Linux bash argument parsing

example-param-parsing.sh

#!/bin/bash

# Author: Dominik Bartsch

usage="
Usage: $(basename "$0") [OPTIONS]
A tool to gather several infromation about the OpenShift projects/namespaces and capacity
Options:
    -h, --help                Show this help text
    -f, --foo                 Do the foo thing
    -b, --bar                 Do the bar thing
    -s, --summary <detail>    (Default Behavior) Shows the complete summary.
                                If detail is provided more details are shown.
"
function help () {
  echo "$usage"
}

invalid_option="Invalid Option $1"

function error () {
  echo
  echo "$invalid_option"
  help
}

# Transform long options to short ones
for arg in "$@"; do
  shift
  case "$arg" in
    "--help")
      set -- "$@" "-h" ;;
    "--foo")
      set -- "$@" "-f" ;;
    "--bar")
      set -- "$@" "-b" ;;
    "--summary")
      set -- "$@" "-s" ;;
    "--"*)
      error ${arg};
      exit 1
      ;;
    *)
      set -- "$@" "$arg"
  esac
done

while getopts ':h :f :b :s:' option
do
  case "$option" in
    h)
      echo "$usage"
      exit 0
      ;;
    f)
      echo "Doing foo..."
      foo_method
      exit 0
      ;;
    b)
      echo "Doing bar..."
      bar_method
      exit 0
      ;;
    s)
      if [ "$OPTARG" == "detail" ]
      then
        echo "A optional arg was provided..."
        detailed_summary_method
      else
        echo "No optional arg was provided..."
        no_detailed_summary_method
      fi
      summary
      exit 0
      ;;
   "?")
      error "$OPTARG"
      exit 1
      ;;
  esac
done
shift $((OPTIND - 1))