如何在运行时让Python注意到系统时区的变化？

Question

If I change my computer's timezone while a Python program is running, that program continues to use the old timezone for calculations and conversions unless I restart the program.

This causes trouble in situations such as parsing the output of commands which use local time, such as net stats svr in Windows. Converting such a parsed local time to a Unix timestamp with time.mktime(local_naive_datetime.timetuple()) returns an incorrect timestamp unless the program is restarted because it assumes the local time is in the old timezone.

A simple example demonstrating this problem: call datetime.datetime.now() , change the system timezone, and call the function again. The second call returns the local time in the old timezone.

Is there a function or other method I can use to tell Python to recheck the system timezone without restarting a long-running script?

I am running Python 2.7.3 on Windows 7.

Answer 1

Yes there is a function. You can call time.tzset() and you can use time.tzname to get the time zone information.

Please take a look at http://docs.python.org/2/library/time.html#time.tzset

Answer 2

This code worked to detect the change. Not exactly production quality though.

import os
import time
print(time.ctime(time.time()))
inp = input('change time and press enter')
f = open('newtimezone','w')
f.close()
print(time.ctime(os.stat('newtimezone').st_mtime))