GNU bug report logs - #20199
Enhancement request for date's "-d" option: different epochs

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Message #8 received at 20199 <at> debbugs.gnu.org (full text, mbox):

From: Pádraig Brady <P <at> draigBrady.com>
To: Ulrich Windl <Ulrich.Windl <at> rz.uni-regensburg.de>, 
 20199 <at> debbugs.gnu.org
Subject: Re: bug#20199: Enhancement request for date's "-d" option: different
 epochs
Date: Wed, 25 Mar 2015 13:10:04 +0000

On 25/03/15 12:26, Ulrich Windl wrote:
> Hi!
> 
> I'm not subscribed to this list, and I hope this is the right place to report an enhancement request as there seems to be no bugzilla for that.
> Anyway: When downloading the current leap seconds list for out NTP server I realized that the dates there seem to be specified in seconds from 1900-01-01_00:00:00 on one hand, and on the other I realized that date's option "-d" only allows UNIX epochs using the "@" notation.
> 
> Therefore I suggest to allow different starting epochs, possible using a syntax like "date -d '1900-01-01+2287785599'" to print the date and time of 2287785599 seconds past January 1st 1900. ("Like" means I suggest the semantics, but are not really proposing a concrete syntax; possibly there are smarter guy around than me)
> 
> Also being able to decode hexadecimal NTP timestamps would be a nice feature: NTp timestamps look like this:
> d8bd24ef.a8e2bb68 meaning "Wed, Mar 25 2015 13:13:35.659...", so it's 32 bit for the seconds and another 32 bit for the fractional seconds (see page 9 of the PostScript or PDF version of RFC 1305: "NTP timestamps are represented as a 64-bit
> unsigned fixed-point number, in seconds relative to 0h on 1 January 1900. The integer part is in the
> first 32 bits and the fraction part in the last 32 bits.")
> 
> Maybe a "tagged" syntax like "-d NTP:d8bd24ef.a8e2bb6" could be used...
> 
> (For consistency other tags like "UNIX:" for the UNIX epoch and "MS-WIN:" for Microsoft Windows could be used. Again smart guys probably know more important epochs than I do)

Note offsets can be negative, so you could set the offset like:

  $ sec=1234567890
  $ date -d @$(($sec + $(date -d 1/1/1900 +%s)))
  Tue Feb 14 23:56:51 GMT 1939

cheers,
Pádraig.

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