#!/usr/bin/env python

import argparse

parser = argparse.ArgumentParser()
parser.add_argument("pvname")
clargs = parser.parse_args()


from time import sleep
from epics import PV


pvname = clargs.pvname
pv = PV(pvname)

def update(value=None, **kwargs):
    print(value)

pv.add_callback(update)


while True:
    sleep(1)