A snippet to showcase how to manipulate options and arguments in Bash

argtest.sh

#!/bin/bash
main()
{
	local opt_a=
	local opt_b=
	local opt_c=
	local args=
	getargs "$@"

	if [ -n "$opt_a" ]; then echo "opt_a [$opt_a]"; fi
	if [ -n "$opt_b" ]; then echo "opt_b [$opt_b]"; fi
	if [ -n "$opt_c" ]; then echo "opt_c [$opt_c]"; fi
	for arg in "${args[@]}"; do echo "arg [$arg]"; done
}

getargs()
{
	while getopts 'a:b:c:h' o; do
		case $o in
			a) opt_a=$OPTARG;;
			b) opt_b=$OPTARG;;
			c) opt_c=$OPTARG;;
			h) usage; exit 0;;
			*) usage; exit 1;;
		esac
	done
	shift $((OPTIND - 1))
	args=("$@")
}

usage()
{
	local cmd=${0##*/}
	cat <<EOF
Usage:
  $cmd [ OPTION [ OPTION ... ] ]

Option:
  -a ARG  parameter a
  -b ARG  parameter b
  -c ARG  parameter c
  -h      show this help message and exit

EOF
}

main "$@"