getopts

#!/usr/bin/env bash

#while getopts a:b name; do
#    echo name: "$name", OPTARG: "$OPTARG", OPTIND: $OPTIND, OPTERR: "$OPTERR"
#done

echo "$*"
echo "$@"

status=off
filename=
output=

usage() {
    echo Usage:
    echo "$0 [-h] [-v] [-f <filename>] [-o <filename>]"
    exit 0
}

while getopts :hvf:o: name; do
    case "$name" in
    h)
        echo name: "$name", OPTARG: "$OPTARG", OPTIND: $OPTIND, OPTERR: "$OPTERR"
        usage
        ;;
    v)
        echo name: "$name", OPTARG: "$OPTARG", OPTIND: $OPTIND, OPTERR: "$OPTERR"
        status=on
        ;;
    f)
        echo name: "$name", OPTARG: "$OPTARG", OPTIND: $OPTIND, OPTERR: "$OPTERR"
        filename="$OPTARG"
        if [ ! -f "$filename" ]; then
            echo filename: "$filename" does not exist
            exit 5
        fi
        ;;
    o)
        echo name: "$name", OPTARG: "$OPTARG", OPTIND: $OPTIND, OPTERR: "$OPTERR"
        output="$OPTARG"
        if [ ! -f "$output" ]; then
            echo output: "$output" does not exist
            exit 5
        fi
        ;;
    '?')  # ? have to be quoted, because it's a wildcard, or \?
        echo name: "$name", OPTARG: "$OPTARG", OPTIND: $OPTIND, OPTERR: "$OPTERR"
        echo invalid option -"$OPTARG"
        exit 6
        ;;
    :)
        echo name: "$name", OPTARG: "$OPTARG", OPTIND: $OPTIND, OPTERR: "$OPTERR"
        echo option -"$OPTARG" require a argument
        exit 7
        ;;
    esac
done

echo status: $status, filename: "$filename", output: "$output",