Working remotely for a timezone-distributed company poses an interesting challenge: that of having to figure out dates and times for people in different timezones. This involves not only the relatively trivial “what time is it now in A_FARAWAY_PLACE”, but “what time, in FARAWAY_PLACE_X, will it be in FARAWAY_PLACE_Z” and other fun things.
I’ve known how to use the “date” command to show the date on a different place/timezone, which is already a huge timesaver:
$ TZ="Taiwan/Taipei" date
Fri Apr 12 19:25:31 Taiwan 2019
but – today I was trying to answer “what time in TZ=”America/Chicago” is 1 PM, on Tuesday, in “UK/London“. This is interesting because it’s conversion between two timezones which are not the one I’m in, of a date/time in the future. So I was checking date’s man page for “how to convert a specific point in time”, when I realized date can do this for you! Right in the man page there’s this example:
Show the local time for 9AM next Friday on the west coast of the US
$ date --date='TZ="America/Los_Angeles" 09:00 next Fri'
so then I combined that with the earlier one to come up with:
$ TZ="America/Chicago" date --date='TZ="UK/London" 1:00 PM next Tue'
Tue Apr 16 08:00:00 CDT 2019
- TZ argument to calculate dates for a specific timezone, not the current one
- –date parameter to “display time described by STRING, not ‘now'”
- Descriptive time specifications (1:00 PM next Tuesday – this is a pseudo-human-readable format which is not entirely intuitive – info date has the specifics)
- TZ support *inside* the descriptive specification
And a list of known timezones can be obtained with