comp.os.linux.networking

In article ,
ibuprofin@painkiller.example.tld (Moe Trin) writes:
> On Sun, 16 Mar 2008, in the Usenet newsgroup comp.os.linux.networking, in
> article , EricThompson wrote:
.....
>>It's quite a luxury, and we're paying a price for it now in the
>>difficulty to which this little discussion alludes. We now have a
>>world economy to deal with, and travel that within hours takes us to
>>"other days."
>
> International broadcasters seem to have no problem using "GMT" (sic)
> as do multi-national file systems.
>

Exactly: Unix, grabbed the concept very early on. Filesystems and
computers' clocks need to use an invariant time (let's ignore the leap
seconds). The problem that any system which uses a civil time which
jumps back and forwards due to DST will face is that each year there
will be an hour's worth of times which are missing, and even worse an
hour's worth of times with an ambiguous meaning. (OK 30 minutes in the
case of Australia/Lord_Howe and Pacific/Rarotonga, as is revealed later
in Old Guy's post)

The solution Unix adopted was simple and elegant: store times in
UTC/GMT, but display them in the user's civil time as and when required.

I know MSDOS and the FAT filesystem ran the clock in, and stored, civil
time. Thus if one had two files on a system in the UK:
A created at 01:15:00 on October 28th 2007
B created at 01:40:00 on October 28th 2007
it would be impossible to say which file is older. It may be that B was
created first at 00:40:00 UTC when the civil time was 01:40:00 due to
daylight saving, while A was created later at 01:15:00 UTC when daylight
saving had ended. Or, of course, they may have been created both in
daylight saving, or both outside daylight saving, so A is older than B.

Having an operating system and filesystem which can't tell which file is
older is obviously a major problem. I know NTFS now uses UTC/GMT, but
are there any remaining issues with XP/Vista + NTFS and timestamps, or
has it really managed to catch up with Unix/Linux and its simple and
elegant way of handling the issue?

Of course some might say it doesn't really matter with operating systems
where the computer is rarely able to to anything without a user chained
to it by mouse and keyboard, actually doing the work. Because files are
rarely created at between 1 and 2 am. But then I wouldn't want to make
such cheap remarks :-)

--
Tim Clark