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From: guy@auspex.auspex.com (Guy Harris)
Newsgroups: comp.mail.uucp
Subject: Re: UUCP status files and wierd dates.
Message-ID: <4412@auspex.auspex.com>
Date: 16 Nov 90 19:03:20 GMT
References: <736@dynasys.UUCP> <803@sci34hub.UUCP>
Organization: Auspex Systems, Santa Clara
Lines: 26

>The date is the internal format, which is defined as the number of seconds
>since January 1, 1970.

January 1, 1970, midnight *GMT* (or UTC), specifically - i.e., the
correct value for the internal time on *all* UNIX machines on Planet
Earth, as of the moment I the the last character in this sentence, is
the same (most machines, in practice, probably don't have the *exact*
correct value, of course...).

>(Reportedly day 0, year 0, of the age of Unix.)

Possible, but unlikely.  The original PDP-7 (*sic*) UNIX is, in an
article by Ritchie and Thompson, claimed to have first shown up in 1969;
unless it showed up *very late* in 1969, it couldn't have been January
1, 1970, midnight GMT.

>All Unix dates are maintained in this format, for some reason;

One reason is that, as indicated above, internal UNIX dates don't have
to worry about time zones, daylight savings time, etc.  That's why the
timer (generally) in the kernel maintains time in that format; that
timer is used to time-stamp files, and is the timer you get when you ask
the OS for the current time.  Since it's the timer you get when you ask
the OS for the current time, and you have to do more work to convert it
into local time, most programs tend to store it rather than some
representation of local time.