The LC_TIME option for forcing a Locale (format and language) for Dates and Time

International
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Perplexity prompt:

As an expert in the Gramps software source code, Python, and systems for configuring software internationalization, please provide a detailed explanation of the LC_TIME option. Include its origin in the POSIX standard, the meaning of the LC acronym, and a brief list of other LC options. Describe how LC_TIME affects date and time formatting, giving examples specific to Gramps software, including usage in French, Hebrew, and a non-UTF-8 locale with an abbreviated month name. Explain whether the LC_TIME setting is persistent, and if not, how to make it persistent or use it for a single session. Include considerations for Gramps development regarding LC_TIME implementation.

LC_TIME is a locale category option defined in the POSIX (Portable Operating System Interface) standard, which governs the formatting of dates and times in software applications. The “LC” in LC_TIME stands for “Locale Category,” and it’s part of a broader set of locale-related environment variables used for internationalization.

Origin and Related LC Options

The POSIX standard introduced LC_ variables to provide fine-grained control over various aspects of localization. Some key LC options include:

  1. LC_TIME : Date and time formatting
  2. LC_NUMERIC : Number formatting
  3. LC_MONETARY : Currency formatting
  4. LC_MESSAGES : Language for system messages
  5. LC_CTYPE : Character classification and case conversion
  6. LC_COLLATE : String collation order

LC_TIME in Gramps

In Gramps, a genealogy software where date handling is crucial, LC_TIME plays a significant role in determining how dates are displayed and interpreted. It affects:

  • Names of days and months
  • Date formats (short and long)
  • Time formats (12-hour vs. 24-hour)
  • AM/PM indicators

Examples in Different Locales

  1. English (US):

    $ export LC_TIME=en_US.UTF-8
$ gramps --config=database.backend:sqlite -O "FamilyTree" -a tool -p name=datestest
10/12/2024

  2. French:

    $ export LC_TIME=fr_FR.UTF-8
$ gramps --config=database.backend:sqlite -O "ArbreFamilial" -a tool -p name=datestest
12/10/2024

  3. Hebrew:

    $ export LC_TIME=he_IL.UTF-8
$ gramps --config=database.backend:sqlite -O "עץ משפחה" -a tool -p name=datestest
12.10.2024

  4. German (non-UTF-8 with abbreviated month):

    $ export LC_TIME=de_DE@euro
$ gramps --config=database.backend:sqlite -O "Stammbaum" -a tool -p name=datestest
12. Okt 2024

    This example uses the de_DE@euro locale, which typically uses ISO-8859-15 encoding instead of UTF-8, and displays the abbreviated month name.

Persistence of LC_TIME

By default, LC_TIME settings made using the export command are not persistent across sessions. To make them persistent:

  1. For user-specific settings, add to ~/.bashrc:

    echo 'export LC_TIME=fr_FR.UTF-8' >> ~/.bashrc

  2. For system-wide settings, edit /etc/locale.conf:

    sudo echo 'LC_TIME=fr_FR.UTF-8' >> /etc/locale.conf

For a single session or command:

LC_TIME=he_IL.UTF-8 gramps

Considerations for Gramps Development

  1. Locale Awareness: Ensure Gramps respects LC_TIME while allowing user overrides.
  2. Date Parsing: Implement robust parsing for various input formats based on LC_TIME.
  3. Report Generation: Consider LC_TIME settings when generating reports.
  4. Calendar Systems: Support different calendar systems alongside LC_TIME settings.
  5. User Interface: Provide options to override system LC_TIME settings within Gramps.
  6. Testing: Ensure correct behavior across various LC_TIME settings, including non-UTF-8 locales.
  7. Default Fallback: Implement sensible defaults when LC_TIME is not set or unsupported.
  8. Encoding Handling: Properly handle different encodings, especially when dealing with non-UTF-8 locales.
  9. Abbreviated Names: Support abbreviated month and day names in various languages and formats.

By properly implementing LC_TIME support, Gramps can provide a localized experience while maintaining the flexibility needed for genealogical research across different cultures and time periods. Developers should be aware of the interaction between LC_TIME and other locale settings, ensuring that date and time representations are consistent and culturally appropriate throughout the application.

When working with non-UTF-8 locales, extra care should be taken to ensure proper character encoding and display, especially when dealing with languages that use non-Latin scripts or special characters. This is particularly important in genealogy software like Gramps, where accurate representation of names and dates from various cultures and time periods is crucial.

Citations:

  1. POSIX.1-2024 (IEEE Std 1003.1-2024) : Locale
  2. Gramps wiki : Environmental Variables
    (LANG, LANGUAGE, LC_MESSAGE, LC_TIME)
  3. Gramps wiki : How to: Change the language of reports
  4. how to edit LC_TIME variables: date_fmt, d_t_fmt, t_fmt? - Install/Boot/Login - openSUSE Forums
  5. Locale - ArchWiki
  6. https://www.ibm.com/docs/nl/aix/7.2?topic=ff-lc-time-category-locale-definition-source-file-format
  7. date
  8. https://www.baeldung.com/linux/locale-environment-variables
  9. python - What is the difference between C.UTF-8 and en_US.UTF-8 locales? - Stack Overflow
  10. c - Which components use the locale variables? - Stack Overflow
  11. bash - Forcing "date" to use a locale other than the machine default - Stack Overflow

Troubleshooting LC_TIME

If your Gramps is experiencing will not parse dates in a Language even after setting LC_TIME to that language, there are a few possibilities to consider:

Possible Causes

  1. Incorrect Locale Configuration:

    • The LC_TIME setting may not be properly applied or overridden by other locale settings.
    • LANG or LC_ALL might be taking precedence over LC_TIME.

  2. Gramps-specific Settings:

    • Gramps has its own date format settings that might be overriding system locale settings.

  3. Input Method:

    • The input method for German might be affecting date recognition, regardless of locale settings.

Troubleshooting Steps

  1. Verify System Locale:

    • Check all locale settings, not just LC_TIME:
      locale
    • Ensure LC_TIME is set correctly:
      echo $LC_TIME

  2. Check Gramps Settings:

    • In Gramps, go to Edit > Preferences > Display
    • Verify the “Date format” setting
    • Ensure “Calendar on input” is set to the desired option

  3. Restart Gramps:

    • Some Gramps settings require a restart to take effect

  4. Test Date Input:

    • Try entering dates in both German and English formats to see which are recognized

  5. Check Input Method:

    • Ensure the correct input method is selected when entering dates

  6. Gramps Version:

    • Verify the user is running the latest version of Gramps, as older versions might have bugs related to date parsing

  7. Temporary Locale Change:

    • Try running Gramps with a temporary locale change:
      LC_TIME=en_US.UTF-8 gramps
  1. Database Check:
    • Run the Database Repair tool in Gramps to ensure there are no data inconsistencies

If these steps don’t resolve the issue, the user might need to:

  • Report the issue to the Gramps development team
  • Check if there’s a conflict between the German QWERTZ keyboard layout and the desired date input format
  • Consider using the Date selection dialog in Gramps for precise date entry, bypassing potential keyboard/locale conflicts

Remember, the physical keyboard layout (QWERTZ) should not directly affect date parsing. The issue is more likely related to locale settings or Gramps-specific configurations.

Citations:

  1. Format dates from day-month-year
  2. Entering and Editing Data: Complete Description
  3. Gramps 5.2 Wiki Manual - Settings - Gramps
  4. Gramps 5.2 Wiki Manual - Settings - Gramps
  5. System Locale and Keyboard Configuration :: Fedora Docs
  6. Gramps 5.2 Wiki Manual - Entering and editing data: detailed - part 1 - Gramps
  7. Automatic USB keyboard language detection · GitHub
  8. Automatically switch keyboard to match language of surrounding text - English - Ask LibreOffice

The specific issue of LANG or LC_ALL taking precedence over LC_TIME does not turn up specific articles. However, based on the information provided and the AI training, here are some insights on troubleshooting this issue:

Locale Precedence

  1. LC_ALL Override:

    • If set, LC_ALL takes precedence over all other locale settings, including LC_TIME and LANG[1][2].
    • Check if LC_ALL is set: echo $LC_ALL

  2. LANG as Fallback:

    • If LC_TIME is not set, the system will use LANG as a fallback[5].
    • Verify LANG setting: echo $LANG

Troubleshooting Steps

  1. Check Current Settings:

    locale

    This will show all current locale settings[1][3].

  2. Verify LC_TIME:

    echo $LC_TIME

    Ensure it’s set to the desired value (e.g., en_US.UTF-8 for English).

  3. Temporary Test:
    Try running Gramps with a specific LC_TIME setting:

    LC_TIME=en_US.UTF-8 gramps

    This overrides other settings temporarily[4].

  4. Check Configuration Files:

    • On most Linux systems, check /etc/locale.conf[5].
    • On some systems, check /etc/default/locale.

  5. Application-Specific Settings:

    • Gramps might have its own locale handling. Check its configuration files or settings menu.

  6. System-Wide vs. User Settings:

    • User-specific settings in ~/.bashrc or ~/.profile might override system settings.

  7. Conflicting Configurations:

    • Look for conflicting settings in different configuration files[1].

  8. Locale Generation:

    • Ensure the required locales are generated:
      locale -a
    • If missing, generate them:
      sudo locale-gen en_US.UTF-8

  9. Desktop Environment Influence:

    • Some desktop environments (like KDE) can override system locale settings[2].

Citations:

  1. [all variants] LC_ALL locale issue
  2. locale: Cannot set LC_ALL to default locale: No such file or [SOLVED] / Newbie Corner / Arch Linux Forums
  3. https://forums.raspberrypi.com/viewtopic.php?t=202169
  4. Checking the locale configuration on UNIX platforms
  5. System Locale and Keyboard Configuration :: Fedora Docs
  6. Format dates from day-month-year
  7. ubuntu - Linode Lish bash: warning: setlocale: LC_ALL: cannot change locale (en_US.UTF-8) - Stack Overflow
  8. Keyboard - Debian Wiki
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