. By default it’s called `--help`, but this can be changed. If a command itself implements a parameter with the same name, the default help parameter stops accepting it. There is a context setting that can be used to override the names of the help parameters called `help_option_names`.

This example changes the default parameters to `-h` and `--help` instead of just `--help`:

    CONTEXT_SETTINGS = dict(help_option_names=['-h', '--help'])

    @click.command(context_settings=CONTEXT_SETTINGS)
    def cli():
        pass

And what it looks like:

    $ cli -h
    Usage: cli [OPTIONS]

    Options:
      -h, --help  Show this message and exit.