Daylight saving

[Khashru]

I am runninh hpux 11i. Our daylight saving will end on 2nd september.

What are the action i need to do for automatic update system time?

[Rajeev Shukla]

If your have the correct timezone for your system defined then the system will take care of the daylight saving.

You could verify this by having a look at the /usr/lib/tztab file. Look for your time zone (TZ) and that should tell you the dates when the system will take care of daylight.

[Arunvijai_4]

Hi Khashru,

Check these threads for more information,

http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=967582
http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=136176

-Arun

[Khashru]

I have the following settings

EST-10EDT#NSW
0 3 25-31 10 1971-1999 0 EDT#NSW-11
0 3 27 8 2000 0-6 EDT#NSW-11
0 3 25-31 10 2001-2038 0 EDT#NSW-11
0 1 27 2 1972 0-6 EST-10
0 1 1-7 3 1973-1985 0 EST-10
0 1 15-21 3 1986 0 EST-10
0 2 1-7 3 1987-1995 0 EST-10
0 2 25-31 3 1996-2038 0 EST-10

How to interpret it?

[Senthil Kumar .A_1]

Hi,

Got the details in "man 4 tztab"

EXAMPLES
The time zone adjustment table for the Eastern Time Zone in the United States is:

EST5EDT
0 3 6 1 1974 0-6 EDT4
0 3 22-28 2 1975 0 EDT4
0 3 24-30 4 1976-1986 0 EDT4
0 3 1-7 4 1987-2038 0 EDT4
0 1 24-30 11 1974 0 EST5
0 1 25-31 10 1975-2038 0 EST5

Normally (as indicated in the first line) Eastern Standard Time is five hours earlier than UTC. During Daylight Savings time, it changes to a 4 hour difference. The first time Daylight Savings Time took effect (second line) was on January 6, 1974 at 3:00 a.m., EDT. Note that the minute before was 1:59 a.m., EST. The change back to standard time took effect (sixth line) on the last Sunday in November of the same year. At that point, the time went from 1:59 a.m., EDT to 1:00 a.m., EST. The transition to Daylight Savings Time since then has gone from the last Sunday in February (third line) to the last Sunday in April (fourth line) to the first Sunday in April (fifth line). The return to standard time for the same period has remained at the last Sunday in October (seventh line).

For more details....

http://docs.hp.com/en/B2355-60105/tztab.4.html

Regards,
Senthil Kumar .A

[Rajeev Shukla · Accepted solution]

The first field is minutes and second is hour, third is date and fourth is the month and 5th is year and the 6th is day where 0=sunday and 6=saturday and the 7th says the offset from GMT

So when you have a line say
0 3 6 1 1974 0-6 EDT4
this means that the clock turned to a GMT offset of +4 at 3:00 am on 6th of January on 1974

when you have a line say, where the 6th field is 0 means sunday
0 1 1-7 3 1973-1985 0 EST-10

So we say that the clock turned to a GMT offset of -10 at 1:00am on the first sunday falling between 1st to 7th of march between 1973 to 1985

[A. Clay Stephenson]

After making your tztab entries, you can check your system with the attached perl script, dst.pl. It will display the exact second before and after the time change. It uses exactly the same routines as the date command and standard UNIX utilities do so if the Perl script works, everything else works as well.

Invoke as dst.pl -u for full usage.

[TwoProc]

HP is recommending that you install 3 patches to make sure that the transition is handled correctly(Aside-They call them "DST" time changes - does anyone know why them call them this?).
PHCO_34375(11.23)
PHCO_34342(11.11)
PHCO_34266(11.00)

[Jeff Schussele]

Hi John,

DST = Daylight Savings Time

Rgds,
Jeff

[Robert-Jan Goossens_1]

John,

Patchinfo

---
( SR:8606421293 CR:JAGaf81122 )
For the Commonwealth games to be held in Melbourne Australia in 2006, the DST is shifted by one week for year 2006. DST
will be shifted from last Sunday of March to first Sunday of November for the year 2006.

Resolution:
tztab(4) file has been modified to reflect Australian DST changes.

( SR:8606429356 CR:JAGaf88822 )
According to US government law, the DST start and end is shifted to second Sunday of March and first Sunday of November, respectively from year 2007 onwards.

Resolution:
tztab(4) file has been modified to support US time zone changes.
---
Regards,
Robert-Jan

[TwoProc]

OK Jeff ... my first morning coffeee is still not finished yet. Arrggggh... MIFD (man I feel dumb).

[TwoProc]

Thanks Robert for the information. I was wondering what was up with the change, and had no idea why.

[Khashru]

I got all the required information.