Simple template for shell scripts

help-template.sh

#!/bin/bash
# help-template.sh
#
# Simple template for shell scripts
#
Help=$(cat <<-"HELP"
my-script — does one thing well

Usage:
  my-script <input> <output>

Options:
  <input>   Input file to read.
  <output>  Output file to write. Use '-' for stdout.
  -h        Show this message.
HELP
)

help() {
  echo "$Help"
}

if [[ $# == 0 ]] || [[ "$1" == "-h" ]]; then
  help
  exit 1
fi

echo "Hello World"