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Re: displaying Date using local timezone
From: |
Bob Carragher |
Subject: |
Re: displaying Date using local timezone |
Date: |
Mon, 03 May 2021 03:56:06 -0700 |
On Mon, 03 May 2021 09:30:46 +0100 Ralph Corderoy <ralph@inputplus.co.uk> sez:
> Hi Bob,
Hi Ralph,
This time you're not giving me happy-useful news. B-D
> > > $ TZ=Australia/Lord_Howe date -d '01 Aug'
> > > 2021-08-01 00:00:00 +1030 Sun
> > > $ TZ=Australia/Lord_Howe date -d '01 Feb'
> > > 2021-02-01 00:00:00 +1100 Mon
> >
> > Wat. -_-##
> >
> > Why?! I can see some localities deciding that having their time zone
> > not be an integer number of hours offset can be more representative or
> > useful for them
>
> Yes, India is +05:30 with no DST. And there are finer-grained ones,
> e.g.
>
> $ tz() { printf '%s %s\n' `TZ=$1 date +%z` $1; }
> $ for t in UTC Australia/Eucla; do tz $t; done
> +0000 UTC
> +0845 Australia/Eucla
> $
I had an inkling that it might be bad for NMH to try to handle
DST calculations on its own; hopefully it's not trying to do any
with time zones (but rather relying on system libraries that are
intended to figure out all that) ....
> Perhaps some known-to-fail tests could be added to nmh's test suite.
>
> > but why mess with the DST offset, too?
>
> In Lord Howe's case it's so its time agrees with the mainland half the
> time. Aussies.
More like "Humans." B-)
> Why bother with DST in the first place? Isn't it a relic of the
> pre-industrial era when farm labourers would rise by the sun to maximise
> work on the land?
Nope: it's a relic of the Industrial Age/WW1:
https://en.wikipedia.org/wiki/Daylight_saving_time
> I didn't bother adjusting one year, initially by accident, and given
> work was a bit flexible on hours it was quite simple to just adjust ‘my
> truth’ of time to local time for the odd appointment, TV programme
> schedule, etc. Isn't the sudden switch for those that must live by the
> state's clock meant to harm health?
There are indications that, at least on the Monday after each
switchover, certain problems see spikes, such as car crashes and
heart attacks. I personally wouldn't mind seeing DST eliminated.
> > At this rate, they might as well just create a server that calculates
> > the sun's position in the sky on a second-by-second basis and send out
> > that time accordingly for people to sync their computers to. -_-#
>
> That occurred to me on the last switch and Google suggested its been
> done by others. Though I think it might be better to produce a local
> time so my normal waking clock times are centred around the daylight.
> :-)
Well, that's what I meant: depending on your longitude, the
server would give you a "local time," perhaps centered around the
daylight. Though I also heard one proposal for just a universal
time (like UTC) that everyone uses (to avoid issues like "Is my
3pm your 10am or 11am?"), and you always do a conversion to
calculate your local time. Both of these seem to require
computing devices, making it hard or impossible for us old fogeys
who still use _actual_ clocks. B-)
> DST is generally odd. The Yanks mostly have DST. But not in Arizona.
> Except for Navajo Nation which is inside AZ. But there's no DST in Hopi
> Nation which is inside Navajo Nation.
>
> $ tz() { printf '%s %s\n' "`TZ=$1 date '+%z %Z'`" $1; }
> $ for t in America/{Phoenix,Shiprock}; do tz $t; done
> -0700 MST America/Phoenix
> -0600 MDT America/Shiprock
> $
>
> And if you carry on up the Wakhjir Pass in Afghanistan then the clocks
> will switch from +0430 to +0800 as you enter the People's Most
> Democratic Uncensorious Republic of China.
Like I said: "Humans." B-)
Bob