[tz] Looking for details on timezones “right/…”

Robert Elz kre at munnari.OZ.AU
Tue Jan 17 18:57:53 UTC 2023

    Date:        Sun, 15 Jan 2023 18:40:27 +0100
    From:        =?utf-8?Q?Jens_Tr=C3=B6ger?= via tz <tz at iana.org>
    Message-ID:  <2FB37B4F-3F85-4260-8C49-D770591075C6 at light-speed.de>

  | Today I stumbled upon timezone strings like “right/UTC”,

Many systems don't bother installing those, as they're not usually
very useful on POSIX systems.

  | I’m unable to find details on the meaning & classification of the
  | “right/” here and how it relates to actual UTC and other timezones.

The right/* zones convert genuine UTC (that is, the time that occasionally
steps 23:59:58 23:59:59 23:59:60 00:00:00 00:00:01) with leap seconds

That's not what you get in a posix time_t - there all days are 86400
seconds long, no matter what, so a year is always (365 or 366) * 86400

Only if you get (from somewhere) timestamps that are genuinely in UTC
and not the POSIX approximation of it you get from gettimeofday() or
clock_*() or stat(), ... are the right/* zones useful for anything at
all.   Unless you're an astronomer, or rocket engineer, the chances
of that aren't high.


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