This is my standard boilerplate to add a help documentation to a bash script.

#!/bin/bash
###
### my-awesome-script — a meaningful description of the script
###
### Usage:
###   my-awesome-script [option]
###
### Options:
###   -d, --do-something      Do something
###   -h, --help              Show this help message and exit

help() {
    awk -F'### ' '/^###/ { print $2 }' "$0"
    exit
}

do_something() {
    echo "Doing something"
}

# Parse command line arguments
case "${1:-}" in
    -d|--do-something)
        do_something
        ;;
    -h|--help|"")
        help
        ;;
    *)
        echo "Error: Unknown option '$1'"
        help
        ;;
esac

Example output

$ my-awesome-script --help
my-awesome-script — a meaningful description of the script

Usage:
  my-awesome-script [option]

Options:
  -d, --do-something      Do something
  -h, --help              Show this help message and exit

What the help function does

The help() function extracts and displays help documentation that’s embedded directly in the script file itself. It uses awk to parse the script and find lines that contain help text.

Breaking down the awk command:

-F'### ': Sets the field separator to ###
/^###/: Matches lines that start with ###
{ print $2 }: Prints the second field (the help text)