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