[Discuss] Interesting linux date bug

[pw]

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

That's what it should look like.

There is actually an error in my email.
The script should read:

for YEAR in `seq 1900 2035`; do date -u -d "12/31/$YEAR 23:59:59" +%s; done

since I am looking at 'Dec 31' of each year.
No coffee is my excuse.

Peter