epoch seconds from a datetime

[Chris Rebert]

On Thu, Aug 28, 2008 at 10:18 AM, Richard Rossel <henhiskan at gmail.com> wrote:
> Hi friends,
> I need a little help here, I 'm stuck with epoch calculation issue.
> I have this datetime:
> date_new = datetime(*time.strptime('20080101T000000','%Y%m%dT%H%M%S')
> [0:6])
> This date_new is in UTC
> Now I need to know the seconds since epoch of this new date, so I run
> this:
> seconds = int(time.mktime(date_new.timetuple()))
> but the seconds returned belongs to :
> Tue, 01 Jan 2008 03:00:00 GMT
> because the  localtime is in timezone 'America/Santiago': -3
>
> I fix this trying to alter the TZ with time.tzset():
>  os.environ['TZ'] = 'UTC'
> time.tzset()
>
> .... and now I can gets the right epoch, but I can't restore the
> previous TimeZone, I try with:
> os.environ['TZ'] = '', but the time.tzset() doesn't back to the
> original ( America/Santiago)

I think you need to del os.environ['TZ'] rather than setting it to the
empty string.

On my box:
Python 2.5.1 (r251:54863, Feb  4 2008, 21:48:13)
[GCC 4.0.1 (Apple Inc. build 5465)] on darwin
>>> import os, time
>>> time.asctime()
'Thu Aug 28 11:19:57 2008'
>>> #that's my correct local time
>>> time.tzname
('PST', 'PDT')
>>> #that's my correct timezone
>>> os.environ['TZ'] = 'UTC'
>>> time.tzset()
>>> time.tzname
('UTC', 'UTC')
>>> time.asctime()
'Thu Aug 28 18:20:33 2008'
>>> #we're clearly in UTC now
>>> del os.environ['TZ'] #this is the key line
>>> time.tzset()
>>> time.tzname
('PST', 'PDT')
>>> time.asctime()
'Thu Aug 28 11:21:05 2008'
>>> #and now we're back to my original timezone

Regards,
Chris
========
Follow the path of the Iguana...
Rebertia: http://rebertia.com
Blog: http://blog.rebertia.com

>
> A solution should be set the os.environ['TZ']   to  'America/Santiago'
> but I can't make a TZ hardcode because
> the software should works on different timezones.
>
> So the question, how can restore the system into original timezone, or
> how to know the seconds since epoch
> from UTC datetime without change the local system TIMEZONE.
>
> please help
>
> --
> http://mail.python.org/mailman/listinfo/python-list
>