bash_option_parsing

#!/bin/bash

## Options Parsing ##
function parseOptions(){
  invalidOptionFlag=0 # set invalid option boolean
  options=($@)        # put the options into an array

  while [ ${#options[@]} -gt 0 ]; do    # while there are options to parse
    case ${options} in                  # Examin the current option
      (--*)                             # If it is a long option
        case ${options} in              # Parse the long option
          (--outfile)
            options=(${options[@]#${options}})

            if [ "${options:0:1}" == "-" ]; then
              continue
            else
              outFile="${options}"
              options=(${options[@]#${options}})
              continue
            fi
            ;;
          (*)
            echo "invalid option ${options}"
            invalidOptionFlag=1
            ;;
        esac
        ;;
      (-*)                             # If it is a short option
        if [ ${#options} -lt 3 ]; then # If it is a single short option
          case ${options} in
            (-y)
              testFlag=1
              ;;
            (*)
              echo "invalid option ${options}"
              invalidOptionFlag=1
              ;;
          esac
        else                           # Create single short options from combined short option
          multiOption="${options}"
          first="-${multiOption:1:1}"
          remaining="-${multiOption:2}"
          options=(${options[@]#${options}} $first $remaining)
          continue
        fi
        ;; 
    esac

    options=(${options[@]#${options}}) # Remove the parsed option from options array
  done

  return $invalidOptionFlag
}

## Set variables ##
testFlag=0
outFile=''

## Parse options ##
parseOptions $@

## Main ##
if [ $? == 0 ]; then
  echo "testFlag = $testFlag"
  echo "outFile = $outFile"
fi