System Management Concepts: Operating System and Devices

Understanding Locale

A locale is made up of the language, territory, and code set combination used to identify a set of language conventions. These conventions include information on collation, case conversion, and character classification, the language of message catalogs, date-and-time representation, the monetary symbol, and numeric representation.

Locale information contained in locale definition source files must first be converted into a locale database by the localedef command. The setlocale subroutine can then access this information and set locale information for applications. To deal with locale data in a logical manner, locale definition source files are divided into six categories (see Understanding Locale Categories). Each category contains a specific aspect of the locale data. The LC_* environment variables and the LANG environment variable can be used in specifying the desired locale.

Locale Naming Conventions

Each locale is named by its locale definition source file name. These files are named for the language, territory, and code set information they describe. The following format is used for naming a locale definition file:

language[_territory][.codeset][@modifier]

For example, the locale for the Danish language spoken in Denmark using the ISO8859-1 code set is da_DK.ISO8859-1. The da stands for the Danish language and the DK stands for Denmark. The short form of da_DK is sufficient to indicate this locale. The same language and territory using the IBM-850 code set is indicated by either Da_DK.IBM-850 or the short form Da_DK.

System-defined locale definition files are provided to show the format of locale categories and their keywords. The /usr/lib/nls/loc directory contains the locale definition files for system-defined locales. The C, or POSIX, locale defines the ANSI C-defined standard locale inherited by all processes at startup time. The other system-defined locale definition source files are:

Installation Default Locale

The installation default locale refers to the locale selected at installation. For example, when prompted, a user can specify the French language as spoken in Canada during the installation process. The code set automatically defaults to the ISO8859-1 code set. With this information, the system sets the value of the default locale, specified by the LANG environment variable, to fr_CA (fr for ISO8859-1 French and CA for Canada). Every process uses this locale unless the LC_* or LANG environment variables are modified. The default locale can be changed by using the Manage Language Environment menu in the System Management Interface Tool (SMIT) Overview.