strptime on Unix systems

[Justin Sheehy]

"Malcolm Tredinnick" <malcolmt at smart.net.au> writes:

> The following does *not* work under Linux (at least):
> 
> import time
> format = '%a %b %d %H:%M:%S %Z %Y'
> t = time.localtime(time.time())
  ^
(I assume that you meant `tt', and not `t'...

> timestring = time.strftime(format, tt)		# Works OK
> timetuple = time.strptime(tt, format)		# Throws ValueError
> 
> The reason for this problem is that strftime and strptime are based
> on their C-library counterparts and according the man pages, while
> strftime does take a %Z modifier in the format string, strptime does
> NOT understand this modifier.  (so you can remove the %Z from format
> and the above snippet is fine.)

Really?

I would expect it to break regardless of the value of `format'.  You
are passing a tuple as the first argument to time.strptime, which is
expecting a string.

However, there does seem to be a linux problem here.

Under FreeBSD and Solaris, at least, the time module works fine with
the above format string:

Python 1.5.2 (#3, Aug 24 1999, 15:55:20)  [GCC 2.7.2.1] on freebsd3
Copyright 1991-1995 Stichting Mathematisch Centrum, Amsterdam
>>> from time import *
>>> t = time()
>>> format = '%a %b %d %H:%M:%S %Z %Y' 
>>> int(t) == (mktime(strptime(strftime(format, localtime(t)),
format)))
1

But under linux:

Python 1.5.2 (#1, Oct 22 1999, 16:54:21)  [GCC 2.7.2.3] on linux2
Copyright 1991-1995 Stichting Mathematisch Centrum, Amsterdam
>>> from time import *
>>> t = time()
>>> format = '%a %b %d %H:%M:%S %Z %Y' 
>>> int(t) == (mktime(strptime(strftime(format, localtime(t)),
format)))
Traceback (innermost last):
  File "<stdin>", line 1, in ?
ValueError: format mismatch

Indeed, looking at the manual page for the linux system call
strptime(), it does not seem to accept %Z as a format specifier.

-Justin