[COFF] Manipulating time_t values (was: Unix half-billion years old 1985)

[COFF] Manipulating time_t values (was: Unix half-billion years old 1985)

[grog]

[Moved to COFF]

On Monday,  4 November 2019 at 16:59:22 -0500, John P. Linderman wrote:
> I wrote a near-trivial "timestamp" command to make it easier to do time
> arithmetic
>
> TZ=udt timestamp
> 119 11 04 21 50 06 18204 1572904206 Mon Nov  4 21:50:06 2019
> TZ=udt timestamp 0
> 70 01 01 00 00 00 0 0 Thu Jan  1 00:00:00 1970
> ...

FreeBSD has this functionality in date(1):

 TZ=UTC date -r 500000000
 Tue  5 Nov 1985 00:53:20 UTC
 TZ=UTC date -r 1500000000
 Fri 14 Jul 2017 02:40:00 UTC

Greg
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[COFF] Manipulating time_t values (was: Unix half-billion years old 1985)

[bakul]

On Tue, 05 Nov 2019 10:00:55 +1100 Greg 'groggy' Lehey <grog at lemis.com> wrote:
>
> [Moved to COFF]
>
> On Monday,  4 November 2019 at 16:59:22 -0500, John P. Linderman wrote:
> > I wrote a near-trivial "timestamp" command to make it easier to do time
> > arithmetic
> >
> > TZ=udt timestamp
> > 119 11 04 21 50 06 18204 1572904206 Mon Nov  4 21:50:06 2019
> > TZ=udt timestamp 0
> > 70 01 01 00 00 00 0 0 Thu Jan  1 00:00:00 1970
> > ...
>
> FreeBSD has this functionality in date(1):
>
>  TZ=UTC date -r 500000000
>  Tue  5 Nov 1985 00:53:20 UTC
>  TZ=UTC date -r 1500000000
>  Fri 14 Jul 2017 02:40:00 UTC

Shouldn't that be 
    Tue  5 Nov 1985 00:52:57 UTC
    Fri 14 Jul 2017 02:39:23 UTC
given that this is UTC (which is 37 seconds behind TAI)?

Sorry :-)

[COFF] Manipulating time_t values (was: Unix half-billion years old 1985)

[imp]

On Mon, Nov 4, 2019, 5:00 PM Bakul Shah <bakul at bitblocks.com> wrote:

> On Tue, 05 Nov 2019 10:00:55 +1100 Greg 'groggy' Lehey <grog at lemis.com>
> wrote:
> >
> > [Moved to COFF]
> >
> > On Monday,  4 November 2019 at 16:59:22 -0500, John P. Linderman wrote:
> > > I wrote a near-trivial "timestamp" command to make it easier to do time
> > > arithmetic
> > >
> > > TZ=udt timestamp
> > > 119 11 04 21 50 06 18204 1572904206 Mon Nov  4 21:50:06 2019
> > > TZ=udt timestamp 0
> > > 70 01 01 00 00 00 0 0 Thu Jan  1 00:00:00 1970
> > > ...
> >
> > FreeBSD has this functionality in date(1):
> >
> >  TZ=UTC date -r 500000000
> >  Tue  5 Nov 1985 00:53:20 UTC
> >  TZ=UTC date -r 1500000000
> >  Fri 14 Jul 2017 02:40:00 UTC
>
> Shouldn't that be
>     Tue  5 Nov 1985 00:52:57 UTC
>     Fri 14 Jul 2017 02:39:23 UTC
> given that this is UTC (which is 37 seconds behind TAI)?
>

The delta was closer to 18 in 1985 and 36 on 2017. But that doesn't matter.

Sorry :-)
>

No. POSIX says leap seconds do not exist for the computation of these
numbers. Greg's numbers are POSIXly correct.

Warner

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[COFF] Manipulating time_t values (was: Unix half-billion years old 1985)

[dot]

Fans of time_t numerology might like my silly palindromic twitter bots,

https://twitter.com/time_t_emit
https://twitter.com/time_x_emit
https://twitter.com/time_o_emit
https://twitter.com/time_b_emit

Tony.
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