Internationalization and Localization

• https://en.wikipedia.org/wiki/Internationalization_and_localization
• g11n (Globalization)
  • The complete process of making a product ready for the entire world.
• i18n (Internationalization)
  • Engineering the code framework to handle data dynamically using placeholders instead of hardcoded values
• t9n (Translation)
  • Translation is strictly about changing text between languages
  • It is part of localization
  • English: Your total is one hundred dollars
  • French: Votre total est de cent dollars
• l10n (Localization)
  • Localization incorporates translation but also injects functional regional logic
  • French: Votre total est de 92,00 € (changes currency accordingly)
• g11n = i18n + l10n

Clock

Real-Time Clock (RTC)

• aka Hardware Clock
• Physical battery powered clock chip on motherboard
• when computer boots up, OS reads this once and ignores it till shutdown
• https://en.wikipedia.org/wiki/Real-time_clock

sudo hwclock --show

System Clock

• aka Software Clock
• Once OS boots up and reads the RTC, the kernel takes over and counts time dynamically by tracking CPU interrupts or clock ticks
• constantly synced using NTP (Network Time Protocol)
• Linux stores system time using epoch
  • epoch represents number of non-leap seconds which have passed since 00:00:00 UTC on Thursday, 1 January 1970
  • Its precision can be seconds, milliseconds, nanoseconds
  • https://en.wikipedia.org/wiki/Unix_time

# epoch seconds
> date +%s         
1786188795
 
# epoch milliseconds
> date +%s%3N
1786188872644
 
# epoch nanoseconds
> date +%s%N
1786188884030439201

• System clock uses following hardware under the hood
  • Timestamp counter (TSC)
    • It is CPU register
    • The TSC counts every single electrical cycle the CPU core executes
  • High Precision Event Timer (HPET)
    • It is a chip on motherboard
    • Ticks at an un-shifting, constant frequency
    • If the Linux kernel detects that your CPU cores are changing speeds dynamically due to heat or power-saving adjustments, The kernel will start using HPET
• Clock drifting
  • If the clocks drift from network time, NTP resolves it using two methods:
    • Stepping
      • Instantly alters the system clock to match the correct time exactly
      • It breaks the monotonicity of time
      • It can cause crashes of databases, application logs etc.
      • Happens if time error > 128 ms
    • Slewing
      • Gradually adjusts the system clock rate until it matches the correct time without making any instant leaps
      • Time flows smoothly and never moves backward

# use date command for quick modifications
date
 
# modern command to manage global date time
# show date, time, timezone, NTP service status, RTC time
timedatectl

Timezone

• Timezone related files
  • /usr/share/zoneinfo/
    • Pre-compiled binary rule files for every geographic region on Earth
  • /etc/localtime
    • System default timezone
    • Symlink to one of the timezone in /usr/share/zoneinfo/
    • Example symlink to /usr/share/zoneinfo/Asia/Kolkata
• How timezone is evaluated
  • TZ variable (if set) —> /etc/localtime (if symlink present) —> UTC

# list timezones
timedatectl list-timezones
 
# see current timezone
date +"%Z %z"
timedatectl

Locale

• locale command lists different settings for locale
  • LANG is default global blueprint
  • LC_* are specific categories
  • LC_ALL forcibly overwrites all categories
  • LANGUAGE defines a colon-separated list of fallback languages
• To evaluate config for a category
  • LC_ALL (if set) —> LC_* (if set) —> LANG
• For text translations (language, not locale)
  • LANGUAGE (if set, try for all fallbacks) —> LC_ALL —> LC_* —> LANG
• Locale related files
  • /usr/share/i18n/locales/ (Source text files)
    • Human readable data
  • /usr/lib/locale/locale-archive (Binary database)
    • Single optimized binary used by programs

# current locale settings
> locale
LANG=en_IN
LANGUAGE=en_IN:en
LC_CTYPE="en_IN"
LC_NUMERIC="en_IN"
LC_TIME="en_IN"
LC_COLLATE="en_IN"
LC_MONETARY="en_IN"
LC_MESSAGES="en_IN"
LC_PAPER="en_IN"
LC_NAME="en_IN"
LC_ADDRESS="en_IN"
LC_TELEPHONE="en_IN"
LC_MEASUREMENT="en_IN"
LC_IDENTIFICATION="en_IN"
LC_ALL=
 
# list available locales
> locale -a
C
C.utf8
en_IN
en_IN.utf8
POSIX
 
# list available char maps (character sets)
> locale -m
 
# See raw formatting strings queried from locale database
> locale LC_TELEPHONE
+%c ;%a ;%l
 
00
91
UTF-8

• Documentation on locale

# flags
man locale
# internal file syntax
man 5 locale
# specs and precedence rules
man 7 locale

• Syntax
  • Language: ISO 639
    • Uses 2-letter codes (ISO 639-1 or ISO 639 Alpha-2)
    • Maintained by Library of Congress (LOC)
    • examples: en, hi, fr
    • https://www.loc.gov/standards/iso639-2/php/code_list.php
  • Country code: ISO 3166
    • Uses 2-letter codes (ISO 3166-1 or ISO 3166 Alpha-2)
    • Maintained by International Organization for Standardization (ISO)
    • If omitted, master config will be used for example en (English)
    • examples: US, IN, DE
    • https://www.iso.org/obp/ui/#search
  • Character set: IANA Charset Registry
    • Maintained by Assigned Numbers Authority (IANA)
    • If omitted, system will guess based on language/region
      • for en_US, it will be ISO-8859-1 (Latin-1)
    • examples: UTF-8, ISO-8859-1 (Latin-1), ANSI_X3.4-1968 (ASCII)
    • https://www.iana.org/assignments/character-sets

language[_country-code][.character-set]

• POSIX or C
  • They are special locales
  • They are aliases of each other
  • no language code or country code used
  • It completely bypasses locale system and uses source code text which is generally in english language
  • Character Set: ANSI_X3.4-1968 (ASCII)

Locale Categories

• LC_COLLATE: Controls alphabetical sorting logic
  • A, B, a, b (Dictionary order)
  • A, B, C, ..., a, b, c (ASCII order)
• LC_CTYPE: Character type and encoding
  • UTF-8 is encoding
  • Mapping between lowercase and uppercase
    • English (en_US): i —> I
    • Turkish (tr_TR): i —> İ
• LC_TIME: Set date and time display
  • 03/07/2026 (India) vs 07/03/2026 (USA)
  • 14:30 (24 hour) vs 02:30 (12 hour)
• LC_NUMERIC: Sets number punctuation
  • 1,234.56 (USA)
  • 1.234,56 (German)
• LC_MONETARY
  • ₹100 (India)
  • 100 € (UK)
• LC_MESSAGES: Sets language used for OS errors and warnings
  • Permission denied (English)
  • Permission refusée (French)
• LC_PAPER: Sets physical paper dimensions
  • Letter (US)
  • A4 (India)
• LC_NAME: Formats name and titles
  • Mr. John Smith (US)
  • Smith John (Hungary)
• LC_ADDRESS: Formats mailing address
  • USA: City, State, ZIP code (New York, NY 10001)
  • Germany: ZIP code before City (10117 Berlin)
• LC_TELEPHONE: Formats telephone numbers
  • (555) 123-4567 (USA)
  • +91 XXXXX-XXXXX (India)
• LC_MEASUREMENT: Sets unit of measurement
  • USA: Miles, Pounds, Fahrenheit
  • India: Kilometers, Kilograms, Celsius