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Important notice: This module may eventually be renamed to DateTime::UserTimezone prior to its 1.0 release; if that occurs, it will continue to provide under the current name for at least one year.

A simple Raku module for determining the user's timezone as an Olson (IANA or tz) identifier, particularly useful when formatting dates.

To use:

use Intl::UserTimezone

say user-timezone;  # 'America/New_York'
                    # 'Africa/Malabo'
                    # 'Asia/Tokyo'
                    # 'Etc/GMT'

The returned string does not apply a metazone. If you wish to show a user-facing string like, e.g., "Central European Time", you should use the appropriate functions from Intl::DateTime (NYI, might go into DateTime::*, haven't decided yet ^_^).

For Mac OS and most *nix systems, the region is accurately grabbed from /etc/localtime if it exists. Currently timezones indicated by the $TZ environmental variable are ignored, but will eventually be supported.

For Windows, the ID should be acceptable and better than a GMT offset, but may occasionally be suboptimal. This is because Windows uses its own custom timezone identifiers that do not have a one-to-one relationship with Olsen IDs. The Windows timezone ID is combined with the Windows GeoID to provide a best-guess that should generally be accurate. For example, if your Windows timezone is "Central Standard Time", and your GeoID is 244 (United States), then it will be reported as America/Chicago (others are possible, but there is not enough information to differentiate with America/Indiana/Knox, so the broadest is used). But if your GeoID is 39 (Canada), then it will be reported as America/Winnipeg.


Oftentimes the user may not be aware of their Olsen ID. You may prefer to use the aliased forms such that America/New_York appears as America/Eastern; this information can be found in CLDR's commons/supplemental/metaZones.xml (perhaps in a future version a :meta-zone option?).

What if it doesn't work

If there is a problem determining the timezone, the default will be Etc/GMT, being the most generic, although that's not really an acceptable alternative. If it's clear that UserTimezone cannot determine things for your operating system, or is in some other way not returning the correct results, please file an issue on Github and let's figure out how to make it work on your system.

Version history

  • v0.1.1
    • Removed test code that prevented correct Windows detection.
    • Chomped output to facilitate use in other modules.
  • v0.1
    • Initial release with support for macOS, most *nix machines and beta support Windows


Except as indicated, this module and all its files is provided under the Artistic License 2.0.

Except as indicated

The file windowsZones.xml is Copyright 2020 The Unicode Consortium, and distributed without modification in accordance with its license/terms of use.


A simple module for determinng the user's timezone


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