[Discuss] Interesting linux date bug

[pw]

DR wrote:
> pw wrote:
>> DR wrote:
>>> pw wrote:
>>>> Alan W. Irwin wrote:
>>>>> On 2008-03-03 11:34-0800 pw wrote:
>>>>>
>>>>>> Apparently this second didn't exist:
>>>>>>
>>>>>> date -u -d "12/31/1969 23:59:59" +%s
>>>>>
>>>>> What distro are you using? That command works fine on my (64-bit) 
>>>>> Debian
>>>>> testing system:
>>>>>
>>>>> irwin at raven> date -u -d "12/31/1969 23:59:59" +%s
>>>>> -1
>>>>>
>>>>> Also, the epoch for one second later also works....
>>>>>
>>>>> irwin at raven> date -u -d "01/01/1970 00:00:00" +%s
>>>>> 0
>>>>>
>>>>> Just to throw a curve ball into the discussion, watch out for leap 
>>>>> seconds,
>>>>> see http://en.wikipedia.org/wiki/Unix_time.  The above epochs did 
>>>>> not have
>>>>> leap seconds, but apparently there are Unix computer-time 
>>>>> inconsistencies at
>>>>> epochs where leap seconds (necessary to account for the varying 
>>>>> rotation
>>>>> rate of the earth) occur.
>>>>>
>>>>> Alan
>>>>
>>>> I'm using centos on that machine. Centos is a peared down
>>>> redhat style distro.
>>>>
>>>> The seconds on either side of that work fine. The actual +%s
>>>> value of that second should be -1 (negative one), just as you show.
>>>> On that machine the date comes up as invalid.
>>>>
>>>> This is not really a big deal for me. I only noticed this because
>>>> I was making a table of unix seconds values for the ends of years.
>>>>
>>>> ie:
>>>>
>>>> for YEAR in `seq 1900 2035`; do date -u -d "01/01/$YEAR 23:59:59" 
>>>> +%s; done
>>>>
>>>> Does the linux date have a leap seconds flag/setting.
>>>> Maybe that's the problem.
>>>>
>>>> Peter
>>>
>>> I am using:
>>>
>>> Centos Version 5
>>> date (GNU coreutils) 5.97
>>>
>>> and I get the following results:
>>>
>>> $ date -u -d "12/31/1969 23:59:58" +%s
>>> -2
>>> $ date -u -d "12/31/1969 23:59:59" +%s
>>> -1
>>> $ date -u -d "01/01/1970 00:00:00" +%s
>>> 0
>>> $ date -u -d "01/01/1970 00:00:01" +%s
>>> 1
>>>
>>> Deid
>>
>> My version of Centos.
>>
>> Linux version 2.6.9-42.ELsmp (buildcentos at build-i386) (gcc version 
>> 3.4.6 20060404 (Red Hat 3.4.6-3)) #1 SMP Sat Aug 12 09:39:11 CDT 2006
>>
>> Running on dual Xeons and a gig of memory.
> 
> Linux giga 2.6.18-53.1.4.el5xen #1 SMP Fri Nov 30 01:53:35 EST 2007 i686 
> athlon i386 GNU/Linux
> 
> AMD Athlon(tm) 64 X2 Dual Core Processor 3800+
> 
> 1 gig of memory.
> 
> ]$ for YEAR in `seq 1968 1970`; do date -u -d "12/31/$YEAR 23:59:59" 
> +%s; done
> 
> Gives:
> 
> -31536001
> -1
> 31535999
> 
> Mmmmm?
> 
> Deid

Hmmmm...
You have 4 aces and I only have a full house....

;)

Peter