September 24, 2022

Show the time of other time zones from the command line

To show the time of a time zone in your shell (terminal) run:

$ TZ=<tzdata> date

For example:

$ TZ=America/New_York date

or

$ TZ=Asia/Istanbul date

Use history to look up a time again

If you need to look up a time again, you can use CRTL + R to retrieve a command from your shell history.

For example: type CRTL + R and then start typing ‘Istanbul’ for instance i, s, t etc; then enter.

Set an alias (shortcut)

You can also assign an alias.

To assign an alias (shortcut) for $ TZ=America/New_York date you can run:

$ alias nytime='TZ=America/New_York date'

now if you run $ nytime the shell should output the date and time in New York.

To undo the alias nytime run:

$ unalias nytime

To list all alias run:

$ alias

Show the local time for a given day and time in another time zone

For example, to show the local time for 9 AM next Friday on the west coast of the US run:

          $ date --date='TZ="America/Los_Angeles" 09:00 next Fri'

should show the equivalent time in your (local) time zone¹.

Find the ‘tzdata’ of the time you want to look up

You can find a list of all tzdata by running:

$ tzselect

You should see:

Please identify a location so that time zone rules can be set correctly.
Please select a continent, ocean, "coord", or "TZ".
1) Africa                                7) Europe
2) Americas                              8) Indian Ocean
3) Antarctica                                9) Pacific Ocean
4) Asia                                 10) coord - I want to use geographical coordinates.
5) Atlantic Ocean                           11) TZ - I want to specify the timezone using the Posix TZ format.
6) Australia
#?

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1. Example drawn from date’s manual which you can see by running $man date in the shell↩︎

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