[tz] Version identification (was Re: Downstream use of 2021c)

[Deborah Goldsmith]

FYI, 2021a.1.0 just refers to 2021a. Apple released what ICU called 2021a1 as 2021a.2.0. The +VERSION file for that is still 2021a.

You probably already have 2021a.2.0 downloaded; you can check via:

% ls -l /var/db/timezone

If so, rebooting will make it the active version of tzdb.

See this page for an overview:
https://support.apple.com/en-us/HT206986 

Deborah

> On Oct 7, 2021, at 1:00 PM, Tom Lane via tz <tz at iana.org> wrote:
> 
> Guy Harris <gharris at sonic.net> writes:
>> On Oct 7, 2021, at 10:00 AM, Tom Lane via tz <tz at iana.org> wrote:
>>> I'm envisioning that there could be a text file at the top level,
>>> say /usr/share/zoneinfo/version in typical layouts, containing
>>> "2021a" or the appropriate string.  This'd make it a lot easier
>>> to diagnose what you've got in a particular installation.
> 
>> $ cat /usr/share/zoneinfo/+VERSION
>> 2021a
> 
> Interesting ... and in fact, Apple's labeling it in another way too,
> because I see this on my Mac laptop:
> 
> $ ls -l /usr/share/zoneinfo/
> lrwxr-xr-x  1 root  wheel  38 Sep 13 19:15 /usr/share/zoneinfo/ -> /var/db/timezone/tz/2021a.1.0/zoneinfo
> 
> But that pretty much just begs the point, which is that there's
> no *standard* cross-platform way to get this info.  On my RHEL
> workstation, I don't see any identification info except the
> first line of tzdata.zi, which isn't a standard inclusion either.
> (Of course, I can consult the RPM package database to find out the
> version of the tzdata package ... still more platform dependency.)
> 
> My point isn't whether it's possible to figure this out on any
> given platform, but that tzdata itself ought to define a standard
> way to find it out.  And I do not agree with Paul's opinion that
> "include tzdata.zi" is a good enough answer; lots of platforms
> won't care to expend the disk space to do it that way.
> 
> (But, in view of Apple having already done it like that, maybe
> there's something to be said for using +VERSION as the file name.)
> 
> 			regards, tom lane