#!/usr/bin/env bash
  
  #
  # Copyright (C) 2015 Eistec AB
  #
  # This file is subject to the terms and conditions of the GNU Lesser General
  # Public License v2.1. See the file LICENSE in the top level directory for more
  # details.
  #
  
  # Find all USB to serial devices
  
  # default error status code
  status=1
  
  # iterate over usb-tty devices:
  for basedev in $(find /sys/bus/usb/devices/ -regex "/sys/bus/usb/devices/[0-9]+[^:/]*" -maxdepth 2 -follow 2>/dev/null); do
      ttydirs=$(find ${basedev} -regex "${basedev}/[^/]*:.*" -mindepth 2 -maxdepth 3 -name tty -follow 2>/dev/null)
      if [ -z "${ttydirs}" ]; then
          continue
      fi
      # See if the device has any tty devices assigned to it
      for tty in $(find ${ttydirs} -maxdepth 1 -mindepth 1 -printf '%f\n' 2>/dev/null); do
          parent=$(echo ${basedev} | sed -e 's%\(/sys/bus/usb/devices/[^/]*\)/.*%\1%')
          serial=$(cat "${parent}/serial" 2>/dev/null)
          # split results into array
  
          if [ $# -lt 1 ]; then
              # No arguments given, return all ttys
              echo "/dev/${tty}"
              status=0
              continue
          fi
          # else: Match any of the given serials
          for s in "${@}"; do
              echo "${serial}" | egrep -e "${s}" -q
              if [ $? -eq 0 ]; then
                  # return tty
                  echo "/dev/${tty}"
                  status=0
              fi
          done
      done
  done
  
  exit $status;