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tzinfo object for the local timezone

Project description

tzlocal

API CHANGE!

With version 3.0 of tzlocal, tzlocal no longer returned pytz objects, but zoneinfo objects, which has a different API. Since 4.0, it now restored partial compatibility for pytz users through Paul Ganssle’s pytz_deprecation_shim.

tzlocal 4.0 also adds an official function get_localzone_name() to get only the timezone name, instead of a timezone object. On unix, it can raise an error if you don’t have a timezone name configured, where get_localzone() will succeed, so only use that if you need the timezone name.

4.0 also adds way more information on what is going wrong in your configuration when the configuration files are unclear or contradictory.

Info

This Python module returns a tzinfo object (with a pytz_deprecation_shim, for pytz compatibility) with the local timezone information, under Unix and Windows.

It requires Python 3.6 or later, and will use the backports.tzinfo package, for Python 3.6 to 3.8.

This module attempts to fix a glaring hole in the pytz and zoneinfo modules, that there is no way to get the local timezone information, unless you know the zoneinfo name, and under several Linux distros that’s hard or impossible to figure out.

With tzlocal you only need to call get_localzone() and you will get a tzinfo object with the local time zone info. On some Unices you will still not get to know what the timezone name is, but you don’t need that when you have the tzinfo file. However, if the timezone name is readily available it will be used.

Supported systems

These are the systems that are in theory supported:

  • Windows 2000 and later
  • Any unix-like system with a /etc/localtime or /usr/local/etc/localtime

If you have one of the above systems and it does not work, it’s a bug. Please report it.

Please note that if you are getting a time zone called local, this is not a bug, it’s actually the main feature of tzlocal, that even if your system does NOT have a configuration file with the zoneinfo name of your time zone, it will still work.

You can also use tzlocal to get the name of your local timezone, but only if your system is configured to make that possible. tzlocal looks for the timezone name in /etc/timezone, /var/db/zoneinfo, /etc/sysconfig/clock and /etc/conf.d/clock. If your /etc/localtime is a symlink it can also extract the name from that symlink.

If you need the name of your local time zone, then please make sure your system is properly configured to allow that.

If your unix system doesn’t have a timezone configured, tzlocal will default to UTC.

Usage

Load the local timezone:

>>> from tzlocal import get_localzone
>>> tz = get_localzone()
>>> tz
<DstTzInfo 'Europe/Warsaw' WMT+1:24:00 STD>

Create a local datetime:

>>> from datetime import datetime
>>> dt = datetime(2015, 4, 10, 7, 22, tzinfo=tz)
>>> dt
datetime.datetime(2015, 4, 10, 7, 22, tzinfo=<DstTzInfo 'Europe/Warsaw' CEST+2:00:00 DST>)

Lookup another timezone with zoneinfo (backports.zoneinfo on Python 3.8 or earlier):

>>> from zoneinfo import ZoneInfo
>>> eastern = ZoneInfo('US/Eastern')

Convert the datetime:

>>> dt.astimezone(eastern)
datetime.datetime(2015, 4, 10, 1, 22, tzinfo=<DstTzInfo 'US/Eastern' EDT-1 day, 20:00:00 DST>)

If you just want the name of the local timezone, use get_localzone_name():

>>> from tzlocal import get_localzone_name
>>> get_localzone_name()
"Europe/Warsaw"

Please note that under Unix, get_localzone_name() may fail if there is no zone configured, where get_localzone() would generally succeed.

Development

To create a development environment, create a virtualenv and make a development installation:

$ virtualenv ve
$ source ve/bin/activation (Win32: .\ve\Scripts\activate)
(ve) $ pip install -e .[test,devenv]

To run tests, just use pytest, coverage is nice as well:

(ve) $ pytest --cov=tzlocal

Maintainer

Contributors

  • Marc Van Olmen
  • Benjamen Meyer
  • Manuel Ebert
  • Xiaokun Zhu
  • Cameris
  • Edward Betts
  • McK KIM
  • Cris Ewing
  • Ayala Shachar
  • Lev Maximov
  • Jakub Wilk
  • John Quarles
  • Preston Landers
  • Victor Torres
  • Jean Jordaan
  • Zackary Welch
  • Mickaël Schoentgen
  • Gabriel Corona
  • Alex Grönholm
  • Julin S
  • Miroslav Šedivý
  • revansSZ
  • Sam Treweek

(Sorry if I forgot someone)

Changes

4.1 (2021-10-29)

  • No changes from 4.1b1.

4.1b1 (2021-10-28)

  • It turns out a lot of Linux distributions make the links between zoneinfo aliases backwards, so instead of linking GB to Europe/London it actually links the other way. When /etc/localtime then links to Europe/London, and you also have a config file saying Europe/London, the code that checks if /etc/localtime is a symlink ends up at GB instead of Europe/London and we get an error, as it thinks GB and Europe/London are different zones.

    So now we check the symlink of all timezones in the uniqueness test. We still return the name in the config file, though, so you would only get GB or Zulu returned as the time zone instead of Europe/London or UTC if your only configuration is the /etc/localtime symlink, as that’s checked last, and tzlocal will return the first configuration found.

  • The above change also means that GMT and UTC are no longer seen as synonyms, as zoneinfo does not see them as synonyms. This might be controversial, but you just have to live with it. Pick one and stay with it. ;-)

4.0.2 (2021-10-26)

  • Improved the error message when you had a conflict including a /etc/localtime symlink.

4.0.1 (2021-10-19)

  • A long time bug in Ubuntu docker images seem to not get fixed, so I added a workaround.

4.0.1b1 (2021-10-18)

  • Handle UCT and Zulu as synonyms for UTC, while treating GMT and UTC as different.

4.0 (2021-10-18)

  • No changes.

4.0b5 (2021-10-18)

  • Fixed a bug in the Windows DST support.

4.0b4 (2021-10-18)

  • Added support for turning off DST in Windows. That only works in whole hour timezones, and honestly, if you need to turn off DST, you should just use UTC as a timezone.

4.0b3 (2021-10-08)

  • Returning pytz_deprecation_shim zones to lower the surprise for pytz users.
  • The Windows OS environment variable ‘TZ’ will allow an override for setting the timezone. The override timezone will be asserted for timezone validity bit not compared against the systems timezone offset. This allows for overriding the timezone when running tests.
  • Dropped support for Windows 2000, XP and Vista, supports Windows 7, 8 and 10.

4.0b2 (2021-09-26)

  • Big refactor; Implemented get_localzone_name() functions.
  • Adding a Windows OS environment variable ‘TZ’ will allow an override for setting the timezone (also see 4.0b3).

4.0b1 (2021-08-21)

  • Now finds and compares all the configs (under Unix-like systems) and tells you what files it found and how they conflict. This should make it a lot easier to figure out what goes wrong.

3.0 (2021-08-13)

  • Modernized the packaging, moving to setup.cfg etc.
  • Handles if the text config files incorrectly is a TZ file. (revanSZ)

3.0b1 (2020-09-21)

  • Dropped Python 2 support
  • Switched timezone provider from pytz to zoneinfo (PEP 615)

2.1 (2020-05-08)

  • No changes.

2.1b1 (2020-02-08)

  • The is_dst flag is wrong for Europe/Dublin on some Unix releases. I changed to another way of determining if DST is in effect or not.
  • Added support for Python 3.7 and 3.8. Dropped 3.5 although it still works.

2.0.0 (2019-07-23)

  • No differences since 2.0.0b3

Major differences since 1.5.1

  • When no time zone configuration can be find, tzlocal now return UTC. This is a major difference from 1.x, where an exception would be raised. This change is because Docker images often have no configuration at all, and the unix utilities will then default to UTC, so we follow that.
  • If tzlocal on Unix finds a timezone name in a /etc config file, then tzlocal now verifies that the timezone it fouds has the same offset as the local computer is configured with. If it doesn’t, something is configured incorrectly. (Victor Torres, regebro)
  • Get timezone via Termux getprop wrapper on Android. It’s not officially supported because we can’t test it, but at least we make an effort. (Jean Jordaan)

Minor differences and bug fixes

  • Skip comment lines when parsing /etc/timezone. (Edward Betts)
  • Don’t load timezone from current directory. (Gabriel Corona)
  • Now verifies that the config files actually contain something before reading them. (Zackary Welch, regebro)
  • Got rid of a BytesWarning (Mickaël Schoentgen)
  • Now handles if config file paths exists, but are directories.
  • Moved tests out from distributions
  • Support wheels

1.5.1 (2017-12-01)

  • 1.5 had a bug that slipped through testing, fixed that, increased test coverage.

1.5 (2017-11-30)

  • No longer treats macOS as special, but as a unix.
  • get_windows_info.py is renamed to update_windows_mappings.py
  • Windows mappings now also contain mappings from deprecated zoneinfo names. (Preston-Landers, regebro)

1.4 (2017-04-18)

  • I use MIT on my other projects, so relicensing.

1.4b1 (2017-04-14)

  • Dropping support for Python versions nobody uses (2.5, 3.1, 3.2), adding 3.6 Python 3.1 and 3.2 still works, 2.5 has been broken for some time.
  • Ayalash’s OS X fix didn’t work on Python 2.7, fixed that.

1.3.2 (2017-04-12)

  • Ensure closing of subprocess on OS X (ayalash)
  • Removed unused imports (jwilk)
  • Closes stdout and stderr to get rid of ResourceWarnings (johnwquarles)
  • Updated Windows timezones (axil)

1.3 (2016-10-15)

  • #34: Added support for /var/db/zoneinfo

1.2.2 (2016-03-02)

  • #30: Fixed a bug on OS X.

1.2.1 (2016-02-28)

  • Tests failed if TZ was set in the environment. (EdwardBetts)
  • Replaces os.popen() with subprocess.Popen() for OS X to handle when systemsetup doesn’t exist. (mckabi, cewing)

1.2 (2015-06-14)

  • Systemd stores no time zone name, forcing us to look at the name of the file that localtime symlinks to. (cameris)

1.1.2 (2014-10-18)

  • Timezones that has 3 items did not work on Mac OS X. (Marc Van Olmen)
  • Now doesn’t fail if the TZ environment variable isn’t an Olsen time zone.
  • Some timezones on Windows can apparently be empty (perhaps the are deleted). Now these are ignored. (Xiaokun Zhu)

1.1.1 (2014-01-29)

  • I forgot to add Etc/UTC as an alias for Etc/GMT.

1.1 (2014-01-28)

  • Adding better support for OS X.
  • Added support to map from tzdata/Olsen names to Windows names. (Thanks to Benjamen Meyer).

1.0 (2013-05-29)

  • Fixed some more cases where spaces needs replacing with underscores.
  • Better handling of misconfigured /etc/timezone.
  • Better error message on Windows if we can’t find a timezone at all.

0.3 (2012-09-13)

  • Windows 7 support.
  • Python 2.5 supported; because it only needed a __future__ import.
  • Python 3.3 tested, it worked.
  • Got rid of relative imports, because I don’t actually like them, so I don’t know why I used them in the first place.
  • For each Windows zone, use the default zoneinfo zone, not the last one.

0.2 (2012-09-12)

  • Python 3 support.

0.1 (2012-09-11)

  • Initial release.

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