tztab file

[RUSSOCKI Wladyslaw]

How is used the tztab file by HP-UX. To test the future change of daylight time zone, I have done a test, successless:
my config:
echo $TZ
MET-1METDST

vi /usr/lib/tztab

# Middle European Time, Middle European Time Daylight Savings Time
MET-1METDST
0 3 25-31 3 1983-2038 0 METDST-2
0 2 24-30 9 1983-1995 0 MET-1
30 17 25-31 10 1996-2038 4 MET-1

it is now 17:35 and nothing happens!
why ?

thank's

[John Palmer]

Hi,

You appear to have changed the original line
0 2 25-31 10 1996-2038 0 MET-1 to:
30 17 25-31 10 1996-2038 4 MET-1

If you want daylight saving to end today at 17:30 then you will have to change the '25-31' entry to 12 (the day of the month) or a range of days containing 12. You have set it to whatever Thursday occurs between the 25th and 31st of October at 17:30.

See 'man tztab' for all the information but I agree that it's confusing.

Regards,
John

[Alex Glennie]

try :

# Middle European Time, Middle European Time Daylight Savings TimeMET-1METDST
0 3 25-31 3 1983-2038 0 METDST-20 2 24-30 9 1983-1995 0 MET-1
0 2 25-31 10 1996-2038 0 MET-1

in tztab file ?

[RUSSOCKI Wladyslaw]

SORRY!
That's a cut and past error, my exact taztab file was in fact:

25 17 11-17 10 1996-2038 4 MET-1

but even with this config nothing happened...

[Kofi ARTHIABAH]

No Isreal, leave the entry as:
0 2 25-31 10 1996-2038 0 MET-1
the above means:
On the last sunday (ie. first sunday between the 25th and 31st of October) for the years 1996 - 2038, adjust the time at 2am.

Because you have not set the time to within the last sunday of October, the change will not happen.

There are a couple of things you could do to test -
1. leave the default as-is and manually set (advance the date) with SAM
2. change the 25-31 entry and the 0 entry to the date ranges that your test dates fall on.

Good luck
PS. i would rather go with option 1. - it leaves things the way they were meant to be :-)

[John Palmer · Accepted solution]

I think that the time specified is one hour out. If you change it to 25 16 ... then it works.

Regards,
John

[RUSSOCKI Wladyslaw]

John: you're right!
In fact if you change the tztab file more than one hour sooner than the fatidic date , it works! that is to say that if it is 9 AM
and you configure the tztab file like that:
0 11 11-17 1996-2038 5 MET-1
when it is 12, the change happens and it is 11...

but for instance if it is 12:06
even if you configure your file for 13:00 it won't work ...

thank's

[Fedon Kadifeli]

Use the attached Perl script to test tztab changes. Also check that your /etc/TIMEZONE is correct.

[John Palmer]

Yes, when you specify the line:-

0 11 11-17 1996-2038 5 MET-1

the 11 refers to 11:00MET which is 12:00METDST hence the hour difference.

Regards,
John