バーコードスキャナのHIDデバイスをつないで、コンソールでスクリプトを実行したら入力待ち、スキャンしたら画面に表示する。

barcode.py

#!/usr/bin/python3

#https://codeday.me/jp/qa/20190304/361513.html

import signal, sys
import evdev
from evdev import InputDevice, ecodes, list_devices, categorize

# キースキャンコードとキャラクターの対応リスト
scancodes = {
    # Scancode: ASCIICode
     2: '1',  3: '2',  4: '3', 5: '4',
     6: '5',  7: '6',  8: '7', 9: '8',
    10: '9', 11: '0', 28: 'CRLF'
}

barCodeDeviceString = 'USB BARCODE SCANNER USB BARCODE SCANNER'

devices = map(InputDevice, list_devices())

for device in devices:
    print(device.name)
    if device.name == barCodeDeviceString:
        dev = InputDevice(device.path)

if not 'dev' in locals():
    sys.exit("Device '{barCodeDeviceString}' not connected.".format(**locals()))

def signal_handler(signal, frame):
    print("\nStopping")
    dev.ungrab()
    sys.exit(0)

signal.signal(signal.SIGINT, signal_handler)

dev.grab()

def main():
    code = ''
    for event in dev.read_loop():
        if event.type == evdev.ecodes.EV_KEY:
            data = evdev.categorize(event)
            if data.keystate == 1:  # Down events only
                key_lookup = scancodes.get(data.scancode) or ''
                if key_lookup == 'CRLF':
                    print(code)
                    code = ''
                else:
                    code += key_lookup

if __name__ == '__main__':
    main()