Catch and processing script arguments

catch-arguments.sh

# Function to print help message and exit
usage () {
  [ ! -z "$1" ] && printf "\n \e[31m[ error ]\e[0m $0: %s\n" "$1" >&2
  printf "$USAGE" >&2
  exit 2
}

# Catch arguments
for (( i=1; i<=$#; i++ )); do
  case "${!i}" in
    -*  ) VAL=$((i+1))
          [[ -n "${!VAL}" && "${!VAL}" != "-"* ]] && VAL="${!VAL}" || VAL=true
          case "${!i}" in
            --arg1|-a1  ) [ "$VAL" != true ] && ARG1="$VAL";;
            --arg2|-a2  ) [ "$VAL" != true ] && ARG2="$VAL";;
            --help|-h   ) usage;;
            *           ) usage "unknown argument ${!i}";;
          esac;;
    *   ) continue;;
  esac
done