Re: difference in seconds between two formatted dates ...

[David Wright <deblis@lionunicorn.co.uk>]

On Sun 24 Dec 2023 at 23:05:53 (+0000), Albretch Mueller wrote:
> On 12/18/23, Max Nikulin <manikulin@gmail.com> wrote:
> > Timestamp format you have chosen is ambiguous.
> >
> > TZ=Europe/Berlin date -d '@1698539400' '+%Y%m%d%H%M%S'
> > 20231029023000
> >
> > TZ=Europe/Berlin date -d '@1698543000' '+%Y%m%d%H%M%S'
> > 20231029023000
> >
> > You had issues with setting time and timezone, so '+%s' may give
> > incorrect results.
> 
> Hmm! and one hour difference is not detected, because of the way is
> being parsed. Why would that happen?

Spring forward and fall back—the clocks change, skipping an hour in
spring and repeating an hour in autumn (Northern hemisphere).

> Why would %S be in the range
> second (00..60), instead of (00..59)?:

Leap seconds—see the example already in the thread:

  https://lists.debian.org/debian-user/2023/12/msg00976.html

> seks00=1698539400; TZ=Europe/Berlin date -d '@1698539400' '+%Y%m%d%H%M%S'
> 
> seks02=1698543000; TZ=Europe/Berlin date -d '@1698543000' '+%Y%m%d%H%M%S'
> 
> diff_seks=$(( seks02 - seks00 ))
> echo "// __ \$diff_seks: |$diff_seks|"
> 
> https://man7.org/linux/man-pages/man1/date.1.html
> %Y     year
> %m     month (01..12)
> %d     day of month (e.g., 01)
> %H     hour (00..23)
> %M     minute (00..59)
> %S     second (00..60)

Cheers,
David.