CODE EXAMPLE FOR SHELL

getopts without argument

#!/bin/bash

while getopts ":a:b:cd" options; do 
# Option -a -b need arguments / -c -d doesn't need argument to work
    case "${options}" in
  		a)
          VARA=${OPTARG}
        ;;
		b)
          VARB=${OPTARG}
        ;;
		c)
          echo "Option -c"
        ;;
		d)
          echo "Option -d"
        ;;
        :)                         # If expected argument omitted:
     	  echo "Error: -${OPTARG} requires an argument."
          exit 1                       
        ;;
        *)                         # If unknown (any other) option:
          echo "Error: unknown option"
          exit 1
        ;;
	esac
done