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Date: | Thu, 1 Mar 2007 17:09:59 -0800 |
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Greetings. This could be sub-titled "When is Los Angeles != Tijuana?".
I suppose this a mainly a west-coast issue, but in the past I have
often chosen "America/Tijuana" as our time zone when installing SL or
the upstream distribution. It just seems a little easier to point the
arrow on the map to Tijuana, and both places have been listed as
US/Pacific, so how could it matter?
Now it seems that it DOES matter. We've just started to look into the
ramifications of the looming implementation of the changes in the rules
for Daylight Savings Time (DST). It appears that there has been a
tzdata update for almost a year that supposedly deals with the new rules.
Evidently, one can check that the update has been installed by using the
"zdump" command (see the appended). On the first system we checked, the
time zone was set to "America/Tijuana", and the zdump check showed the
OLD DST rules were in effect.
We re-ran system-config-date and selected, as the only change, the time
zone "America/Los_Angeles". A subsequent run of zdump showed that the
NEW DST rules were now being used for that zone.
Thus, I believe that the story has a happy ending, at least for this
system. But I would like not to have to run an interactive utility on
every system for which we have to make this change. It would be easy
enough (sed or equivalent) to make an automated edit of
/etc/sysconfig/clock.
On the other hand, it appears that the time-zone information must also
be reflected in the data file /etc/localtime.
My first question is: is the time-zone information stored any place
besides the two files /etc/sysconfig/clock and /etc/localtime?
And regarding /etc/localtime: I don't know the format of the file, but
in all of the systems in our classroom the file /etc/localtime has
exactly the same size (1017 bytes) and has exactly the same "strings"
output.
My second question: is it safe to assume that any two systems at the
same revision of SL and in the same time zone have exactly the same
contents in /etc/localtime?
Thanks.
- Mike
[root@xxxxxx sysconfig]# cat clock
ZONE="America/Tijuana"
UTC=true
ARC=false
[root@xxxxxx sysconfig]# zdump -v "America/Tijuana" | grep 2007
America/Tijuana Sun Apr 1 09:59:59 2007 UTC = Sun Apr 1 01:59:59 2007
PST isdst=0 gmtoff=-28800
America/Tijuana Sun Apr 1 10:00:00 2007 UTC = Sun Apr 1 03:00:00 2007
PDT isdst=1 gmtoff=-25200
America/Tijuana Sun Oct 28 08:59:59 2007 UTC = Sun Oct 28 01:59:59 2007
PDT isdst=1 gmtoff=-25200
America/Tijuana Sun Oct 28 09:00:00 2007 UTC = Sun Oct 28 01:00:00 2007
PST isdst=0 gmtoff=-28800
[root@xxxxxx sysconfig]# system-config-date
(change only the time zone: America/Los_Angeles)
[root@xxxxxx sysconfig]# cat clock
ZONE="America/Los_Angeles"
UTC=true
ARC=false
[root@xxxxxx sysconfig]# zdump -v "America/Los_Angeles" | grep 2007
America/Los_Angeles Sun Mar 11 09:59:59 2007 UTC = Sun Mar 11 01:59:59
2007 PST isdst=0 gmtoff=-28800
America/Los_Angeles Sun Mar 11 10:00:00 2007 UTC = Sun Mar 11 03:00:00
2007 PDT isdst=1 gmtoff=-25200
America/Los_Angeles Sun Nov 4 08:59:59 2007 UTC = Sun Nov 4 01:59:59
2007 PDT isdst=1 gmtoff=-25200
America/Los_Angeles Sun Nov 4 09:00:00 2007 UTC = Sun Nov 4 01:00:00
2007 PST isdst=0 gmtoff=-28800
--
Michael Hannon mailto:[log in to unmask]
Dept. of Physics 530.752.4966
University of California 530.752.4717 FAX
Davis, CA 95616-8677
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