From: Tanaka Akira <akr@...>
Date: 2011-01-05T13:39:21+09:00
Subject: Re: Time + time.local

2011-01-04 15:45 d c <lister@pikkle.com>:
>
> I cant seem to get localtime to work, can anyone share some gotchas?

Ruby uses a C-level function, localtime(), to obtain the timezone
information .
localtime() uses the timezone OS provides.

POSIX defines a form of TZ environment variable.
http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html

According to this definition, JST-9 represent the timezone of Japan.

% TZ=JST-9 ./ruby -ve 't = Time.now; p [t, t.zone]'
ruby 1.9.3dev (2011-01-01 trunk 30441) [i686-linux]
[2011-01-05 13:25:36 +0900, "JST"]

If OS uses tzcode by Arthur David Olson,
TZ format is extended for the location's full name.
http://www.twinsun.com/tz/tz-link.htm

> irb(main):009:0> t1.localtime("+09:00")
> ArgumentError: wrong number of arguments (1 for 0)
>        from (irb):9:in `localtime'
>        from (irb):9
>        from :0
>
> ## according to docs this should work:
> http://www.ruby-doc.org/core/classes/Time.html#M000346

time.localtime(utc_offset) is available since Ruby 1.9.2.
-- 
Tanaka Akira