topic Re: Time change in Operating System - HP-UX

Time change

Sana Chaarani — Fri, 04 Apr 2003 15:19:16 GMT

Hi,

Quick question : at what time the time change actually happens for daylight savgin time. I know it is the first Sunday in April ( for EST ) but at what hour ?? 2am , 3 am ?

Thanks,

Re: Time change

Patrick Wallek — Fri, 04 Apr 2003 15:21:20 GMT

At 2AM this coming Sunday morning (April 6, 2003) you spring forward 1 hour.

Re: Time change

Ron Cornwell — Fri, 04 Apr 2003 15:22:43 GMT

At 2am the clock will jump to 3am.

Re: Time change

Dario_1 — Fri, 04 Apr 2003 15:37:18 GMT

At 2 AM.

DR

Re: Time change

Adam J Markiewicz — Fri, 04 Apr 2003 16:19:07 GMT

Precise:

Should from 2 to 3.

If you have correctly assigned $TZ to EST5EDT
it will be done automatically by the system according to the definition from /usr/lib/tztab

If you check man tztab
and the above file you should find out that your valid definition line is:
0 3 1-7 4 1987-2038 0 EDT4

Which means:
Definition for EST of DST in the years beginning from the 1987 is:
the first our will be 3.00
do the change in the first week (1-7 is month day)
in April
On Sunday (last 0)

The last field is the official name with an offset from GMT.

Good luck
Adam

Re: Time change

John Bolene — Fri, 04 Apr 2003 17:05:56 GMT

We always shutdown any Oracle databases before the time change happens.

It may not be necessary, but it sure causes strange things to happen if we don't.

Re: Time change

Luigi Cicconi — Fri, 04 Apr 2003 17:36:20 GMT

From the man page of tztab

NOTE- I've taken the "19" out the year field for readability.

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

EST5EDT
0 3 6 1 74 0-6 EDT4
0 3 22-28 2 75 0 EDT4
0 3 24-30 4 76-86 0 EDT4
0 3 1-7 4 87-2038 0 EDT4
0 1 24-30 11 74 0 EST5
0 1 25-31 10 75-2038 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).

Luigi