getText

gettext is a framework for software internationalization and localization, originally developed as part of the GNU project. It provides a standard runtime library and workflow that allow applications to display messages in a user’s language without embedding translations in source code. The approach separates translatable strings from program logic and stores translations in message catalogs.

Translatable strings are collected into template files called pot files, and translated versions are stored in po files. Each entry has the original string (msgid) and its translation (msgstr). At runtime, the program looks up translations in compiled binary catalogs (mo files) loaded from a locale directory structure organized by locale and domain. A domain usually corresponds to a program or module, and the locale directory follows the pattern locale/<locale>/LC_MESSAGES/<domain>.mo. The runtime library libintl provides functions such as gettext for simple lookups and ngettext for plural forms, along with setlocale, bindtextdomain, and textdomain to control behavior.

The typical workflow uses tools like xgettext to extract strings into a pot template, and msginit/msgmerge to create and update po files. Translators edit the po files, which are then compiled with msgfmt into mo files for use by the program.

gettext is language-agnostic and widely supported through wrappers and bindings across languages, including C, C++, Python, PHP, Perl, and more. It underpins many open-source projects and systems, providing a consistent mechanism for localized user interfaces and enabling scalable collaboration between developers and translators.