[SLE] PDT/PST Timezones?

[Chris Carlen]

Hi:

I am in Pacific timezone, but I don't know when it is supposed to be PST
vs. PDT. I have a NTP client running, and my clocks are:


ngong:/home/user1 # date
Thu May 5 14:44:23 PDT 2005
ngong:/home/user1 # hwclock
Thu 05 May 2005 01:44:26 PM PDT -0.461233 seconds


Is PDT correct for this time of year? Is this set automagically?


Thanks for input.

Good day!
--
_____________________
Christopher R. Carlen
***@bogus-remove-me.sbcglobal.net
SuSE 9.1 Linux 2.6.5

[James D. Parra]

Post by Chris Carlen
Is PDT correct for this time of year? Is this set automagically?

Pacific Daylight (Savings) Time, PDT is correct. You'll use PST, Pacific
Standard Time, in the winter. This was set for you when you selected your
TimeZone, for example, Los Angeles.

http://www.timeanddate.com/worldclock/city.html?n=137

~James

[James Knott]

Post by Chris Carlen
I am in Pacific timezone, but I don't know when it is supposed to be PST
ngong:/home/user1 # date
Thu May 5 14:44:23 PDT 2005
ngong:/home/user1 # hwclock
Thu 05 May 2005 01:44:26 PM PDT -0.461233 seconds
Is PDT correct for this time of year? Is this set automagically?

It would be PDT. The time changes in April & October. If your computer
is set up correctly, it should change automatically.

[Randall R Schulz]

James,

Post by James Knott

Post by Chris Carlen
I am in Pacific timezone, but I don't know when it is supposed to
be PST vs. PDT. ...
...
Is PDT correct for this time of year? Is this set automagically?

It would be PDT. The time changes in April & October. If your
computer is set up correctly, it should change automatically.

My experience with recent OSes, including all of MacOS, Windows and
Linux, is that they automatically adapt to the onset and termination of
Daylight Saving Time (even my VCR does this, based on time signals
embedded in TV broadcasts).

My question is, how is this handled in Linux? Is it part of the NTP
protocol, or must the dates be encoded in some configuration
information somewhere? If it's the latter, how will the possible
legislative change to the national DST start and end dates be
accommodated in Linux software?


Randall Schulz

[Jerry Feldman]

Post by Chris Carlen
I am in Pacific timezone, but I don't know when it is supposed to be PST
ngong:/home/user1 # date
Thu May 5 14:44:23 PDT 2005
ngong:/home/user1 # hwclock
Thu 05 May 2005 01:44:26 PM PDT -0.461233 seconds
Is PDT correct for this time of year? Is this set automagically?

There are 2 answers:
1. If you set your system clock to UCT (which is the preferred method), your
time will update correctly even without using ntp as long as you don't have
much drift.

2. If you set your system clock to local time (because you dual boot with
Windows) I have found that without ntp, Linux does not update to daylight
time in April and revert in October.

However, if you use ntp (as you mentioned) then your clocks should be kept
in sync.
The only place where this does not work is in Indiana because they can't
figure out what timezone they want to be in.
(Parts of Indiana are in Eastern and do not adjust for DST, other parts are
in Eastern and do adjust for DST, and parts are in Central and those do
adjust. recently the Indiana legislature voted to use DST for the whole
state, but part of the state will still; be Central while the rest will be
Eastern.

http://www.timetemperature.com/tzus/indiana_time_zone.shtml
--
Jerry Feldman <***@blu.org>
Boston Linux and Unix user group
http://www.blu.org PGP key id:C5061EA9
PGP Key fingerprint:053C 73EC 3AC1 5C44 3E14 9245 FB00 3ED5 C506 1EA9

[James Knott]

Post by Jerry Feldman
The only place where this does not work is in Indiana because they can't
figure out what timezone they want to be in.
(Parts of Indiana are in Eastern and do not adjust for DST, other parts are
in Eastern and do adjust for DST, and parts are in Central and those do
adjust. recently the Indiana legislature voted to use DST for the whole
state, but part of the state will still; be Central while the rest will be
Eastern.
http://www.timetemperature.com/tzus/indiana_time_zone.shtml

It's amazing how a country as technologically advanced as the U.S. can
be so backward in so many things.

Incidentally, at one time many farmers were against DST, as they claimed
the "extra hour" of sunlight would burn crops. It appears that sort of
thinking still exists.

Some religious groups express similar backward ideas.

[Randall R Schulz]

James,

Post by James Knott
...
Incidentally, at one time many farmers were against DST, as they
claimed the "extra hour" of sunlight would burn crops. ...

I challenge you to produce documentation of such a claim ever having
been made during the debate over daylight savings time.

Post by James Knott
...

Randall Schulz

[James Knott]

Post by Randall R Schulz
James,

Post by James Knott
...
Incidentally, at one time many farmers were against DST, as they
claimed the "extra hour" of sunlight would burn crops. ...

I challenge you to produce documentation of such a claim ever having
been made during the debate over daylight savings time.

<http://www.ojaivalleynews.com/issues2003/04-April2003/04-11-03/04-11-03editorials.html>

" Our first bout with Daylight Stolen Time was during World War I, and
it was quickly repealed after war's end. One Wisconsin legislator
actually got on the floor of Congress and, in his testimony, pronounced
against DST on the grounds that the extra hour of sunlight would burn
the crops. Perhaps, in a delusion common to this nation's lawmakers, he
actually thought that ordering the duration of the day was among the
prerogatives of office. More power to him, then, that he chose to refuse
to wield that authority."

[Randall R Schulz]

James,

Post by James Knott

Post by Randall R Schulz
James,

Post by James Knott
...
Incidentally, at one time many farmers were against DST, as they
claimed the "extra hour" of sunlight would burn crops. ...

I challenge you to produce documentation of such a claim ever
having been made during the debate over daylight savings time.

<http://www.ojaivalleynews.com/issues2003/04-April2003/04-11-03/04-11
-03editorials.html>
" Our first bout with Daylight Stolen Time was during World War I,
and it was quickly repealed after war's end. One Wisconsin legislator
actually got on the floor of Congress and, in his testimony,
pronounced against DST on the grounds that the extra hour of sunlight
would burn the crops. Perhaps, in a delusion common to this nation's
lawmakers, he actually thought that ordering the duration of the day
was among the prerogatives of office. More power to him, then, that
he chose to refuse to wield that authority."

You said farmers believed this. You've only produced a claim that a
legislator made such a statement.

It's sad that my state (I'm from Wisconsin) has produced this (alleged)
moron along with that despot Joseph McCarthy (a senator, no less).

I guess you have to take the good with the bad.

Randall Schulz

[Ken Schneider]

Post by Randall R Schulz
James,

Post by James Knott
...
Incidentally, at one time many farmers were against DST, as they
claimed the "extra hour" of sunlight would burn crops. ...

I challenge you to produce documentation of such a claim ever having
been made during the debate over daylight savings time.

I was a youngster when DST was going into affect and remember the same
type of thing going on, the the farmers thought the "extra" hour of
daylight would create problems.
--
Ken Schneider
UNIX since 1989, linux since 1994, SuSE since 1998

"The day Microsoft makes something that doesn't suck is probably
the day they start making vacuum cleaners." -Ernst Jan Plugge

[Randall R Schulz]

Ken,

Post by Ken Schneider

Post by Randall R Schulz
James,

Post by James Knott
...
Incidentally, at one time many farmers were against DST, as they
claimed the "extra hour" of sunlight would burn crops. ...

I challenge you to produce documentation of such a claim ever
having been made during the debate over daylight savings time.

I was a youngster when DST was going into affect and remember the
same type of thing going on, the the farmers thought the "extra" hour
of daylight would create problems.

"Creating problems" does not equate with believing that DST would "burn
the crops" (let alone believing the day would be lengthened).

I certainly hope these statements do not reflect an attitude about the
intelligence typical of farmers, either today or a hundred years ago.

Post by Ken Schneider
Ken Schneider

Randall Schulz

[James Knott]

Post by Randall R Schulz
Ken,

Post by Ken Schneider

Post by Randall R Schulz
James,

Post by James Knott
...
Incidentally, at one time many farmers were against DST, as they
claimed the "extra hour" of sunlight would burn crops. ...

I challenge you to produce documentation of such a claim ever
having been made during the debate over daylight savings time.

I was a youngster when DST was going into affect and remember the
same type of thing going on, the the farmers thought the "extra" hour
of daylight would create problems.

"Creating problems" does not equate with believing that DST would "burn
the crops" (let alone believing the day would be lengthened).
I certainly hope these statements do not reflect an attitude about the
intelligence typical of farmers, either today or a hundred years ago.

One thing I've noticed, is that many people will blindly accept an idea
that "makes sense", even though if they gave it some thought, they'd
realize it's nonsense. Religion is the greatest example of this. You
might want to read Carl Sagan's "A Demon Haunted World" or "Voodoo
Science", by Robert Park, for some examples of the nonsense many people
believe. Or check out the supermarket rags. One thing that's
apparently in very short supply, is critical thinking.

[Jerry Feldman]

On Sat, 07 May 2005 07:03:12 -0400

Post by James Knott
One thing that's
apparently in very short supply, is critical thinking.

And this is just the sort of thing that has squared scientists off
against religionists. let's go back a few thousands of years. A guy
decided that pantheistic idol worship made no sense but he also felt
that there was some divine hand behind the world, and at that moment,
Abraham became the father of Judaism, Christianity and Islam.
Copernicus measured the orbits of the planets and proved the planets
revolve around the sun. Many who believed that went to jail for their
critical thinking.

[Jerry Feldman]

Post by James Knott

Post by Jerry Feldman
The only place where this does not work is in Indiana because they
can't figure out what timezone they want to be in.
(Parts of Indiana are in Eastern and do not adjust for DST, other parts
are in Eastern and do adjust for DST, and parts are in Central and
those do adjust. recently the Indiana legislature voted to use DST for
the whole state, but part of the state will still; be Central while the
rest will be Eastern.
http://www.timetemperature.com/tzus/indiana_time_zone.shtml

It's amazing how a country as technologically advanced as the U.S. can
be so backward in so many things.
Incidentally, at one time many farmers were against DST, as they claimed
the "extra hour" of sunlight would burn crops. It appears that sort of
thinking still exists.
Some religious groups express similar backward ideas.

There are many urban legends. Other than Indiana, Arizona and Hawaii do not
use Daylight time.
Good history here. Some of the complaints are included below.
"The idea of daylight saving was first conceived by Benjamin Franklin
(portrait at right) during his sojourn as an American delegate in Paris in
1784"
http://webexhibits.org/daylightsaving/
Another complaint is sometimes put forth by people who wake at dawn, or
whose schedules are otherwise tied to sunrise, such as farmers. Farmers
often dislike the clocks changing mid year. Canadian poultry producer Marty
Notenbomer notes, "The chickens do not adapt to the changed clock until
several weeks have gone by so the first week of April and the last week of
October are very frustrating for us."

In Israel, ultra-Orthodox Sephardic Jews have campaigned against daylight
saving time because they recite Slikhot penitential prayers in the early
morning hours during the Jewish month of Elul.

A writer in 1947 wrote, "I don't really care how time is reckoned so long as
there is some agreement about it, but I object to being told that I am
saving daylight when my reason tells me that I am doing nothing of the
kind. I even object to the implication that I am wasting something valuable
if I stay in bed after the sun has risen. As an admirer of moonlight I
resent the bossy insistence of those who want to reduce my time for
enjoying it. At the back of the Daylight Saving scheme I detect the bony,
blue-fingered hand of Puritanism, eager to push people into bed earlier,
and get them up earlier, to make them healthy, wealthy and wise in spite of
themselves." (Robertson Davies, The Diary of Samuel Marchbanks, 1947, XIX,
Sunday.)
--
Jerry Feldman <***@blu.org>
Boston Linux and Unix user group
http://www.blu.org PGP key id:C5061EA9
PGP Key fingerprint:053C 73EC 3AC1 5C44 3E14 9245 FB00 3ED5 C506 1EA9

[Carlos E. R.]

Post by Jerry Feldman
A writer in 1947 wrote, "I don't really care how time is reckoned so long as
there is some agreement about it, but I object to being told that I am
saving daylight when my reason tells me that I am doing nothing of the
kind. I even object to the implication that I am wasting something valuable
if I stay in bed after the sun has risen. As an admirer of moonlight I
resent the bossy insistence of those who want to reduce my time for
enjoying it. At the back of the Daylight Saving scheme I detect the bony,
blue-fingered hand of Puritanism, eager to push people into bed earlier,
and get them up earlier, to make them healthy, wealthy and wise in spite of
themselves." (Robertson Davies, The Diary of Samuel Marchbanks, 1947, XIX,
Sunday.)

I couldn't agree more. For me, time reference should be a stable and
unchangeable thing. I don't care which one, as long as it doesn't ever
change.

[rant start]

I still can't believe energy can be saved that way. And it is a 4*x
nuisance, having to go round all the house adjusting every watch and
clock: alarm clocks, heating, microwave, car, radio, kitchen, siting room,
all sort of gadgets... I hate it. Then being hungry at the "wrong" hour.

And, of course, just be careful you don't happen to travel that day: here
trains stop at 3:00 for an hour till it is again 3:00 - or was it 2:00? At
the other end of the year, they just are one hour late, and you loose your
connections.

Savings? Who saves? Not me. :-/

[enough ranting...]

[Carlos E. R.]

Post by Jerry Feldman

Post by Chris Carlen
Is PDT correct for this time of year? Is this set automagically?

1. If you set your system clock to UCT (which is the preferred method), your
time will update correctly even without using ntp as long as you don't have
much drift.
2. If you set your system clock to local time (because you dual boot with
Windows) I have found that without ntp, Linux does not update to daylight
time in April and revert in October.

That's not correct. I have sat in front of my computer at the the exact
moment that the daylight change should occur, and it does, correctly and
smoothly. I don't have an ntp daemon, and I was not connected to the
network at that moment.

Notice that internally, Linux always keeps UTC (not UCT), regardless of
timezone settings. In fact, each user on the same machine may have a
different time setting. The system is very simple: as UTC doesn't change,
local time is calculated and daylight saving time applied appropriately,
from the internal UTC, and printed for the user to see. For this, of
course, the programmers must know how to calculate it in advance.

Try it:

***@nimrodel:~> TZ=UTC date
Mon May 9 02:01:09 UTC 2005
***@nimrodel:~> date
Mon May 9 04:01:13 CEST 2005
***@nimrodel:~> TZ=PST date
Mon May 9 02:02:39 PST 2005
***@nimrodel:~> TZ=PDT date
Mon May 9 02:02:46 PDT 2005
***@nimrodel:~>

You can get any time on the fly - just by setting the TZ variable.


Notice also that when in Yast you use that configuration box that says
"use local time" it only means that the CMOS clock (which is not the
system time, but the battery cmos chip that keeps time with the computer
off) keeps local time instead of UTC. It does not mean that system time
will be local or UTC time: system time will always be UTC.
--
Cheers,
Carlos Robinson