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I have to create an "Expires" value 5 minutes in the future, but I have to supply it in UNIX Timestamp format. I have this so far, but it seems like a hack.

def expires():
    '''return a UNIX style timestamp representing 5 minutes from now'''
    epoch = datetime.datetime(1970, 1, 1)
    seconds_in_a_day = 60 * 60 * 24
    five_minutes = datetime.timedelta(seconds=5*60)
    five_minutes_from_now = datetime.datetime.now() + five_minutes
    since_epoch = five_minutes_from_now - epoch
    return since_epoch.days * seconds_in_a_day + since_epoch.seconds

Is there a module or function that does the timestamp conversion for me?

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9 Answers

up vote 242 down vote

Another way is to use time.mktime:

future = datetime.datetime.now() + datetime.timedelta(minutes=5)
return time.mktime(future.timetuple())

It's also more portable than %s flag to strftime — latter is not supported on win32.

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9  
You beat me by a few moments. Why not datetime.timedelta(minutes=5) instead? – D.Shawley May 5 '10 at 19:02
3  
Bah, I'm never sure what arguments timedelta actually takes. Edited. – Cat Plus Plus May 5 '10 at 19:04
14  
It's worth noting that this doesn't take microseconds into account, which is included in Python's normal UNIX time representation (ie, time.time()). You'd need to add the datetime.microsecond / 1000000. to the result of time.mktime(). – Joe Shaw Nov 23 '11 at 21:40
18  
Note that time.mktime assumes the timetuple is local, not UTC. If is UTC, use calendar.timegm – tumbleweed Dec 17 '11 at 23:58
5  
.timetuple() sets DST flag to -1 so there is 50% chance your code introduces an one hour error during a daylight-savings-time transition. See Problems with Localtime. – J.F. Sebastian Aug 14 '12 at 14:49
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up vote 69 down vote accepted

Just found this, and its even shorter.

import time
def expires():
    '''return a UNIX style timestamp representing 5 minutes from now'''
    return int(time.time()+300)
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8  
This doesn't answer the question. – Jesse Dhillon Apr 6 '12 at 3:30
10  
@JesseDhillon it answers the question (make a UNIX timestamp 5 mins in future), just not the title. – dbr Jul 7 '12 at 13:56
2  
time.time() can be set back. To create an "Expires" value 5 minutes in the future you might need time.monotonic() analog depending on your use-case. – J.F. Sebastian Aug 14 '12 at 15:00
up vote 33 down vote

You can use datetime.strftime to get the time in Epoch form, using the %s format string:

def expires():
    future = datetime.datetime.now() + datetime.timedelta(seconds=5*60)
    return int(future.strftime("%s"))
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20  
This is a somewhat undocumented behaviour ( python.org/doc/current/library/datetime.html ). Seems to be working under linux and not working under win32 (generating ValueError: Invalid format string). – Antony Hatchkins Dec 25 '10 at 21:23
up vote 4 down vote

The key is to ensure all the dates you are using are in the utc timezone before you start converting. See http://pytz.sourceforge.net/ to learn how to do that properly. By normalizing to utc, you eliminate the ambiguity of daylight savings transitions. Then you can safely use timedelta to calculate distance from the unix epoch, and then convert to seconds or milliseconds.

Note that the resulting unix timestamp is itself in the UTC timezone. If you wish to see the timestamp in a localized timezone, you will need to make another conversion.

Also note that this will only work for dates after 1970.

   import datetime
   import pytz

   UNIX_EPOCH = datetime.datetime(1970, 1, 1, 0, 0, tzinfo = pytz.utc)
   def EPOCH(utc_datetime):
      delta = utc_datetime - UNIX_EPOCH
      seconds = delta.total_seconds()
      ms = seconds * 1000
      return ms
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1  
note: I don't understand "the [unix] timestamp in a localized timezone". The timestamp is the same (elapsed seconds since 1970-01-01 00:00:00+00:00). To get a naive datetime object in local timezone: datetime.fromtimestamp(ts) – J.F. Sebastian Aug 14 '12 at 9:37
up vote 3 down vote

Here's a less broken datetime-based solution to convert from datetime object to posix timestamp:

future = datetime.datetime.utcnow() + datetime.timedelta(minutes=5)
return (future - datetime.datetime(1970, 1, 1)).total_seconds()

See more details at Converting datetime.date to UTC timestamp in Python.

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up vote 2 down vote 
def in_unix(input):
  start = datetime.datetime(year=1970,month=1,day=1)
  diff = input - start
  return diff.total_seconds()
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up vote 1 down vote

Now in Python >= 3.3 you can just call the timestamp() method to get the timestamp as a float.

import datetime
current_time = datetime.datetime.now()
unix_timestamp = current_time.timestamp()
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up vote 0 down vote 
def expiration_time():
    import datetime,calendar
    timestamp = calendar.timegm(datetime.datetime.now().timetuple())
    returnValue = datetime.timedelta(minutes=5).total_seconds() + timestamp
    return returnValue
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up vote 0 down vote

This is what you need:

import time
import datetime
n = datetime.datetime.now()
unix_time = time.mktime(n.timetuple())
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How is this different or adds to the one 'Cat Plus Plus' provided? – David Apr 30 at 19:19

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