The system is, to a very large extent, internationalized and can be flexibly modified for local needs. In other words, internationalization (I18N) allows specific localizations (L10N). The abbreviations I18N and L10N are derived from the first and last letters of the words and, in between, the number of letters omitted.
Settings are made with LC_ variables defined in
the file /etc/sysconfig/language. This refers not
only to native language support, but also to the
categories Messages (Language), Character
Set, Sort Order, Time and
Date, Numbers and
Money. Each of these categories can be defined
directly with its own variable or indirectly with a master variable in the
file language (see the locale man
page).
RC_LC_MESSAGES,
RC_LC_CTYPE,
RC_LC_COLLATE,
RC_LC_TIME,
RC_LC_NUMERIC,
RC_LC_MONETARY
These variables are passed to the shell without the
RC_ prefix and represent the listed
categories. The shell profiles concerned are listed below. The current
setting can be shown with the command locale.
RC_LC_ALL
This variable, if set, overwrites the values of the variables already mentioned.
RC_LANG
If none of the previous variables are set, this is the fallback. By
default, only RC_LANG is set. This makes it
easier for users to enter their own values.
ROOT_USES_LANG
A yes or no variable. If set to
no, root
always works in the POSIX environment.
The variables can be set with the YaST sysconfig editor (see Section 16.3.1, “Changing the System Configuration Using the YaST sysconfig Editor”). The value of such a variable contains the language code, country code, encoding and modifier. The individual components are connected by special characters:
LANG=<language>[[_<COUNTRY>].<Encoding>[@<Modifier>]]
You should always set the language and country codes together. Language settings follow the standard ISO 639 available at http://www.evertype.com/standards/iso639/iso639-en.html and http://www.loc.gov/standards/iso639-2/. Country codes are listed in ISO 3166 available at http://www.din.de/gremien/nas/nabd/iso3166ma/codlstp1/en_listp1.html.
It only makes sense to set values for which usable description files can
be found in /usr/lib/locale. Additional description
files can be created from the files in
/usr/share/i18n using the command
localedef. The description files are part of the
glibc-i18ndata package. A description file for
en_US.UTF-8 (for English and United States) can be
created with:
localedef -i en_US -f UTF-8 en_US.UTF-8
LANG=en_US.UTF-8
This is the default setting if American English is selected during installation. If you selected another language, that language is enabled but still with UTF-8 as the character encoding.
LANG=en_US.ISO-8859-1
This sets the language to English, country to United States and the
character set to ISO-8859-1. This character set
does not support the Euro sign, but it can be useful sometimes for
programs that have not been updated to support
UTF-8. The string defining the charset
(ISO-8859-1 in this case) is then evaluated by
programs like Emacs.
LANG=en_IE@euro
The above example explicitly includes the Euro sign in a language setting. This setting is basically obsolete now, as UTF-8 also covers the Euro symbol. It is only useful if an application supports ISO-8859-15 and not UTF-8.
SuSEconfig reads the variables in
/etc/sysconfig/language and writes the necessary
changes to /etc/SuSEconfig/profile and
/etc/SuSEconfig/csh.cshrc.
/etc/SuSEconfig/profile is read or
sourced by /etc/profile.
/etc/SuSEconfig/csh.cshrc is sourced by
/etc/csh.cshrc. This makes the settings available
systemwide.
Users can override the system defaults by editing their
~/.bashrc accordingly. For instance, if you do not
want to use the systemwide en_US for program messages,
include LC_MESSAGES=es_ES so that messages are
displayed in Spanish instead.
If you are not satisfied with locale system defaults, change the settings
in ~/.i18n according to the Bash scripting syntax.
Entries in ~/.i18n override system defaults from
/etc/sysconfig/language. Use the same variable names
but without the RC_ namespace prefixes. For example,
use LANG instead of RC_LANG:
LANG=cs_CZ.UTF-8 LC_COLLATE=C
Files in the category Messages are, as a rule, only
stored in the corresponding language directory (like
en) to have a fallback. If you set
LANG to en_US and the message
file in /usr/share/locale/en_US/LC_MESSAGES does not
exist, it falls back to
/usr/share/locale/en/LC_MESSAGES.
A fallback chain can also be defined, for example, for Breton to French or for Galician to Spanish to Portuguese:
LANGUAGE="br_FR:fr_FR"
LANGUAGE="gl_ES:es_ES:pt_PT"
If desired, use the Norwegian variants Nynorsk and Bokmål instead (with
additional fallback to no):
LANG="nn_NO"
LANGUAGE="nn_NO:nb_NO:no"
or
LANG="nb_NO"
LANGUAGE="nb_NO:nn_NO:no"
Note that in Norwegian, LC_TIME is also treated
differently.
One problem that can arise is a separator used to delimit groups of
digits not being recognized properly. This occurs if
LANG is set to only a two-letter language code
like de, but the definition file glibc uses is located
in /usr/share/lib/de_DE/LC_NUMERIC. Thus
LC_NUMERIC must be set to
de_DE to make the separator definition visible to the
system.
The GNU C Library Reference Manual, Chapter
“Locales and Internationalization”. It is included in
glibc-info.
Markus Kuhn, UTF-8 and Unicode FAQ for Unix/Linux, currently at http://www.cl.cam.ac.uk/~mgk25/unicode.html.
Unicode-Howto, by Bruno Haible:
/usr/share/doc/howto/en/txt/Unicode-HOWTO.gz
(package howto).