Is Daylight Savings enabled ?

kejoseph@hotmail.com writes:


>I have Redhat Linux Enterprise AS 3.3 and 4.x.

>I need to know whether Daylight Savings Time is enabled on my server. I
>simply cannot figure out where this setting is. If anyone knows where
>this setting is please let me know.

?? It isn't. the display of date and time are controlled by a file called
/etc/localtime
which is a copy of a tz database timezone file. It tells the ssytem exactly
when and for what dates that location used what time (as related to UTC)
Your system itself uses UTC in all its clocks. the localtime file controls
the display, not what goes on inside.
If you want a different timezone, copy in a different file
(/usr/share/zoninfo) into /etc/localtime.

Your system will immediately display the new timezone.
There is no "daylight saving flag"

Note that this will display the correct official time for your locality
even for dates in the past (eg your location may have decided to use
Zambian time for two months in 1922. The timezone file will contain that
and when you ask for a time during those two months you will get the
correct local time.)



>Ideally, I would like to know how to enable/disable it too.

>I have tried timeconfig but that does not provide any option.

>Kevin.

"Chris F.A. Johnson" <cfajohnson@gmail.com> writes:

>On 2006-04-04, kejoseph@hotmail.com wrote:
>>
>> I have Redhat Linux Enterprise AS 3.3 and 4.x.
>>
>> I need to know whether Daylight Savings Time is enabled on my
>server.

> At a command prompt, type 'date'. If the result shows DST you have
> been successfully changed; if not, you havent't.

well, no. That depends. Some places do NOT use a separate designator for
daylight as opposed to standard time. It depends entirely on your
particular location.



>> I simply cannot figure out where this setting is. If anyone knows
>> where this setting is please let me know.

> The system time should always be UTC (GMT). Your local setting is
> in /etc/localtime, and/or in the variable TZ.


>--
> Chris F.A. Johnson, author | <http://cfaj.freeshell.org>
> Shell Scripting Recipes: | My code in this post, if any,
> A Problem-Solution Approach | is released under the
> 2005, Apress | GNU General Public Licence

Jean-David Beyer <jeandavid8@verizon.net> writes:

>Michael Heiming wrote:
>> In comp.os.linux.misc kejoseph@hotmail.com:
>>
>>> I have Redhat Linux Enterprise AS 3.3 and 4.x.
>>
>>> I need to know whether Daylight Savings Time is enabled on my server. I
>>> simply cannot figure out where this setting is. If anyone knows where
>>> this setting is please let me know.
>>
>> Check "/etc/sysconfig/clock".
>>
>On my RHEL3 system, I get:

>[/etc/sysconfig]$ cat clock
>ZONE="America/New_York"
>UTC=true
>ARC=false

>It manages Daylight Savings Time correctly, but how do you tell from this?

Because New York impliments daylight saving time.

Jean-David Beyer <jeandavid8@verizon.net> writes:

>Robert Heller wrote:
>> kejoseph@hotmail.com,
>> In a message on 3 Apr 2006 23:22:47 -0700, wrote :
>>
>> k> I have Redhat Linux Enterprise AS 3.3 and 4.x.
>> k>
>> k> I need to know whether Daylight Savings Time is enabled on my server. I
>> k> simply cannot figure out where this setting is. If anyone knows where
>> k> this setting is please let me know.
>> k>
>> k> Ideally, I would like to know how to enable/disable it too.
>> k>
>> k> I have tried timeconfig but that does not provide any option.
>>
>> If you have selected a time zone where DST happens (such as any North
>> American time zone, except a few here and there, like Eire, Indiana),
>> it is set up automagically -- it is not something you turn on or off.
>> The few places that don't observe DST have their own special time
>> zones. If your machine runs *only* Linux (it not a dual boot
>> Linux/MS-Windows), you can set the hardware clock to Universal Standard
>> Time, and you won't have to worry about random 1 hour clock drift due
>> to a crash/reboot across a DST boundary.
>>
>What if you are running a server and some users log in from across a time
>zone boundary? Will they see the time where the server is located? I suppose so.

If they are running on the server, they will see the server's notion of
time. Of course.

On 2006-04-04, Unruh wrote:
> "Chris F.A. Johnson" <cfajohnson@gmail.com> writes:
>
>>On 2006-04-04, kejoseph@hotmail.com wrote:
>>>
>>> I have Redhat Linux Enterprise AS 3.3 and 4.x.
>>>
>>> I need to know whether Daylight Savings Time is enabled on my
>>server.
>
>> At a command prompt, type 'date'. If the result shows DST you have
>> been successfully changed; if not, you havent't.
>
> well, no. That depends. Some places do NOT use a separate designator for
> daylight as opposed to standard time. It depends entirely on your
> particular location.

Whether there's a designator or not is irrelevant. If it shows 1pm
it's standard time, if it's 2pm it's daylight saving time (replace
1 and 2 with appropriate hours).

--
Chris F.A. Johnson, author | <http://cfaj.freeshell.org>
Shell Scripting Recipes: | My code in this post, if any,
A Problem-Solution Approach | is released under the
2005, Apress | GNU General Public Licence

Jean-David Beyer <jeandavid8@verizon.net>,
In a message on Tue, 04 Apr 2006 13:07:16 GMT, wrote :

JB> Robert Heller wrote:
JB> > kejoseph@hotmail.com,
JB> > In a message on 3 Apr 2006 23:22:47 -0700, wrote :
JB> >
JB> > k> I have Redhat Linux Enterprise AS 3.3 and 4.x.
JB> > k>
JB> > k> I need to know whether Daylight Savings Time is enabled on my server. I
JB> > k> simply cannot figure out where this setting is. If anyone knows where
JB> > k> this setting is please let me know.
JB> > k>
JB> > k> Ideally, I would like to know how to enable/disable it too.
JB> > k>
JB> > k> I have tried timeconfig but that does not provide any option.
JB> >
JB> > If you have selected a time zone where DST happens (such as any North
JB> > American time zone, except a few here and there, like Eire, Indiana),
JB> > it is set up automagically -- it is not something you turn on or off.
JB> > The few places that don't observe DST have their own special time
JB> > zones. If your machine runs *only* Linux (it not a dual boot
JB> > Linux/MS-Windows), you can set the hardware clock to Universal Standard
JB> > Time, and you won't have to worry about random 1 hour clock drift due
JB> > to a crash/reboot across a DST boundary.
JB> >
JB> What if you are running a server and some users log in from across a time
JB> zone boundary? Will they see the time where the server is located? I suppose so.

Yes, unless that user sets the TZ environment variable in their login.

JB>
JB> --
JB> .~. Jean-David Beyer Registered Linux User 85642.
JB> /V\ PGP-Key: 9A2FC99A Registered Machine 241939.
JB> /( )\ Shrewsbury, New Jersey http://counter.li.org
JB> ^^-^^ 09:05:01 up 19 days, 9:18, 4 users, load average: 4.18, 4.13, 4.09
JB>

Robert Heller -- 978-544-6933
Deepwoods Software -- Linux Installation and Administration
http://www.deepsoft.com/ -- Web Hosting, with CGI and Database
heller@deepsoft.com -- Contract Programming: C/C++, Tcl/Tk

Bill Unruh writes:
> If they are running on the server, they will see the server's notion of
> time. Of course.

Adjusted for their zone if they have TZ set.
--
John Hasler
john@dhh.gt.org
Dancing Horse Hill
Elmwood, WI USA

In comp.os.linux.misc, on Tue 04 April 2006 08:02, Chris F.A. Johnson
<cfajohnson@gmail.com> wrote:

> At a command prompt, type 'date'. If the result shows DST you have
> been successfully changed; if not, you havent't.
>
robert@fabian:~> date
Tue Apr 4 18:13:14 BST 2006


Does that mean that I am not using daylight savings time? You could have
fooled me, I always thought that British Summer Time *was* our daylight
saving time. Are you saying that GMT (the time system we use in winter)
is in fact the DST?
--
Robert HULL

Archival or publication of this article on any part of thisishull.net
is without consent and is in direct breach of the Data Protection Act

Unruh <unruh-spam@physics.ubc.ca> writes:

>Jean-David Beyer <jeandavid8@verizon.net> writes:

>>Robert Heller wrote:
>>> kejoseph@hotmail.com,
>>> In a message on 3 Apr 2006 23:22:47 -0700, wrote :
>>>
>>> k> I have Redhat Linux Enterprise AS 3.3 and 4.x.
>>> k>
>>> k> I need to know whether Daylight Savings Time is enabled on my server. I
>>> k> simply cannot figure out where this setting is. If anyone knows where
>>> k> this setting is please let me know.
>>> k>
>>> k> Ideally, I would like to know how to enable/disable it too.
>>> k>
>>> k> I have tried timeconfig but that does not provide any option.
>>>
>>> If you have selected a time zone where DST happens (such as any North
>>> American time zone, except a few here and there, like Eire, Indiana),
>>> it is set up automagically -- it is not something you turn on or off.
>>> The few places that don't observe DST have their own special time
>>> zones. If your machine runs *only* Linux (it not a dual boot
>>> Linux/MS-Windows), you can set the hardware clock to Universal Standard
>>> Time, and you won't have to worry about random 1 hour clock drift due
>>> to a crash/reboot across a DST boundary.
>>>
>>What if you are running a server and some users log in from across a time
>>zone boundary? Will they see the time where the server is located? I suppose so.

>If they are running on the server, they will see the server's notion of
>time. Of course.
(except "of course" ,as Hassler says, I was too hasty. If the usr sets his TZ variable then on
most systems that entry will be looked up in /usr/share/zoneinfo, and the
filename in the TZ variable will be used for all of that user's time
translations rather than /etc/localtime. Ie, instead of /etc/localtime, it
will use /usr/share/zoneinfo/$TZ to translate the time.
If that file does not exist, it will use UTC. If TZ is undefined it will use
/etc/localtime.

So if the user logs in from New York on a server in Brussles, he can get
the system to interpret all times as New York times by having
export TZ=America/New_York
in his .bashrc file.


_

On 2006-04-04, Robert Hull wrote:
> In comp.os.linux.misc, on Tue 04 April 2006 08:02, Chris F.A. Johnson
><cfajohnson@gmail.com> wrote:
>
>> At a command prompt, type 'date'. If the result shows DST you have
>> been successfully changed; if not, you havent't.
>>
> robert@fabian:~> date
> Tue Apr 4 18:13:14 BST 2006
>
>
> Does that mean that I am not using daylight savings time?

You tell me. Is the time shown correct for daylight savings time or
not? Does BST stand for British Summer Time or British Standard
Time?

> You could have fooled me,

I doubt it.

> I always thought that British Summer Time *was* our daylight saving
> time.

So I would assume.

> Are you saying that GMT (the time system we use in winter) is in
> fact the DST?

Where did I say that?

--
Chris F.A. Johnson, author | <http://cfaj.freeshell.org>
Shell Scripting Recipes: | My code in this post, if any,
A Problem-Solution Approach | is released under the
2005, Apress | GNU General Public Licence