time change

Jerry Feldman gaf at blu.org
Fri Sep 20 16:25:23 EDT 2002


Lots of very good reasons. The military has used UTC (ZULU time) for many 
years, even before computers. 
I don't remember when Unix started using UTC (probably back when it was 
invented because of the astronomy background). But, it is very important 
for computer networks where you might be sharing files. 
Let's take early Unix where there was only UUCP. It was still very common 
to synchroinize files and have distributed environments. Tools like make(1) 
are very time sensitive. When you have a distributed environment that spans 
a time zone, UTC timestamps are critical. 
Linux had to be able to support both time formats, mainly because of dual 
booting with OS2 and lesser OS wannabes. One of the first things I did on 
my laptop was to set the BIOS to UTC. 
On 20 Sep 2002 at 16:17, K. Ari Krupnikov wrote:
> There is a good reason they invented UTC in the first place - you
> always know when an event occurred relative to some other event,
> e.g. 8 am EST is after, not before 10 am CET. Consequently, when your
> files move from one timezone to another (because you took your laptop
> to Europe or because you emailed a file to the other coast) you still
> know which file is older.

-- 
Jerry Feldman <gaf at blu.org>
Associate Director
Boston Linux and Unix user group
http://www.blu.org PGP key id:C5061EA9
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