From: OZAWA Sakuro <sakuro@2238club.org>
Date: 2010-11-25T12:36:41+09:00
Subject: Re: date of 1 year ago

On Thu, Nov 25, 2010 at 12:14, Stu <stu@rubyprogrammer.net> wrote:

> nice. never knew you could do that with the shell command date.

Remember it is one of GNU date's extension and is not portable.
http://www.opengroup.org/onlinepubs/009695399/utilities/date.html

$ uname -a
Darwin pisces.local 9.8.0 Darwin Kernel Version 9.8.0: Wed Jul 15
16:55:01 PDT 2009; root:xnu-1228.15.4~1/RELEASE_I386 i386 i386 iMac9,1
Darwin

$ /opt/local/bin/gdate -d '1 year ago'
Wed Nov 25 12:35:00 JST 2009

$ /bin/date -d '1 year ago'
usage: date [-jnu] [-d dst] [-r seconds] [-t west] [-v[+|-]val[ymwdHMS]] ...
            [-f fmt date | [[[mm]dd]HH]MM[[cc]yy][.ss]] [+format]

-- 
OZAWA Sakuro

"I think we can agree, the past is over." - George W. Bush