bash script to give USB device information from a node in /dev

blk2usb.sh

#!/bin/bash
# Brian Ronald, 2019
# Tested in Ubuntu 18.04
# Free for all purposes, no warranty at all.

if [ $# -eq 0 ]
then
	echo "Usage: $0 <block device node>"
	echo "Show the USB device associated with a block device"
	exit
fi

if [ ! -b $1 ]
then
	echo "Specified argument is not a block device node"
	exit 1
fi	

# Ask lsblk for the major and minor nodes, using xargs to strip whitespace
BlockDevice=$(lsblk -ldn $1 -oMAJ:MIN | xargs)

# Look at the device file symlinked in /sys/dev/block to get the device path
DevicePath=$(readlink -f /sys/dev/block/$BlockDevice)

# Look at the path to determine the presence of a USB device
USBPath=$(echo $DevicePath | grep -Po '^/.*usb./.*?/')

if [ -z $USBPath ]
then
	echo "Specified device is not connected to USB"
	exit 2
fi

# Use the busnum and devnum to get the USB information from lsusb
lsusb -s $(cat $USBPath/busnum):$(cat $USBPath/devnum)