read_serial.py

import serial

# Source: https://pyserial.readthedocs.io/en/latest/shortintro.html#opening-serial-ports
# Additional info:
# * you have to install pyserial in order for this code to work, command `sudo pip install serial`
# * run this script with sudo: `sudo python read_serial.py`

with serial.Serial('/dev/ttyUSB0', 9600, timeout=1) as ser:
    while True:
        # read a '\n' terminated line
        line = ser.readline()
        print(line)