On Sat, Apr 03, 2021 at 05:26:43PM +0800, Shironeko wrote: > tz database and tools using it like the date(1) command can convert between > local times taking into account all the difference like daylight savings time. > An example below, Toronto observes daylight savings whereas Shanghai does not: [...] > The ambiguity caused by dialing back is resolved with > $ TZ=Asia/Shanghai date --date='TZ="America/Toronto" 2021-11-07 Sun 01:30 EDT' > Sun 7 Nov 13:30:00 CST 2021 > $ TZ=Asia/Shanghai date --date='TZ="America/Toronto" 2021-11-07 Sun 01:30 EST' > Sun 7 Nov 14:30:00 CST 2021 I understand that. Yo've got to specify (EDT vs EST) whether summer time was in effect when taking the time stamp. But then, why not specify the offset right away? Less dependency on "ambient" information. No dependency at all on whether the database has changed [1] under you. And so on. Of course, the ideal would be to keep time in UTC and display accordingly to the time zone (ideally also, provided with each time stamp). But I fear this would be pushing things too far... Cheers [1] This Shouldn't Happen (famous last words ;-) - t