Script to poll for the buttons on a scanner and run a script if pressed. Currently just checks if any button is pressed, but could be easily adjustable.

scan.sh

#!/bin/bash -e

FOLDER="/home/roman/Scanned/"

PORT="$(lsusb | grep CanoScan | pcregrep -o1 "Bus ([0-9]*)")"
DEVICE="$(lsusb | grep CanoScan | pcregrep -o1 "Device ([0-9]*)")"

SCANBD_DEVICE="genesys:libusb:${PORT}:${DEVICE}"

scanimage --format jpeg -d ${SCANBD_DEVICE} --source Flatbed --resolution 300 -o /tmp/scan.jpg
tesseract /tmp/scan.jpg "${FOLDER}/scan_$(date +'%FT%T')" -l deu pdf

scanbuttondaemon.py

import sane
import time
import argparse
import os
import subprocess

parser = argparse.ArgumentParser(description="If any button on the scanner is pressed, run the script.")
parser.add_argument("script", help="Path to script which should be run on button press.")
parser.add_argument("--pollinginterval", default=1.0, help="Polling interval in seconds.")
parser.add_argument("--devicesubstring", default="LiDE 200", help="Substring to look for in device name.")
args = parser.parse_args()

while True:
	try:
		print("Initializing...")

		sane.init()
		device = next(d for d in sane.get_devices() if args.devicesubstring in str(d))
		interface = sane.open(device[0])
		options = [o[0] for o in interface.dev.get_options() if "button" in str(o)]

		print("Polling...")

		while True:
			for o in options:
				try:
					is_pressed = interface.dev.get_option(o)==1
				except:
					is_pressed = False
					if args.devicesubstring not in str(subprocess.check_output("lsusb")):
						interface.close()
						raise Exception("not connected!")
				if is_pressed:
					interface.close()
					print("Running script...")
					result = os.system(args.script)
					interface = sane.open(device[0])
		time.sleep(args.pollinginterval)
	except Exception as e:
		print(e)
		sane.exit()
		print("Device not working or not connected, sleep for a couple of seconds...")
		time.sleep(10)