[nflug] Daylight saviings time

[Mark T. Valites]

What do you mean by "rebuild your whole system"?

Running ntpdate after the new DST goes into effect won't make any 
difference for applications that use localtime. (If your clock is on, it 
likely won't make any difference.) If the timezone data files aren't 
updated with the new DST info, when the coversion to localtime from GMT 
occurs, the localtime reported will be wrong. You must have updated 
timezone data files.


Also keep in mind that the java JRE stores timezone data separate from the 
OS & may need to be update separately:

http://java.sun.com/developer/technicalArticles/Intl/USDST/

Sun JDK US DST Timezone Update Tool:

http://java.sun.com/javase/downloads/index.jsp

-Mark

On Wed, 21 Feb 2007, matt donovan wrote:

> well I have to rebuild my whole system but they say that ntpdate will fix it
>
> On 2/21/07, Robert Meyer <meyer_rm at yahoo.com> wrote:
>> 
>>  This is not true.  Linux/Unix thinks in GMT (UTC for time buffs).  When
>> dates are reported, the library call uses the timezone information from the
>> system to convert it to localtime on the fly.  If your system's library
>> routines (in Unix/linux the timezone files) aren't correct for the timezone
>> change differences, you will have a system that reports the time 
>> incorrectly
>> after the DST change.  So for three weeks, your clock will be off.  If you
>> force the clock to show the correct value, then the system's concept of GMT
>> will be off by an hour.  ntpdate will do everything in GMT on a Linux/Unix
>> box.  It will try to set the system's clock to the proper GMT which means
>> that localtime routines will be off.
>> 
>> Lots of apps use local time to do things, such as cron or any calendering
>> app.  Failure to fix the timezone data will cause those apps to be wrong.
>> 
>> I know this 'cuz I just had to patch a whole pile of machines at work,
>> lest our apps start doing stupid things.
>> 
>> Cheers!
>> 
>> Bob
>> 
>> ----- Original Message ----
>> From: matt donovan <kitchetech at gmail.com>
>> To: nflug at nflug.org
>> Sent: Wednesday, February 21, 2007 12:55:54 PM
>> Subject: Re: [nflug] Daylight saviings time
>> 
>> if you use another distro just use ntpdate and you should be fine that's
>> how I m doing it.
>> 
>> On 2/15/07, Mark T. Valites < mark-nflug at valites.net> wrote:
>> >
>> > On Thu, 15 Feb 2007, anthonyriga wrote:
>> >
>> > > With the new DST enacted this year will that have any affect on Linux
>> > to
>> > > know the changes?
>> > >
>> > > Sent Using Ubuntu Linux Operating System Edgy 6.10
>> >
>> > Your Ubuntu 'tzdata' package already has the updated timezone info.
>> >
>> > For Redhat, this was taken care of with the following tzdata updates:
>> >
>> > tzdata-2005m-1.EL3 (http://rhn.redhat.com/errata/RHEA-2005-655.html)
>> > tzdata-2005m-1.EL4 (http://rhn.redhat.com/errata/RHEA-2005-656.html )
>> >
>> > which were issued shortly after the Energy Policy Act of 2005 that
>> > included these changes was passed.
>> >
>> > For Sun:
>> >
>> > http://sunsolve.sun.com/search/document.do?assetkey=1-26-102178-1
>> >
>> > I don't have the URL for Debian/Ubuntu offhand though.
>> > _______________________________________________
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>> > nflug at nflug.org
>> > http://www.nflug.org/mailman/listinfo/nflug
>> >
>> 
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>> 
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>

-- 
Mark T. Valites
Geeks Poster PITA
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