Sample to show how to use getopt

cla_script.sh

#!/bin/bash

# 'arg-x' and 'x' behave like flags
# 'arg-y' and 'y' have required arguments.
# 'arg-z' and 'z' have optional arguments

# Initial value for the flag parameter (default false)
X=0

# create the option string
OPT_STR=`getopt -o xy:z:: --long arg-x,arg-y:,arg-z:: -n 'cla_script.sh' -- "$@"`
eval set -- "$OPT_STR"

# assign options to variables
while true ; do
    case "$1" in
        -x|--arg-x) X=1 ; shift ;; # The flag type
        -y|--arg-y)
            case "$2" in
                "") shift 2 ;;
                *) Y=$2 ; shift 2 ;;
            esac ;; # The one with required arguments
        -z|--arg-z)
            case "$2" in
                "") Z='default value' ; shift 2 ;;
                *) Z=$2 ; shift 2 ;; 
            esac ;; # The one with optional arguments
        --) shift ; break ;;
        *) echo "Check Usage !" ; exit 1 ;;
    esac
done

# Using the variables
echo "X is $X , Y is $Y and Z is $Z"

# $ sh cla_script.sh -x --arg-y='testing' -z
#=>  X is 1 , Y is testing and Z is default value
# $ sh cla_script.sh -y 'testing' --arg-z='testing this too'
#=>  X is 0 , Y is testing and Z is testing this too