getopts is a command of sh/bash

getopts_test.sh

#!/bin/bash -x

while getopts d opt; do
    case $opt in
        d) DEBUG="y" ;;
    esac
done

if [ -z $DEBUG ]; then
    echo "NO DEBUG"
else
    echo "DEBUG"
fi

# it could get another arguments
shift $((OPTIND - 1))
echo ${1}