530 lines
16 KiB
Groff
530 lines
16 KiB
Groff
.\" $NetBSD: nls.7,v 1.13 2007/03/02 20:28:54 wiz Exp $
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.\"
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.\" Copyright (c) 2003 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed to The NetBSD Foundation
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.\" by Gregory McGarry.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the NetBSD
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.\" Foundation, Inc. and its contributors.
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.\" 4. Neither the name of The NetBSD Foundation nor the names of its
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.\" contributors may be used to endorse or promote products derived
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.\" from this software without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd February 21, 2007
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.Dt NLS 7
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.Os
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.Sh NAME
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.Nm NLS
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.Nd Native Language Support Overview
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.Sh DESCRIPTION
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Native Language Support (NLS) provides commands for a single
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worldwide operating system base.
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An internationalized system has no built-in assumptions or dependencies
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on language-specific or cultural-specific conventions such as:
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.Pp
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.Bl -bullet -offset indent -compact
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.It
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Character classifications
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.It
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Character comparison rules
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.It
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Character collation order
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.It
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Numeric and monetary formatting
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.It
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Date and time formatting
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.It
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Message-text language
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.It
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Character sets
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.El
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.Pp
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All information pertaining to cultural conventions and language is
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obtained at program run time.
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.Pp
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.Dq Internationalization
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(often abbreviated
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.Dq i18n )
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refers to the operation by which system software is developed to support
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multiple cultural-specific and language-specific conventions.
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This is a generalization process by which the system is untied from
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calling only English strings or other English-specific conventions.
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.Dq Localization
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(often abbreviated
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.Dq l10n )
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refers to the operations by which the user environment is customized to
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handle its input and output appropriate for specific language and cultural
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conventions.
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This is a specialization process, by which generic methods already
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implemented in an internationalized system are used in specific ways.
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The formal description of cultural conventions for some country, together
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with all associated translations targeted to the native language, is
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called the
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.Dq locale .
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.Pp
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.Nx
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provides extensive support to programmers and system developers to
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enable internationalized software to be developed.
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.Nx
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also supplies a large variety of locales for system localization.
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.Ss Localization of Information
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All locale information is accessible to programs at run time so that
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data is processed and displayed correctly for specific cultural
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conventions and language.
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.Pp
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A locale is divided into categories.
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A category is a group of language-specific and culture-specific conventions
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as outlined in the list above.
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ISO C specifies the following six standard categories supported by
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.Nx :
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.Pp
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.Bl -tag -compact -width LC_MONETARYXX
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.It Ev LC_COLLATE
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string-collation order information
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.It Ev LC_CTYPE
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character classification, case conversion, and other character attributes
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.It Ev LC_MESSAGES
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the format for affirmative and negative responses
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.It Ev LC_MONETARY
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rules and symbols for formatting monetary numeric information
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.It Ev LC_NUMERIC
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rules and symbols for formatting nonmonetary numeric information
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.It Ev LC_TIME
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rules and symbols for formatting time and date information
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.El
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.Pp
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Localization of the system is achieved by setting appropriate values
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in environment variables to identify which locale should be used.
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The environment variables have the same names as their respective
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locale categories.
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Additionally, the
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.Ev LANG ,
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.Ev LC_ALL ,
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and
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.Ev NLSPATH
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environment variables are used.
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The
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.Ev NLSPATH
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environment variable specifies a colon-separated list of directory names
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where the message catalog files of the NLS database are located.
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The
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.Ev LC_ALL
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and
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.Ev LANG
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environment variables also determine the current locale.
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.Pp
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The values of these environment variables contains a string format as:
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.Pp
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.Bd -literal
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language[_territory][.codeset][@modifier]
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.Ed
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.Pp
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Valid values for the language field come from the ISO639 standard which
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defines two-character codes for many languages.
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Some common language codes are:
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.Pp
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.nf
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.ta \w'SERBO-CROATIAN'u+2n +\w'DE'u+5n +\w'OCEANIC/INDONESIAN'u+2nC
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\fILanguage Name\fP \fICode\fP \fILanguage Family\fP
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.ta \w'SERBO-CROATIAN'u+2n +\w'DE'u+5n +\w'OCEANIC/INDONESIAN'u+2nC
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.sp 5p
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ABKHAZIAN AB IBERO-CAUCASIAN
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AFAN (OROMO) OM HAMITIC
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AFAR AA HAMITIC
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AFRIKAANS AF GERMANIC
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ALBANIAN SQ INDO-EUROPEAN (OTHER)
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AMHARIC AM SEMITIC
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ARABIC AR SEMITIC
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ARMENIAN HY INDO-EUROPEAN (OTHER)
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ASSAMESE AS INDIAN
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AYMARA AY AMERINDIAN
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AZERBAIJANI AZ TURKIC/ALTAIC
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BASHKIR BA TURKIC/ALTAIC
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BASQUE EU BASQUE
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BENGALI BN INDIAN
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BHUTANI DZ ASIAN
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BIHARI BH INDIAN
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BISLAMA BI
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BRETON BR CELTIC
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BULGARIAN BG SLAVIC
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BURMESE MY ASIAN
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BYELORUSSIAN BE SLAVIC
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CAMBODIAN KM ASIAN
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CATALAN CA ROMANCE
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CHINESE ZH ASIAN
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CORSICAN CO ROMANCE
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CROATIAN HR SLAVIC
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CZECH CS SLAVIC
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DANISH DA GERMANIC
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DUTCH NL GERMANIC
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ENGLISH EN GERMANIC
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ESPERANTO EO INTERNATIONAL AUX.
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ESTONIAN ET FINNO-UGRIC
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FAROESE FO GERMANIC
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FIJI FJ OCEANIC/INDONESIAN
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FINNISH FI FINNO-UGRIC
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FRENCH FR ROMANCE
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FRISIAN FY GERMANIC
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GALICIAN GL ROMANCE
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GEORGIAN KA IBERO-CAUCASIAN
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GERMAN DE GERMANIC
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GREEK EL LATIN/GREEK
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GREENLANDIC KL ESKIMO
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GUARANI GN AMERINDIAN
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GUJARATI GU INDIAN
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HAUSA HA NEGRO-AFRICAN
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HEBREW HE SEMITIC
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HINDI HI INDIAN
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HUNGARIAN HU FINNO-UGRIC
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ICELANDIC IS GERMANIC
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INDONESIAN ID OCEANIC/INDONESIAN
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INTERLINGUA IA INTERNATIONAL AUX.
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INTERLINGUE IE INTERNATIONAL AUX.
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INUKTITUT IU
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INUPIAK IK ESKIMO
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IRISH GA CELTIC
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ITALIAN IT ROMANCE
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JAPANESE JA ASIAN
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JAVANESE JV OCEANIC/INDONESIAN
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KANNADA KN DRAVIDIAN
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KASHMIRI KS INDIAN
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KAZAKH KK TURKIC/ALTAIC
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KINYARWANDA RW NEGRO-AFRICAN
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KIRGHIZ KY TURKIC/ALTAIC
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KURUNDI RN NEGRO-AFRICAN
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KOREAN KO ASIAN
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KURDISH KU IRANIAN
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LAOTHIAN LO ASIAN
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LATIN LA LATIN/GREEK
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LATVIAN LV BALTIC
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LINGALA LN NEGRO-AFRICAN
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LITHUANIAN LT BALTIC
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MACEDONIAN MK SLAVIC
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MALAGASY MG OCEANIC/INDONESIAN
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MALAY MS OCEANIC/INDONESIAN
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MALAYALAM ML DRAVIDIAN
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MALTESE MT SEMITIC
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MAORI MI OCEANIC/INDONESIAN
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MARATHI MR INDIAN
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MOLDAVIAN MO ROMANCE
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MONGOLIAN MN
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NAURU NA
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NEPALI NE INDIAN
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NORWEGIAN NO GERMANIC
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OCCITAN OC ROMANCE
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ORIYA OR INDIAN
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PASHTO PS IRANIAN
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PERSIAN (farsi) FA IRANIAN
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POLISH PL SLAVIC
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PORTUGUESE PT ROMANCE
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PUNJABI PA INDIAN
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QUECHUA QU AMERINDIAN
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RHAETO-ROMANCE RM ROMANCE
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ROMANIAN RO ROMANCE
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RUSSIAN RU SLAVIC
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SAMOAN SM OCEANIC/INDONESIAN
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SANGHO SG NEGRO-AFRICAN
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SANSKRIT SA INDIAN
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SCOTS GAELIC GD CELTIC
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SERBIAN SR SLAVIC
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SERBO-CROATIAN SH SLAVIC
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SESOTHO ST NEGRO-AFRICAN
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SETSWANA TN NEGRO-AFRICAN
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SHONA SN NEGRO-AFRICAN
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SINDHI SD INDIAN
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SINGHALESE SI INDIAN
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SISWATI SS NEGRO-AFRICAN
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SLOVAK SK SLAVIC
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SLOVENIAN SL SLAVIC
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SOMALI SO HAMITIC
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SPANISH ES ROMANCE
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SUNDANESE SU OCEANIC/INDONESIAN
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SWAHILI SW NEGRO-AFRICAN
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SWEDISH SV GERMANIC
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TAGALOG TL OCEANIC/INDONESIAN
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TAJIK TG IRANIAN
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TAMIL TA DRAVIDIAN
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TATAR TT TURKIC/ALTAIC
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TELUGU TE DRAVIDIAN
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THAI TH ASIAN
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TIBETAN BO ASIAN
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TIGRINYA TI SEMITIC
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TONGA TO OCEANIC/INDONESIAN
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TSONGA TS NEGRO-AFRICAN
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TURKISH TR TURKIC/ALTAIC
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TURKMEN TK TURKIC/ALTAIC
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TWI TW NEGRO-AFRICAN
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UIGUR UG
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UKRAINIAN UK SLAVIC
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URDU UR INDIAN
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UZBEK UZ TURKIC/ALTAIC
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VIETNAMESE VI ASIAN
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VOLAPUK VO INTERNATIONAL AUX.
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WELSH CY CELTIC
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WOLOF WO NEGRO-AFRICAN
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XHOSA XH NEGRO-AFRICAN
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YIDDISH YI GERMANIC
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YORUBA YO NEGRO-AFRICAN
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ZHUANG ZA
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ZULU ZU NEGRO-AFRICAN
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.ta
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.fi
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.Pp
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For example, the locale for the Danish language spoken in Denmark
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using the ISO 8859-1 character set is da_DK.ISO8859-1.
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The da stands for the Danish language and the DK stands for Denmark.
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The short form of da_DK is sufficient to indicate this locale.
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.Pp
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The environment variable settings are queried by their priority level
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in the following manner:
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.Pp
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.Bl -bullet
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.It
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If the
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.Ev LC_ALL
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environment variable is set, all six categories use the locale it
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specifies.
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.It
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If the
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.Ev LC_ALL
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environment variable is not set, each individual category uses the
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locale specified by its corresponding environment variable.
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.It
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If the
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.Ev LC_ALL
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environment variable is not set, and a value for a particular
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.Ev LC_*
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environment variable is not set, the value of the
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.Ev LANG
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environment variable specifies the default locale for all categories.
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Only the
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.Ev LANG
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environment variable should be set in /etc/profile, since it makes it
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most easy for the user to override the system default using the individual
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.Ev LC_*
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variables.
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.It
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If the
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.Ev LC_ALL
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environment variable is not set, a value for a particular
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.Ev LC_*
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environment variable is not set, and the value of the
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.Ev LANG
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environment variable is not set, the locale for that specific
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category defaults to the C locale.
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The C or POSIX locale assumes the ASCII character set and defines
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information for the six categories.
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.El
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.Ss Character Sets
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A character is any symbol used for the organization, control, or
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representation of data.
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A group of such symbols used to describe a
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particular language make up a character set.
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It is the encoding values in a character set that provide
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the interface between the system and its input and output devices.
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.Pp
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The following character sets are supported in
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.Nx :
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.Bl -tag -width ISO_8859_family
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.It ASCII
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The American Standard Code for Information Exchange (ASCII) standard
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specifies 128 Roman characters and control codes, encoded in a 7-bit
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character encoding scheme.
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.It ISO 8859 family
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Industry-standard character sets specified by the ISO/IEC 8859
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standard.
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The standard is divided into 15 numbered parts, with each
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part specifying broad script similarities.
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Examples include Western European, Central European, Arabic, Cyrillic,
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Hebrew, Greek, and Turkish.
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The character sets use an 8-bit character encoding scheme which is
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compatible with the ASCII character set.
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.It Unicode
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The Unicode character set is the full set of known abstract characters of
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all real-world scripts. It can be used in environments where multiple
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scripts must be processed simultaneously.
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Unicode is compatible with ISO 8859-1 (Western European) and ASCII.
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Many character encoding schemes are available for Unicode, including UTF-8,
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UTF-16 and UTF-32.
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These encoding schemes are multi-byte encodings.
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The UTF-8 encoding scheme uses 8-bit, variable-width encodings which is
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compatible with ASCII.
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The UTF-16 encoding scheme uses 16-bit, variable-width encodings.
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The UTF-32 encoding scheme using 32-bit, fixed-width encodings.
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.El
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.Ss Font Sets
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A font set contains the glyphs to be displayed on the screen for a
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corresponding character in a character set.
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A display must support a suitable font to display a character set.
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If suitable fonts are available to the X server, then X clients can
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include support for different character sets.
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.Xr xterm 1
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includes support for Unicode with UTF-8 encoding.
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.Xr xfd 1
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is useful for displaying all the characters in an X font.
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.Pp
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The
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.Nx
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.Xr wscons 4
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console provides support for loading fonts using the
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.Xr wsfontload 8
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utility.
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Currently, only fonts for the ISO8859-1 family of character sets are
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supported.
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.Ss Internationalization for Programmers
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To facilitate translations of messages into various languages and to
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make the translated messages available to the program based on a
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user's locale, it is necessary to keep messages separate from the
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programs and provide them in the form of message catalogs that a
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program can access at run time.
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.Pp
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Access to locale information is provided through the
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.Xr setlocale 3
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and
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.Xr nl_langinfo 3
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interfaces.
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See their respective man pages for further information.
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.Pp
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Message source files containing application messages are created by
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the programmer and converted to message catalogs.
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These catalogs are used by the application to retrieve and display
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messages, as needed.
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.Pp
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.Nx
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supports two message catalog interfaces: the X/Open
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.Xr catgets 3
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interface and the Uniforum
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.Xr gettext 3
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interface.
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The
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.Xr catgets 3
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interface has the advantage that it belongs to a standard which is
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well supported.
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Unfortunately the interface is complicated to use and
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maintenance of the catalogs is difficult.
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The implementation also doesn't support different character sets.
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The
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.Xr gettext 3
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interface has not been standardized yet, however it is being supported
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by an increasing number of systems.
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It also provides many additional tools which make programming and
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catalog maintenance much easier.
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.Ss Support for Multi-byte Encodings
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Some character sets with multi-byte encodings may be difficult to decode,
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or may contain state (i.e., adjacent characters are dependent).
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ISO C specifies a set of functions using 'wide characters' which can handle
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multi-byte encodings properly.
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The behaviour of these functions is affected
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by the
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.Ev LC_CTYPE
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category of the current locale.
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.Pp
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A wide character is specified in ISO C
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as being a fixed number of bits wide and is stateless.
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There are two types for wide characters:
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.Em wchar_t
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and
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.Em wint_t .
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.Em wchar_t
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is a type which can contain one wide character and operates like 'char'
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type does for one character.
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.Em wint_t
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can contain one wide character or WEOF (wide EOF).
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.Pp
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There are functions that operate on
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.Em wchar_t ,
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and substitute for functions operating on 'char'.
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See
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.Xr wmemchr 3
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and
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.Xr towlower 3
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for details.
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There are some additional functions that operate on
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.Em wchar_t .
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See
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.Xr wctype 3
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and
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.Xr wctrans 3
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for details.
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.Pp
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Wide characters should be used for all I/O processing which may rely
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on locale-specific strings.
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The two primary issues requiring special use of wide characters are:
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.Bl -bullet -offset indent
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.It
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|
All I/O is performed using multibyte characters.
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|
Input data is converted into wide characters immediately after
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|
reading and data for output is converted from wide characters to
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multi-byte encoding immediately before writing.
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Conversion is controlled by the
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.Xr mbstowcs 3 ,
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.Xr mbsrtowcs 3 ,
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.Xr wcstombs 3 ,
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.Xr wcsrtombs 3 ,
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.Xr mblen 3 ,
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.Xr mbrlen 3 ,
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and
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.Xr mbsinit 3 .
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.It
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Wide characters are used directly for I/O, using
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.Xr getwchar 3 ,
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.Xr fgetwc 3 ,
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.Xr getwc 3 ,
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|
.Xr ungetwc 3 ,
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.Xr fgetws 3 ,
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.Xr putwchar 3 ,
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.Xr fputwc 3 ,
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.Xr putwc 3 ,
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and
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.Xr fputws 3 .
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They are also used for formatted I/O functions for wide characters
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such as
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.Xr fwscanf 3 ,
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.Xr wscanf 3 ,
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.Xr swscanf 3 ,
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.Xr fwprintf 3 ,
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.Xr wprintf 3 ,
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.Xr swprintf 3 ,
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.Xr vfwprintf 3 ,
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.Xr vwprintf 3 ,
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and
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.Xr vswprintf 3 ,
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and wide character identifier of %lc, %C, %ls, %S for conventional
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formatted I/O functions.
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.El
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.Sh SEE ALSO
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.Xr gencat 1 ,
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.Xr xfd 1 ,
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.Xr xterm 1 ,
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.Xr catgets 3 ,
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.Xr gettext 3 ,
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.Xr nl_langinfo 3 ,
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.Xr setlocale 3 ,
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.Xr wsfontload 8
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.Sh BUGS
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This man page is incomplete.
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