#!/usr/bin/env python

import sys, re

def parse_devpath(devpath):
    """
    Parse the devpath of a USB mass storage device into a path that identifies which physical USB port it is connected to
    bus/port, bus/port/port/port

    >>> parse_devpath("/devices/pci0000:00/0000:00:1d.7/usb2/2-1/2-1.1/2-1.1.1/2-1.1.1:1.0/host16/target16:0:0/16:0:0:0/block/sdb1")
    "usb/2/1/1/1"
    >>> parse_devpath("/devices/pci0000:00/0000:00:1d.7/usb2/2-2/2-2:1.0/host12/target12:0:0/12:0:0:0/block/sdb1")
    "usb/2/2"
    """
    path = devpath.split("/usb")[1]
    path = path.split(":")[0]
    path = path.split("/")[-1]
    path = path.replace("-", "/")
    path = path.replace(".", "/")
    path = "usb/" + path

    return path

if __name__ == '__main__':
    print parse_devpath(sys.argv[1])