Date: Fri, 2 Feb 2007 13:18:14 -0600 From: Dan Nelson <dnelson@allantgroup.com> To: Jerry McAllister <jerrymc@msu.edu> Cc: Robert Fitzpatrick <lists@webtent.net>, FreeBSD <freebsd-questions@freebsd.org> Subject: Re: Determining daylight savings changes on BSD Message-ID: <20070202191814.GE44511@dan.emsphone.com> In-Reply-To: <20070202175710.GA98134@gizmo.acns.msu.edu> References: <1170430862.16189.8.camel@columbus.webtent.org> <20070202163637.GC44511@dan.emsphone.com> <20070202175710.GA98134@gizmo.acns.msu.edu>
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In the last episode (Feb 02), Jerry McAllister said: > On Fri, Feb 02, 2007 at 10:36:37AM -0600, Dan Nelson wrote: > > In the last episode (Feb 02), Robert Fitzpatrick said: > > > I use the following command on our CentOS Linux servers to find > > > out if the system is ready for the daylight savings changes > > > coming up, but it does not seem to work the same on our FreeBSD > > > 5.4 and 6.1 servers. How can I do this? I see the zdump command > > > and the man page seems to suggest the same usage, but... > > > > > > esmtp# zdump -v US/Eastern | grep 2007 > > > esmtp# zdump -v US/Eastern > > > US/Eastern Fri Dec 13 20:45:52 1901 UTC = Fri Dec 13 20:45:52 1901 UTC isdst=0 gmtoff=0 > > > US/Eastern Sat Dec 14 20:45:52 1901 UTC = Sat Dec 14 20:45:52 1901 UTC isdst=0 gmtoff=0 > > > US/Eastern Mon Jan 18 03:14:07 2038 UTC = Mon Jan 18 03:14:07 2038 UTC isdst=0 gmtoff=0 > > > US/Eastern Tue Jan 19 03:14:07 2038 UTC = Tue Jan 19 03:14:07 2038 UTC isdst=0 gmtoff=0 > > I don't know how to read this. There was another command I saw a while > back that gave similar looking information, but actually put out something > for 2007. But, I can't find that mesage at the moment. > > > That means you need to update your zoneinfo tables. You can also use > > the date command to see if you need updating: > > > > date -r 1173679260 > > > > If that prints "Mon Mar 12 02:01:00 EST 2007" you know you need to > > update. > > Are you sure? I see the EST where mine says EDT, but mine gives the > exact same date/time information as you show above outside of the EST. > > If I subtract out exactly one day (86400 seconds) I get: > Sun Mar 11 01:01:00 EST 2007 which is just 59 minutes before > the changeover. > > Then, if I add an hour (3600 seconds) I get: > Sun Mar 11 03:01:00 EDT 2007 So you're saying that for dates on March 11 after 2AM, you get EDT, but on March 12 it's back to EST? That doesn't make sense :) I get: $ TZ=America/New_York ; export TZ $ date -r 1173592860 Sun Mar 11 01:01:00 EST 2007 $ date -r 1173596460 Sun Mar 11 03:01:00 EDT 2007 $ date -r 1173679260 Mon Mar 12 02:01:00 EDT 2007 $ > So, I would expect the non-updated system to give: > Mon Mar 12 01:01:00 EST 2007 Yes, that's what a system without the updated zoneinfo should print, I think. > Or is something else really messed up? > My system seems to be giving the correct current date/time. -- Dan Nelson dnelson@allantgroup.com
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