Path: csiph.com!eternal-september.org!feeder.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: Keith Thompson Newsgroups: alt.comp.hardware.pc-homebuilt,comp.lang.c,comp.lang.ada,comp.programming,alt.os.linux.ubuntu Subject: Re: 'Leap Second' to Be Added on New Year's Eve This Year Date: Sun, 01 Jan 2017 23:46:00 -0800 Organization: None to speak of Lines: 33 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Injection-Info: mx02.eternal-september.org; posting-host="16a71c89bad48345b6871a676d7f8d6a"; logging-data="10929"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX18sysyd0lQRXhwAITJlVvgV" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.1 (gnu/linux) Cancel-Lock: sha1:VcE2QJZIYHxrFqFPyyc96KY/+Zs= sha1:nvupCN/Jd4xMJ5WyKebmapJ7F8k= Xref: csiph.com alt.comp.hardware.pc-homebuilt:35507 comp.lang.c:100851 comp.lang.ada:32634 comp.programming:7228 alt.os.linux.ubuntu:194617 Dänk 42Ø writes: [...] > My question is how this will affect computer programs that convert Unix > Julian time (which keeps time in seconds since 00:00:00 UTC 01 Jan > 1970). That's just Unix time; it's not "Julian". > For example, I have various Perl modules that convert Unix time to > readable timestamps. If my module doesn't include for the leap second, > will my timestamps be one second off? I assume they'll update the > myriad of programming language modules, but how long will this take? > For now, I'll assume the current Perl module has been updated. Typically Unix systems ignore leap seconds. For example, on my system's timestamp as I write this is 1483342650, though allowing for the 37 intervening leap seconds, 1970-01-01 00:00:00 UTC was actually 1483342687 seconds ago. The slightly incorrect representation of old date isn't much of a problem in practice. The system clock was probably adjusted gradually during the period before and after the leap second. > (BTW, I was watching the Berlin clock on timeanddate.com, and their > clock went from 23:59:59 to 00:00:00 -- there was no "23:59:60"). time.gov showed 23:59:60. -- Keith Thompson (The_Other_Keith) kst-u@mib.org Working, but not speaking, for JetHead Development, Inc. "We must do something. This is something. Therefore, we must do this." -- Antony Jay and Jonathan Lynn, "Yes Minister"