Re: difference in seconds between two formatted dates ...
On Sun, Dec 17, 2023 at 03:28:58PM +0000, Albretch Mueller wrote:
> On 12/17/23, tomas@tuxteam.de <tomas@tuxteam.de> wrote:
> > On Sun, Dec 17, 2023 at 10:12:11AM +0000, Albretch Mueller wrote:
> >> dt00=$(date +%Y%m%d%H%M%S)
> >> echo "// __ \$dt00: |${dt00}|"
> >>
> >> ... after some long processing for which seconds would be exact
> >> enough, then I would like to get the seconds elapsed since dt00, like
> >> this:
> >>
> >> dt02=$(date +%Y%m%d%H%M%S)
> >> echo "// __ \$dt02: |${dt02}|"
> >
> > [...]
> >> because bash Arithmetic is 10-based.
> >
> > You wouldn't expect bash to intuit such a crooky arithmetic as
> > Gregorian datetime (and then, based on what? The number beginning
> > with 2023? Sounds kind of exciting).
>
> Actually, my basic idea is if you can encode a date using formatting
> options this utility provides, then you should be able to decode it
> using the same options that same utility provides, no? ... and then
> get "seconds since 1970-01-01" which wouldn't matter when you are
> computing the difference between two 10-based whole numbers which can
> be represented exactly in binary Arithmetic.
>
> > If you could live with a datetime format which date can understand
> > (instead of your cobbled-up pseudo numeric monster above) ...
>
> Thank you. I learned something out of it, but I used such "cobbled-up
> pseudo numeric monster" because, in kind of a poor-man's "measured"
> way, I use size, line count, last mod and sha256 metadata in file
> names baselining the system's state. I avoid spaces and any other
> characters you can't use in most fs' and/or may be interpreted by
> shells or OSs in their own ways.
>
> > น Pedants at this point may feel the need to launch launch into a
> > sub-thread about how subtracting one epoch time from another doesn't
> > always produce an accurate duration. I can't stop you, but it won't
> > be news to me.
>
> No calendar issue here. All is needed is turning dates into seconds
> to get the time diff in seconds. I am not trying to start a
> sub-thread, but how on earth would that not always produce an accurate
> duration?
>
> lbrtchx
>
https://xkcd.com/2867/ refers,
Andy
(amacater@debian.org)
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