TIL: bash flags

error()
{
    echo "$arg0: $*" >&2
    exit 1
}

flags()
{
    while test $# -gt 0
    do
        case "$1" in
        (-s|--source)
            shift
            [ $# = 0 ] && error "No source directory specified"
            export SOURCE="$1"
            shift;;
        (-d|--destination)
            shift
            [ $# = 0 ] && error "No destination specified"
            export DESTINATION="$1"
            shift;;
        (-c|--credentials)
            shift
            [ $# = 0 ] && error "No credentials specified"
            export CREDENTIALS="$1"
            shift;;
        (-b|--bandwidth)
            shift
            [ $# = 0 ] && error "No bandwidth specified"
            export BANDWIDTH="$1"
            shift;;
        (-t|--timeout)
            shift
            [ $# = 0 ] && error "No timeout specified"
            export TIMEOUT="$1"
            shift;;
        (-p|--port)
            shift
            [ $# = 0 ] && error "No port specified"
            export PORT="$1"
            shift;;
        (-l|--compression-level)
            shift
            [ $# = 0 ] && error "No compression level specified"
            export COMPRESS_LEVEL="$1"
            shift;;
        (-h|--help)
            help;;
#       (-V|--version)
#           version_info;;
        (*) usage;;
        esac
    done
}

flags "$@"