sys_to_usbbus

#!/bin/bash
#
#(c) 2008 Luciano Rocha (luciano@nsk.pt) Armindo Silva (deathon2legs@gmail.com)
#
#Permission to use, copy, modify, and/or distribute this software for any
#purpose with or without fee is hereby granted, provided that the above
#copyright notice and this permission notice appear in all copies.

#THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
#WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
#MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
#ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
#WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
#ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
#OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
#

err() { echo "${FUNCNAME:+$FUNCNAME: }$*" 1>&2; exit 1; }

PATH=$PATH:/usr/sbin:/sbin

[ $# -eq 1 ] || err "$0 <device>"

dev=$(udevadm info --name=$1 --query=path) || exit 1

if [ -n "${dev##/devices*}" ]; then
	# use readlink to get to the device
	dev=$(readlink -f /sys/$dev/device)
fi

[ -n "$dev" ] || err "invalid device specification: $1"

udevadm info -e | grep -B1 bus/usb/ | (
	usb=
	l=0

	while read p sys && read n usbdev && { read dash ||:; }; do
		if echo $dev | fgrep -q -- $sys && [ ${#sys} -gt $l ]; then
			usb=$usbdev
			l=${#sys}
		fi
	done
	[ -n "$usb" ] || err "not an usb device: $1"
	echo $usb
)