Dummy script to parse arguments using `shift` bash built-in

parse.sh

#!/bin/bash

function usage {
    cat <<EOF
Usage: $0 [-dv] <path>
EOF
    exit 1
}

verbose=0
debug=0

function parse_option {
    local options="${1:1}"
    while (( "${#options}" )); do
        local option=${options:0:1}
        case $option in
        d)
            echo "Debug mode activated"
            debug=1;;
        v)
            let verbose="$verbose + 1"
            echo "Verbose mode increased";;
        esac
        options=${options:1}
    done
}

function parse_args {
    while (( "$#" )); do
        arg="$1"
        shift
        if [[ "${arg:0:1}" = "-" ]]; then
            parse_option "$arg"
            continue
        fi

        [ -e "$arg" -o -d "$arg" ] || usage

        path="$arg"
        echo "[DEBUG] 'path' is '$path'"

    done
    [ -z "$path" ] && usage
}

parse_args $@

echo verbose is $verbose