What are PO/POT Files? Complete Guide to Gettext Translation Files

PO and POT files are essential components of the GNU gettext localization system, widely used for translating software applications into multiple languages. This guide explains everything you need to know about these file formats and how to use them effectively in your internationalization workflow.

Key File Types

POT files (.pot) - Template files containing original untranslated strings extracted from your source code. They serve as the base for creating language-specific translations.
PO files (.po) - Language-specific files containing both original and translated strings. Created from POT files, they store actual translations for each target language.
MO files (.mo) - Binary compiled versions of PO files optimized for runtime performance. These are what your application actually uses to display translations.

File Structure and Format

PO files follow a specific structure that includes metadata and message entries. Each translation unit consists of:

Translator Comments - Lines starting with # to provide context
Reference Lines - Show where strings appear in source code
msgid - The original untranslated string
msgstr - The translated version of the string

# Example PO file entry
#: src/main.py:42
msgid "Welcome to our application"
msgstr "Bienvenido a nuestra aplicación"

Professional Translation Workflow

Step-by-Step Process

String Extraction: Use xgettext to scan source code and create/update POT files
Template Creation: Generate language-specific PO files from the POT template
Translation: Translate strings using specialized PO editors or translation tools
Validation: Verify translations and resolve fuzzy matches
Compilation: Generate binary MO files using msgfmt
Integration: Deploy MO files and configure locale loading in your application

Best Practices

Version Control: Keep PO files in version control to track translation changes and collaborate effectively
Regular Updates: Maintain POT files in sync with source code to ensure all strings are translatable
Context Comments: Provide clear context for translators using comments and references
Plural Forms: Properly handle plural forms using msgid_plural and appropriate plural rules
Character Encoding: Use UTF-8 encoding consistently across all files
Backup Strategy: Maintain regular backups of translation files

Essential Tools

xgettext: Extracts translatable strings from source code
Poedit: Popular GUI editor for PO files
msgfmt: Compiles PO files into binary MO format
msgmerge: Updates PO files with new strings from POT
msggrep: Searches through PO files

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