Subject: Re: Snapshot Report - 27 March tar_files
To: Martin Husemann <martin@euterpe.owl.de>
From: Michael L. VanLoon -- Iowa State University <michaelv@iastate.edu>
List: current-users
Date: 03/29/1994 23:55:03
>> 3. I've seen lots of stuff about timezone's being a bit dodgy,
>> especially with most European timezones changing over to DST on the
>> 27th March. I must say that that was NOT the case for me - pumpy is
>> running off the /usr/share/zoneinfo/GB-Eire timezone file,
>> (symbolically) linked to /etc/localtime, the CMOS clock is running off
>> GMT, and the kernel is compiled with "timezone 0".
>I use /usr/share/zoneinfo/MET as /etc/localtime and have the kernel configured
>as
>
>timezone -1 dst 4
>
>(My wife is running DOS on this machine for doom sometimes ;-)
>
>I set this strange dst value after diging in some old ultrix(?) man pages.
>There were several dst-changing-method listed and 4 was the code for the
>central europe one.
This gave me an idea... I use an Ultrix box every day, so why not...
Now, I don't know how closely this applies to NetBSD since Ultrix is
based on a much older version of BSD, and this isn't for the kernel
config, but for an envar of timezone values, but it's at least
somewhat enlightening on possible meanings for these things. Could
someone in the know shed light on how accurately this models the
timezone stuff in the kernel config? When I did "man timezone" this
is what I got (portion of this quoted from the DEC MIPS Ultrix 4.3a
timezone(3) manpage, slightly hacked by me):
STD offset [DST [offset][,start[/time],end[/time]]]
the components of the string have the following meaning:
STD and DST Three or more characters that are the designation for the
standard (STD) or summer (DST) time zone. Only STD is
required; if DST is missing, then summer time does not
apply in this locale. Upper- and lowercase letters are
explicitly allowed. Any characters except a leading colon
(:), digits, comma (,), minus (-), plus (+), and ASCII
NUL are allowed.
offset Indicates the value to be added to the local time to
arrive at Coordinated Universal Time. The offset has the
form:
hh[:mm[:ss]]
The minutes (mm) and seconds (ss) are optional. The hour
(hh) is required and may be a single digit. The offset
following STD is required. If no offset follows DST, sum-
mer time is assumed to be one hour ahead of standard
time. One or more digits may be used; the value is always
interpreted as a decimal number. The hour must be
between zero and 24, and the minutes (and seconds) - if
present - between zero and 59. If preceded by a "-", the
time zone is east of the Prime Meridian; otherwise it is
west (which may be indicated by an optional preceding
"+").
start and end Indicates when to change to and back from summer time.
Start describes the date when the change from standard to
summer time occurs and end describes the date when the
change back happens. The format of start and end must be
one of the following:
Jn The Julian day n (1 < n < 365). Leap days are not
counted. That is, in all years, including leap
years, February 28 is day 59 and March 1 is day
60. It is impossible to explicitly refer to the
occasional February 29.
n The zero-based Julian day (0 < n < 365). Leap
days are counted, and it is possible to refer to
February 29.
Mm.n.d The nth d day of month m (1 < n < 5, 0 < d < 6, 1
< m < 12). When n is 5 it refers to the last d
day of month m. Day 0 is Sunday.
time The time field describes the time when, in current time,
the change to or from summer time occurs. Time has the
same format as offset except that no leading sign (a
minus sign (-) or a plus sign (+)) is allowed. The
default, if time is not given, is 02:00:00.
As an example of the previous format, if the TZ environment variable had
the value EST5EDT4,M4.1.0,M10.5.0 it would describe the rule, which went
into effect in 1987, for the Eastern time zone in the USA. Specifically,
EST would be the designation for standard time, which is 5 hours behind
GMT. EDT would be the designation for DST, which is 4 hours behind GMT.
DST starts on the first Sunday in April and ends on the last Sunday in
October. In both cases, since the time was not specified, the change to
and from DST would occur at the default time of 2:00 AM.
The timezone call remains for compatibility reasons only; it is impossi-
ble to reliably map timezone's arguments (zone, a `minutes west of GMT'
value and DST, a `daylight saving time in effect' flag) to a time zone
abbreviation.
[etc....]
-----------------------------------------------------------------------------
Michael L. VanLoon Iowa State University Computation Center
michaelv@iastate.edu Project Vincent Systems Staff
Free your mind and your machine -- NetBSD free Un*x for PC/Mac/Amiga/etc.
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