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Copyright 2007 Osamu Aoki GPL, (Please agree to GPL, GPL2, and any version of GPL which is compatible with DSFG if you update any part of wiki page)

The I18N and L10N

The international support for the application software is done in 2 steps:

Here, I18N stands for "internationalization" and L10N stands for "localization". (There are 18 and 10 letters between I and N or L and N.)

The modern software such as Gnome and KDE which are written to handle [http://en.wikipedia.org/wiki/UTF-8 UTF-8 ]data and to provide their message through the gettext(1) infrastructure are multilingualized and can be localized simply by setting pertinent environment variables to the appropriate locale if the corresponding translated message packages are installed.

The simplest representation of the text data is ASCII which is sufficient for English and uses 7 bits. In order to support more characters beyond 7 bits limit for international support, many character encoding systems have been invented. The modern and sensible encoding system is UTF-8 which can handle practically all the characters known to the human (see: @{@thebasicsofencoding@}@).

The international hardware support is enabled with localized hardware configuration data.

The keyboard input

The Debian system can be configured to work with many international keyboard arrangements:

List of keyboard reconfiguration methods.

environment

command

Linux console

dpkg-reconfigure --priority=low console-data

X Window

dpkg-reconfigure --priority=low xserver-xorg

This will support keyboard input for accented characters of many European languages with its dead-key function. For Asian languages, you need more complicated input method support such as scim discussed next.

The input method support with scim

Setup of multilingual input for the Debian system is simplified by using the SCIM family of packages with the im-switch package. The list of SCIM packages are:

List of input method supports with scim.

1

2

package

popcon

locale

scim-anthy

9

Japanese

scim-canna

5

, ,

scim-skk

2

, ,

scim-prime

0

, ,

scim-tables-ja

*133

, , (not useful)

scim-uim

*65

, ,

scim-tables-zh

*388

Chinese (for zh_*)

scim-pinyin

*333

, , (for zh_CN)

scim-chewing

*177

, , (for zh_TW)

scim-uim

*65

Korean

scim-hangul

*54

, ,

scim-tables-ko

*43

, ,

scim-m17n

*95

Indic, Arabic and others

scim-tables-additional

*92

, ,

scim-uim

*65

, ,

scim-thai

*23

Thai

The kinput2 method and other locale dependent Asian classic input methods still exist but are not recommended for the modern UTF-8 X environment. The uim tool chain is an alternative approach for the international input method for the modern UTF-8 X environment which is also capable for non-X environment.

An example for Japanese

I find the Japanese input method started under English environment (en_US.UTF-8) very useful. Here is how I did it with SCIM.

(!) In order to start SCIM under the non-CJK and non-en_US locale, you need to add list of those locales in UTF-8 to the ~/.scim/global or /etc/scim/global file as:

/SupportedUnicodeLocales = en_US.UTF-8,en_GB.UTF_8,fr_FR.UTF-8

Please note:

For the detail of setup, see /usr/share/doc/im-switch/README.Debian.gz, /usr/share/doc/scim/README.Debian.gz or /usr/share/doc/uim/README.Debian.gz. Here key points are described.

Disabling the input method

If you wish to input without going through XIM, set XMODIFIERS value to "none" while starting a program. This may be the case if you use Japanese input infrastructure egg on emacs. From shell, execute as:

$ XMODIFIERS=none emacs

In order to adjust the command executed by the Debian menu, place customized configuration in /etc/menu following method described in /usr/share/doc/menu/html .

The display output

Linux console can only display limited characters. (You need to use special terminal program such as jfbterm to display non-European languages on the non-X console.)

X Window can display any characters in the UTF-8 as long as required font data exists. (The encoding of the original font data is taken care by the X Window system and transparent to the user.)

The locale

The following locale discussion will focus on the UTF-8 compatible setting and simple configuration using the environment variable LANG only. I assume that X Window is started from the gdm for simplicity, here. See locale(1) manpage if you wish more complicated locale setup.

The reconfiguration of the locale

In order for the system to access a particular locale, the locale data must be compiled from the locale database. (The Debian system does not come with all available locales pre-compiled unless you installed the locales-all package.) The full list of supported locales available for compiling are listed in /usr/share/i18n/SUPPORTED. This lists all the proper locale names. The following will list all the available UTF-8 locales already compiled to the binary form:

$ locale -a

The following command execution will reconfigure locale package:

# dpkg-reconfigure locales

When updating the list of available locales, please make sure to chose all interesting language ones with UTF-8 codeset only.

Configuring system with LANG

The environment variable LANG (see: @{@langvariable@}@) is:

{i} It is good idea to install system wide default locale as "en_US.UTF-8" while chosing more specific locale via gdm menu. This way, you can always access functioning character terminal with readable messages even when X Window system is not working. This becomes essential for languages which use non-roman characters such as Chinese, Japanese, and Korean.

The gdm program localization via PAM

When starting the X session with gdm, you can select the locale for the X session from its menu independent of the system default locale value in the /etc/defaults/locale. The only X program which can not be localized by the gdm is the gdm program itself. This requires PAM customization (see: @{@pamandnss@}@) as follows.

First, change the following line defining language environment variable in /etc/pam.d/gdm or /etc/pam.d/gdm-autologin (the actual file depends on the display manager and its setup):

auth    required        pam_env.so read_env=1 envfile=/etc/default/locale

into

auth    required        pam_env.so read_env=1 envfile=/etc/default/locale-gdm

Then create a /etc/defaults/locale-gdm file with -rw-r--r-- 1 root root permission containing, eg. for Japanese message:

LANG="ja_JP.UTF-8"

and keep the default /etc/defaults/locale file for other programs being:

LANG="en_US.UTF-8"

Filename encoding

The mount(8) command may assume some file system (e.g. vfat) to be non-UTF-8 encoding while mounting them without mount option. The UTF-8 support in such case can be enabled by providing explicit mount option.

(!) When auto-mounting hot-pluggable USB memory stick under modern desktop environment such as Gnome, you may provide such mount option by right clicking the icon on the desktop, click "Drive" tab, click to expand "Setting", and entering "utf8" to "Mount options:". The next time this memory stick is mounted, mount with UTF-8 is enabled.

(!) If you are upgrading system or moving disk drives from older non-UTF-8 system, file names with non-ascii characters may be encoded in the historic and deprecated encodings such as "ISO-8859-1" or "eucJP". Please seek help of text conversion tools to convert them to "UTF-8". See: @{@thetextdataconversiontools@}@ .

Localizing messages and documentation

Translations exist for many of the text messages and documents that are displayed in the Debian system, such as error messages, standard program output, menus, and manual pages.

The aptitude list under "Tasks" -> "Localization" provide extensive list of useful packages for localizing messages and documentation.

For example, you can obtain the localized message for manpage by installing the manpages-<LANG>. To read the Italian-language manpage for <programname>, execute

LANG=it_IT.UTF-8 man <programname>

to read it from /usr/share/man/it/.