Master Linux Locale: Decode LC_* Categories and Configure Your System

In computing, a locale defines the language, territory, and cultural conventions that a program uses at runtime, based on the user's language, country/region, and local traditions.

The locale system divides cultural conventions into twelve major categories, each represented by an LC_ variable:

Language symbols and classification (LC_CTYPE)

Numeric formatting (LC_NUMERIC)

Collation and sorting rules (LC_COLLATE)

Time display format (LC_TIME)

Monetary units (LC_MONETARY)

Message texts such as prompts, errors, and titles (LC_MESSAGES)

Name formatting (LC_NAME)

Address formatting (LC_ADDRESS)

Telephone number formatting (LC_TELEPHONE)

Measurement units (LC_MEASUREMENT)

Paper size defaults (LC_PAPER)

Overview of the locale’s own information (LC_IDENTIFICATION)

Locale definition files (e.g., en_US, zh_CN, de_DE@euro) reside in /usr/share/i18n/locales and are plain‑text files that can be opened with any editor, though much of the content uses Unicode character indexes.

The suffix after “@” in a locale name denotes a modifier; for example, de_DE@euro uses European sorting and comparison conventions, whereas de_DE follows standard German conventions.

A locale string follows the pattern language[_territory][.codeset][@modifier]. Examples include:

zh_CN.GB2312 – Chinese (China) with GB2312 character set.

zh_CN.GB18030 – Chinese (China) with GB18030 character set.

zh_TW.BIG5 – Chinese (Taiwan) with Big5 character set.

en_GB.ISO-8859-1 – English (Great Britain) with ISO‑8859‑1 character set.

de_DE.UTF-8@euro – German (Germany) with UTF‑8 encoding and European modifier.

The most critical category for Chinese input is LC_CTYPE, which defines valid characters, their classifications (uppercase, lowercase, punctuation, etc.), and includes the Unicode class “hanzi” that makes Chinese characters legal in Linux regardless of the underlying codeset.

To set a locale, you assign values to the twelve LC_ variables, or more conveniently to LC_ALL and LANG. Their precedence is LC_ALL > specific LC_* > LANG. For instance, setting LC_ALL=zh_CN.UTF-8 forces all locale categories to use that value, overriding any other settings.

If LC_ALL=zh_CN.UTF-8 , all other LC_* and LANG are ignored.

If LANG=zh_CN.UTF-8 and other LC_* are set to en_US.UTF-8 without LC_ALL , the system uses the specific LC_* values.

If only LANG=zh_CN.UTF-8 is set, all unset LC_* variables default to that value.

If LANG=zh_CN.UTF-8 but LC_CTYPE=en_US.UTF-8 and no LC_ALL , then LC_CTYPE uses the English setting while the remaining categories fall back to LANG .

In summary, to obtain a fully Chinese system, set LC_ALL=zh_CN.* or LANG=zh_CN.*; to keep the interface in English while enabling Chinese input, set LC_CTYPE=zh_CN.* and LANG=en_US.*. If no locale variables are defined, the system defaults to the POSIX “C” locale.

The difference between LANG and LANGUAGE is that LANGUAGE is used by most programs to select the interface language, whereas LANG provides a low‑priority default for all locale‑related variables.