From owner-freebsd-arch  Tue Jun  5 13: 1:31 2001
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To: Matt Dillon <dillon@earth.backplane.com>
Cc: Greg Lehey <grog@FreeBSD.ORG>,
	"Daniel O'Connor" <doconnor@gsoft.com.au>, freebsd-arch@FreeBSD.ORG,
	huntting@glarp.com
Subject: Re: changing timezones 
In-Reply-To: Your message of "Mon, 04 Jun 2001 19:50:19 PDT."
             <200106050250.f552oJC34814@earth.backplane.com> 
Date: Tue, 05 Jun 2001 14:01:18 -0600
From: Brad Huntting <huntting@glarp.com>
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> I think you missed the original article.  The idea was to try to
> have a running programming automatically detect the timezone change
> and adjust its internal state accordingly.  Doing that automatically
> without the programming knowing isn't a good idea.

I doubt there are many programs that would mind having the timezone
change.  They already have to cope with daylight saving changes.

> Adding code to sendmail, syslogd, cron, etc... to detect the change
> at a safe point, on the other hand, might be interesting.  But,
> ultimately, I think it would be kind of a waste of programming
> hours to do.

Changing IP addresses or DNS nameserver addresses used to involve
a reboot and that was reasonable at the time because machines didnt
change addresses very often.  Changing usage patterns called for
a better solution.

Similarly, we need to be able to handle the typical usage patterns
of mobile workstations as they will only becoming more popular.
And IMHO, changing timezones qualifies as a typical event for a
mobile workstation.

That said, I dont think it's unreasonable to require a HUP for
servers that are sensitive to timezone changes.  My main question
is:

	Should calling tzset() or tzsetwall() force /etc/localtime
	or the TZ environment variable to be rescaned?

	Should calling localtime() rescan /etc/localtime and/or
	$TZ?


brad

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