bashCommandParser.sh

#!/bin/bash

#
# Sample code which implements a bash commandline parser
#
# Option format of flag:
# -x and -x- will mark a flag as false (0)
# -x+ will mark a flag as true (1)
#
# Option format of parameter:
# -x or --some_long_option_name_for_x
#
# (C) 2018 framp at linux-stips-and-tricks dot de
#

# 0 -> disable, 1 -> enable, -1 -> neither
function isEnableDisableParm() { # parm
case "$1" in
		-*-) echo 0;;
		-*+|-*) echo 1;;
		*) echo -1;;
	esac
}

PARAMS=""

while (( "$#" )); do
  case "$1" in
    -f|--flag-with-argument)
      FARG=$2
      shift 2
      echo "Got flag -f: $FARG"
      ;;
    -g|--gflag-with-argument)
      GARG=$2
      shift 2
      echo "Got flag -g: $GARG"
      ;;
    -e|-e[+-])
	  f="$1"
      shift 1
	  EARG=$(isEnableDisableParm "$f")
      if (( $EARG < 0 )); then
		echo "Invalid flag $f"
	  else
		echo "Got flag -e: $EARG"
	  fi
      ;;
    --) # end argument parsing
      shift
      break
      ;;
    -*|--*|+*|++*) # unsupported flags
      echo "Error: Unsupported flag $1" >&2
      exit 1
      ;;
    *) # preserve positional arguments
      [[ -z $PARAMS ]] && PARAMS="$1" || PARAMS="$PARAMS $1"
      shift
      ;;
  esac
done

# set positional arguments in argument list $@
set -- $PARAMS

i=1
while (( "$#" )); do
	echo "Positional parm $(( i++ )): $1"
	shift
done