help-use-a-function-and-here-document

Help: use a function and HERE document

Provide help using a function and HERE document syntax such as:

help(){
cat << HERE
This is my script.

This is a good place for an explanation of the syntax,
and examples, and explanations of any options, etc.
HERE
}

To show the help, one way is like this:

if [ "$#" -ge 1 ]; then
    case "$1" in
        -h|--help)
            help; exit 0
            ;;
    esac
fi

Markdown

We prefer help text to use markdown formatting.

Examples:

• For code, indent 4 spaces.

• For options, use a bullet list: indent 2 spaces and use an asterisk, and use a blank line between each list item.

• For a section headline, start a line with two hash signs "##".

Syntax and example

If a script is a typical command, then we prefer to show the syntax and an example like this:

Syntax:

    foo <text> [...]

Example:

    $ foo hello

    $ foo hello world

Note:

• We prefer using a "$" dollar sign to indicate a typical command line prompt.

Options

If a script has command line options, then we prefer to show them using a bullet list, like this:

Options:

    * -h --help: 
    show this help information

    * -v --version: 
    show the command name, version number, and updated date.

Tracking

If a script is intended for the public, then we prefer to show tracking metadata using a bullet list, like this:

Tracking:

    * Command: my-foo-script
    * Version: 1.0.0
    * Updated: 2018-01-01
    * License: GPL
    * Website: https://example.com/example/
    * Contact: Alice Adams (alice@example.com)

Tracking varaibles

If a script is intended for the public, and we want it to be professional, then we prefer to set tracking variables and print the variables in the help, like this:

program_command="my-foo-script"
program_version="1.0.0"
program_created="2016-01-01"
program_updated="2016-01-11"
program_license="GPL-2.0 or GPL-3.0"
program_website="https://example.com"
program_contact="Alice Adams (alice@example.com)"

help(){
cat << EOF
...

## Tracking

    * Command: $program_command
    * Version: $program_version
    * Created: $program_created
    * Updated: $program_updated
    * License: $program_license
    * Website: $program_website
    * Contact: $program_contact

EOF
}

To show the help, we parse the command line options; one way is this simple code:

if [ "$#" -ge 1 ]; then
    case "$1" in
        -h|--help)
            help; exit 0
            ;;
        -v|--version)
            out "$program_version"; exit 0
            ;;
        --program-command)
            out "$program_command"; exit 0
            ;;
        --program-version)
            out "$program_version"; exit 0
            ;;
        --program-updated)
            out "$program_version"; exit 0
            ;;
        --program-license)
            out "$program_license"; exit 0
            ;;
        --program-website)
            out "$program_website"; exit 0
            ;;
        --program-contact)
            out "$program_contact"; exit 0
            ;;
    esac
fi