GNU bug report logs - #6897
date -d '1991-04-14 +1 day' fails

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From: Paul Eggert <eggert <at> CS.UCLA.EDU>
To: Alan Curry <pacman-cu <at> kosh.dhis.org>
Cc: 6897 <at> debbugs.gnu.org, 李嘉鹏 <lijpbasin <at> 126.com>
Subject: bug#6897: date -d '1991-04-14 +1 day' fails
Date: Mon, 23 Aug 2010 09:01:39 -0700

On 08/22/10 18:09, Alan Curry wrote:
> There might be less occurrences of this misunderstanding if we could teach
> date that -d 4/14/1991 is not actually a request for 4/14/1991 00:00:00, but
> "any time that existed during the day 4/14/1991", or perhaps a more specific
> "the first second of 4/14/1991".
> 
> Has that been considered and rejected already, or is it just waiting for
> someone to implement it?

As far as I know nobody has ever suggested that, and it is a reasonable suggestion.
However, it would not fix the problem in general, since in some cases there
is no "first second of date X", even when X is valid.  For example:

$ TZ=Pacific/Kwajalein date -d 1993-08-20
date: invalid date `1993-08-20'

There was no time during the day 1993-08-20, because at midnight Kwajalein
moved the clocks ahead by 24 hours.

Perhaps the semantics could be "the first second whose time stamp is on
or after 1993-08-20 00:00:00", though then we'd have to deal with bug reports
from people on Kwajalein saying "wait a minute: I asked for August 20, but
it gave me August 21!".

Aren't dates fun?

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