Look for a specified USB device

gistfile1.sh

#!/bin/bash

# Specify the product ID of your device
DEVICE="0x2838"

# the command to list USB devices
USB_DEVICE_CMD="system_profiler SPUSBDataType"

# get the list and filter for the device we're looking for
DEVICE_PRESENT=`$USB_DEVICE_CMD | grep $DEVICE | cut -f2 -d':'`

if [ "$DEVICE_PRESENT" == " $DEVICE" ]; then
	# Do things in this section if the device is found
	echo "Device found"
else
	# Do the things in this section when it's missing
	echo "Device removed!"
	say "Alert! Device has been removed"
	#afplay /path/to/some/sound.mp3
fi