[LEAPSECS] Do good fences make good neighbors?

Poul-Henning Kamp phk at phk.freebsd.dk
Fri Jan 14 19:11:57 EST 2011


In message <p06240800c9568ccc4ca3@[192.168.1.100]>, Joe Gwinn writes:

>At 3:03 PM -0700 1/14/11, Rob Seaman wrote:



>UNIX chose 00:00:00 GMT 1 January 1970 as their epoch simply to be

>synchronized with civil time, at least initially.



The initial versions of the operating system, which later became
UNIX, kept time relative to randomly chosen epochs, which were
updated whenever the counter were in danger of rolling over.

Usually, but not always, the epoch was chosen to be the the beginning
of the current month.

The reason why the "1970-01-01 00:00:00GMT" epoch stuck was they
made the counter 32 bits to "fix the problem once and for all"

(Source: Dennis Ritchie, at breakfast at USENIX ATC 1998 New Orleans)

--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.


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