LANG and LANGUAGE environment variable in Debian based systems

It seems both the LANG and LANGUAGE environment variable are used by some programs to determine their user interface language.

What are the exact semantics of these variables and where can I read about their correct usage? The manpage for locale(1) only mentions the LC_* family of environment variables. Additionally there is also an LC_ALL variable commonly in place which isn't described there either.

aef

Posted 2012-02-21T17:34:18.770

Reputation: 1 052

Answers

LANG contain the setting for all categories that are not directly set by a LC_* variable.

LC_ALL is used to override every LC_* and LANG and LANGUAGE. It should not be set in a normal user environment, but can be useful when you are writing a script that depend on the precise output of an internationalized command.

LANGUAGE is used to set messages languages (as LC_MESSAGES) to a multi-valued value, e.g., setting it to fr:de:en will use French messages where they exist; if not, it will use German messages, and will fall back to English if neither German nor French messages are available.

Rémi

Posted 2012-02-21T17:34:18.770

Reputation: 1 300

1@Rémi can you elaborate on why LC_ALL should not be used? – Édouard Lopez – 2016-02-02T12:21:34.833

1Not much to say. You have more flexibility if you set LANG than if you set LC_ALL: you can set LANG to something and LC_COLLATE to some other thing. If you set LC_ALL, every other configuration are hidden. – Rémi – 2016-02-03T22:35:15.560

2I don't think LC_ALL overrides LANGUAGE:

they have different meanings (order [e.g.: fr:de:en] vs. characteristics[e.g.: fr_FR])

2018-06-06T15:11:49.787

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The GNU getText documentation's chapter Specifying a Priority List of Languages states: gettext gives preference to LANGUAGE over LC_ALL and LANG. Additionally, the chapter Locale Environment Variables states: 1. LANGUAGE 2. LC_ALL [...]

– Murmel – 2018-06-13T12:25:28.383

1Where can I find documentation about LANGUAGE? Is it mutually exclusive to LC_MESSAGES? – aef – 2012-02-22T00:44:29.797

Everything is in the locale(7) manpage. LC_MESSAGES changes the language messages are displayed in and what an affirmative or negative answer looks like. The GNU C-library contains the gettext(3), ngettext(3), and rpmatch(3) functions to ease the use of these information. The GNU gettext family of functions also obey the environment variable LANGUAGE (containing a colon-separated list of locales) if the category is set to a valid locale other than "C". – Rémi – 2012-02-24T15:08:40.907

Have a look at the manpage locale(7): it describes that LANG is a fallback setting, while LC_ALL overrides all separate LC_* settings.

Jaap Eldering

Posted 2012-02-21T17:34:18.770

Reputation: 7 596

3man 7 locale is the command – Smile4ever – 2017-01-08T15:52:35.577

For reference, the locale system is GNU GetText, which has its full documentation available in the gettext-doc package (Debian/Ubuntu).

Alternatively, there is an online manual with authoritative and elaborate documentation of the LANG and LANGUAGE environment variables.

mikini

Posted 2012-02-21T17:34:18.770

Reputation: 41