Bash option parsing example without using getopt and using globals instead of a hash

parseCli.sh

# Avoids string-keyed arrays as not available in old bash on Macs. Supports:
# * arguments and values with spaces if quoted.
# * arguments embedded in options (e.g. "commands").
# * arguments that look like option (start with a -) after a lone "--"
# * options with values, without values, and with optional values.
# * repeated options with values and counted flags.
# * both "key=value"" and "key value" style options
function parseCli() {
   # globals
   OPT_DOWNLOAD=0
   OPT_MD5=0
   OPT_INSTALL=0
   OPT_REPORT=0
   OPT_REPORT_FILE="packages.txt"
   OPT_CACHE_DIR=""    # Flag value for do not cache is ""
   OPT_VERBOSE=0       # Counted flag
   OPT_FORCE=0         # Counted flag
   OPT_MANIFEST=()
   OPT_ARGS=()
   
   # Parameter list must be manually reduced on each loop using shift.
   while [[ $# -gt 0 ]]; do
      case "$1" in
         # Flag
         -d|--download)
            OPT_DOWNLOAD=1
            shift
            ;;
         # Flag
         -c|--checksum|--md5)
            OPT_MD5=1
            shift
            ;;
         # Flag
         -i|--install)
            OPT_INSTALL=1
            shift
            ;;
         # Requires value if set
         --cacheDir|--cacheDir=*)
            if [[ $1 == *'='* ]]; then
               OPT_CACHE_DIR="${1#*=}"
               shift
            elif [[ -n "$2" ]] && [[ ${2:0:1} != "-" ]]; then
               OPT_CACHE_DIR="$2"
               shift 2
            else
               echo "Error: no directory specified for option --cacheDir." >&2
               exit 1
            fi
            ;;
         # Optional value (tracks if set, even to default)
         -r|--report|-r=*|--report=*)
            if [[ $1 == *'='* ]]; then
               OPT_REPORT=1
               # Don't change if --option= without value.
               [[ -n "${1#*=}" ]] && OPT_REPORT_FILE="${1#*=}"
               shift
            elif [[ -n "$2" ]] && [[ ${2:0:1} != "-" ]]; then
               OPT_REPORT=1
               OPT_REPORT_FILE="$2"
               shift 2
            else
               OPT_REPORT=1
               shift
            fi
            ;;
         # Repeated value
         -m|--manifest|-m=*|-manifest=*)
            if [[ $1 == *'='* ]]; then
               # Don't change if --option= without value.
               [[ -n "${1#*=}" ]] && OPT_MANIFEST+=("${1#*=}")
               shift
            elif [[ -n "$2" ]] && [[ ${2:0:1} != "-" ]]; then
               OPT_MANIFEST+=("$2")
               shift 2
            else
               echo "Error: no file specified for option -m | --manifest." >&2
               exit 1
            fi
            ;;
         # Counted flag
         -v|--verbose)
            (( OPT_VERBOSE+=1 ))
            shift
            ;;
         # Counted flag
         -q|--quiet)
            (( OPT_VERBOSE-=1 ))
            shift
            ;;
         # Counted flag
         -f|--force)
            (( OPT_FORCE+=1 ))
            shift
            ;;
         # Terminate parsing to allow arguments that look like options
         --)
            shift
            OPT_ARGS+=("$@")
            break
            ;;
         # Anything begining with - not already parsed is an error
         -*)
            echo "Error: Unknown option \"$1\"" >&2
            exit 1
            ;;
         # If not begining with "-", it is an option
         *)
            OPT_ARGS+=("$1")
            shift
            ;;
      esac
   done
   
   # Report option settings
   if [[ $OPT_VERBOSE -gt 1 ]]; then
      printf "Cli Parsing:\n"
      printf " OPT_DOWNLOAD=%s\n"     "$OPT_DOWNLOAD"
      printf " OPT_MD5=%s\n"          "$OPT_MD5"
      printf " OPT_INSTALL=%s\n"      "$OPT_INSTALL"
      printf " OPT_REPORT=%s\n"       "$OPT_REPORT"
      printf " OPT_REPORT_FILE=%s\n"  "$OPT_REPORT_FILE"
      printf " OPT_VERBOSE=%s\n"      "$OPT_VERBOSE"
      printf " OPT_MANIFEST=%s\n"     "${OPT_MANIFEST[@]}"
      printf " OPT_ARGS=%s\n"         "${OPT_ARGS[@]}"
      printf " OPT_CACHE_DIR=%s\n"    "$OPT_CACHE_DIR"
      printf " OPT_FORCE=%s\n"        "$OPT_FORCE"
   fi
}