source: vendor/bash/3.1-p17/tests/getopts3.sub

aflag=
bflag=

while getopts ab: name -a -b 1 -a -a -a -b 5 -b 3 -a one two three four five
do
        case $name in
        a)      aflag=1 ;;
        b)      bflag=1
                bval=$OPTARG;;
        ?)      echo Usage: $0 [-a] [-b value] args
                exit 2;;
        esac

done

if [ ! -z "$aflag" ] ; then echo -a specified ; fi
if [ ! -z "$bflag" ] ; then echo -b $bval specified ; fi

set -- -a -b 1 -a -a -a -b 5 -b 3 -a one two three four five
if [ "$OPTIND" -gt 1 ]
then
        shift $(( $OPTIND - 1 ))
fi

echo remaining args: "$*"

exit 0