[tz] tzselect from current local time

Paul Eggert eggert at cs.ucla.edu
Tue Jan 17 21:42:03 UTC 2023

On 1/17/23 00:31, Robert Elz wrote:

> the more common usage would seem to be when
> installing a system, where nothing can be assumed about the
> system's clock at all

My impression is that during installation most systems nowadays get UTC 
from NTP, and do not ask the user for the current time. By the time 
these installations ask for a timezone, UTC is already known.

It's been many years since an install asked me for the current time. No 
doubt things work differently on non-networked installations, but 
increasingly these are done only in specialized environments where 
installers are assumed to be somewhat expert anyway, so I'm not as 
worried about them.
> So I'd suggest (if this method is to be retained) that it come
> with a warning that it only be used if the system's UTC clock
> is already correctly set, which I do not know of any way to
> verify that can be expected to work during system installation
> (no network yet operating).

Yes, I don't know any way either.

Thanks for the suggestion. tzselect already warns to some extent, as it 
asks you to confirm both local time and UTC. However, tzselect can do 
better by rewording its earlier questions so that it asks for the 
relation between local time and UTC, not for the current local time. 
That way, even if the platform's UTC clock is wrong the questions and 
answers still make sense. I installed the attached proposed patch to try 
to do that.
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