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tztab file change effect

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ShaileshBhanderi
Occasional Advisor

tztab file change effect

Hi All,

I have question about tztab file change.
we have situation like customer want to change daylight saving time. Right now everything is define and time will change at 3hrs of march last week Sunday according to tztab but customer required that DST should effect from 4hrs.
/usr/lib/tztab :
WST-4WSTDST
0 3 25-31 3 1983-2038 0 WSTDST-5
0 2 24-30 9 1983-1995 0 WST-4
0 2 25-31 10 1996-2038 0 WST-4
/etc/TIMEZONE :
TZ=WST-4WSTDST
export TZ

My question is:
If I will change tztab file, WST-4WSTDST hours to 4. Will change required system reboot or it will work with out system reboot?
Please I appreciate your help asap.

BR
Shailesh
6 REPLIES
Ganesan R
Honored Contributor
Solution

Re: tztab file change effect

Hi,

DST changes will not require system reboots. Time will be adjusted automatically as per the tztab file.
Best wishes,

Ganesh.
Sharma Sanjeev
Respected Contributor

Re: tztab file change effect

Hi Shailesh

No Reboot required for this.

Regards
Sanjeev
Everything is Possible as " IMPOSSIBLE" word itself says I M POSSIBLE
Dennis Handly
Acclaimed Contributor

Re: tztab file change effect

Using Clay's dst.pl script, I get:
$ TZ=WST-4WSTDST dst.pl
Sun Mar 29 01:59:59 WST 2009 --> Sun Mar 29 03:00:00 WSTDST 2009
Sun Oct 25 02:59:59 WSTDST 2009 --> Sun Oct 25 02:00:00 WST 2009

Are you saying you want to change the official timezone start to 0400?
Changing /etc/tztab will prevent any future tztab patches from installing without manual intervention.

>Will change required system reboot

It depends. If you want cron to work with this new TZ, you would have to restart it or wait/ignore until 4 am.

Other demons may have issues too, syslog will continue using the old TZ values.
ShaileshBhanderi
Occasional Advisor

Re: tztab file change effect

Hi,

Answer to your questions.

1) yes, that's correct. Official timzone need to modify and should start to 0400(DST). it apply same for reverse 0300(DST).
2) I have lots of cron and it should work. My idea is I will modify only tztab with DST parameters(aware about patch),
so time will not changed right now (No new TZ, modify original TZ), only change will apply to DST which will effect on 29th March-09.

My question again, Will it work without server reboot?

BR
Shailesh
Suraj K Sankari
Honored Contributor

Re: tztab file change effect

Hi,
Is your system is having DST patch ?
then no need to worry....
Patch will take care of your time..

Suraj
Dennis Handly
Acclaimed Contributor

Re: tztab file change effect

>2) I have lots of cron and it should work.

Then you need to stop/restart cron.

>Will it work without server reboot?

It depends on how many other demons you want to work with the new time in that hour.

>Suraj: Is your system is having DST patch?

If you edit tztab, you will have to manually patch it in the future.