[comp.unix.sysv386] Daylight Savings Time..

bill@bilver.uucp (Bill Vermillion) (04/06/91)

In article <1991Apr5.173841.28805@ttank.ttank.com> karl@ttank.com writes:
>I've heard rumors that Congress is goign to push the daylight savings
>time ending back to the end of April.  Anyone have good ideas on how
>to tell SCO Xenix 2.3.3 this?  If all else fails I guess I'll reset TZ
>with a lie for a few weeks.

The problem we used to have was the system always thought daylight
savings time ended & started at the same time - eg x week of year
start, y week of the year end.

Well with the Carter adminstration energy conservation schemes,
time changes became unpredictable.  Many systems now are able to
take care of any changes that you wish, or that congress wishes
:-).

Look at TZ in the manual. You will see that start end of daylight
time can be set in one of three ways by using the script /etc/tz.

By week of the year (1-52), Week of a month ( eg 1st week of Apri)
or day of the year (1-365).

If you tell the script you are not in the US you can set the
letters you want for regular time and summertime, and how many
hours, minutes, and seconds you are west of GMT or a negative
amount if you are east.  You can also set the time of day that
conversion from one to the other occurs.

In other words, we don't have to worry about the laws changing
because we can handle it ourselves.

-- 
Bill Vermillion - UUCP: uunet!tarpit!bilver!bill
                      : bill@bilver.UUCP

kreed@telesys.cts.com (Kevin W. Reed) (04/07/91)

[Followup to comp.unix.xenix.sco]

tts@ttank.ttank.com (Karl Bunch) writes:
>I've heard rumors that Congress is goign to push the daylight savings
>time ending back to the end of April.  Anyone have good ideas on how
>to tell SCO Xenix 2.3.3 this?  If all else fails I guess I'll reset TZ
>with a lie for a few weeks.

The controlling factor for when DST goes into and out of effect is located
in the file /etc/tz (SCO Xenix), Unix and others might be different??.

Mine is set up as:

	TZ=PST08:00:00PDT07:00:00;M4.1.0/02:00:00,M10.5.0/02:00:00

Which breaks down to:

	Difference in time from GMT when PST	PST08:00:00
	Difference in time from GMT when PDT	PDT07:00:00
	Month the change to PDT and when	M4.1.0/02:00:00
		(April First Week Sunday)
	Month the change to PST and when	M10.5.0/02:00:00
		(Oct Fifth Week Sunday)

I found this information in the man pages tz(M).

If congress changes the start and or end, all you need to do is change
this string to match what the change is.  If it is moving to end of
April then:

	TZ=PST08:00:00PDT07:00:00;M4.5.0/02:00:00,M10.5.0/02:00:00

>Karl
>-- 
>% ----------------------------------------------------------------------------
>% Karl Bunch                            ||| UUCP: ..!uunet!zardoz!ttank!karl
>% Think Tank Software                   ||| INTERNET: karl@ttank.com
>% ".you'd be suprised how far a hug will go with Geordi, even Worf!" -- Riker

-- 
Kevin W. Reed      TeleSys Development Systems   San Diego, CA USA
{nosc,ucsd}!crash!telesys!kreed              kreed@telesys.cts.com
TeleSys-II BBS & Development System Primary Number +1 619 483 3890