On Wed, Apr 8, 2015 at 7:32 PM, Chris Angelico <rosuav@gmail.com> wrote:
On Thu, Apr 9, 2015 at 8:32 AM, Alexander Belopolsky <alexander.belopolsky@gmail.com> wrote:
A "named offset" is an abbreviation such as UTC, EST, MSK, MSD which (at any given time) corresponds to a fixed offset from UTC.
That assumes the abbreviations are unique. They're not. Just this morning I had to explain to a new student of mine that no, my time zone is not "EST" = New York time, it's actually "EST" = Melbourne time. Granted, most of the time New York and Melbourne are opposite on DST, so one will be EST and one EDT, but that trick won't always help you.
I should have been more precise in my definitions. A "named offset" is a pair (tm_gmtoff, tm_zone). Given a location and a UTC time (UNIX timestamp), you should be able to produce a "named offset". $ TZ=Australia/Melbourne date -d @1428536256 +"%z %Z" +1000 EST The "name" part is usually redundant, but convenient for human readers. The opposite is not true: you cannot derive location from either or both parts.