locale(7) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | ENVIRONMENT | FILES | CONFORMING TO | SEE ALSO | COLOPHON

LOCALE(7)               Linux Programmer's Manual              LOCALE(7)

NAME         top

       locale - description of multilanguage support

SYNOPSIS         top

       #include <locale.h>

DESCRIPTION         top

       A locale is a set of language and cultural rules.  These cover
       aspects such as language for messages, different character sets,
       lexicographic conventions, and so on.  A program needs to be able
       to determine its locale and act accordingly to be portable to
       different cultures.

       The header <locale.h> declares data types, functions, and macros
       which are useful in this task.

       The functions it declares are setlocale(3) to set the current
       locale, and localeconv(3) to get information about number
       formatting.

       There are different categories for locale information a program
       might need; they are declared as macros.  Using them as the first
       argument to the setlocale(3) function, it is possible to set one
       of these to the desired locale:

       LC_ADDRESS (GNU extension, since glibc 2.2)
              Change settings that describe the formats (e.g., postal
              addresses) used to describe locations and geography-
              related items.  Applications that need this information
              can use nl_langinfo(3) to retrieve nonstandard elements,
              such as _NL_ADDRESS_COUNTRY_NAME (country name, in the
              language of the locale) and _NL_ADDRESS_LANG_NAME
              (language name, in the language of the locale), which
              return strings such as "Deutschland" and "Deutsch" (for
              German-language locales).  (Other element names are listed
              in <langinfo.h>.)

       LC_COLLATE
              This category governs the collation rules used for sorting
              and regular expressions, including character equivalence
              classes and multicharacter collating elements.  This
              locale category changes the behavior of the functions
              strcoll(3) and strxfrm(3), which are used to compare
              strings in the local alphabet.  For example, the German
              sharp s is sorted as "ss".

       LC_CTYPE
              This category determines the interpretation of byte
              sequences as characters (e.g., single versus multibyte
              characters), character classifications (e.g., alphabetic
              or digit), and the behavior of character classes.  On
              glibc systems, this category also determines the character
              transliteration rules for iconv(1) and iconv(3).  It
              changes the behavior of the character handling and
              classification functions, such as isupper(3) and
              toupper(3), and the multibyte character functions such as
              mblen(3) or wctomb(3).

       LC_IDENTIFICATION (GNU extension, since glibc 2.2)
              Change settings that relate to the metadata for the
              locale.  Applications that need this information can use
              nl_langinfo(3) to retrieve nonstandard elements, such as
              _NL_IDENTIFICATION_TITLE (title of this locale document)
              and _NL_IDENTIFICATION_TERRITORY (geographical territory
              to which this locale document applies), which might return
              strings such as "English locale for the USA" and "USA".
              (Other element names are listed in <langinfo.h>.)

       LC_MONETARY
              This category determines the formatting used for monetary-
              related numeric values.  This changes the information
              returned by localeconv(3), which describes the way numbers
              are usually printed, with details such as decimal point
              versus decimal comma.  This information is internally used
              by the function strfmon(3).

       LC_MESSAGES
              This category affects the language in which messages are
              displayed 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
              this 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".  This category also affects
              the behavior of catopen(3).

       LC_MEASUREMENT (GNU extension, since glibc 2.2)
              Change the settings relating to the measurement system in
              the locale (i.e., metric versus US customary units).
              Applications can use nl_langinfo(3) to retrieve the
              nonstandard _NL_MEASUREMENT_MEASUREMENT element, which
              returns a pointer to a character that has the value 1
              (metric) or 2 (US customary units).

       LC_NAME (GNU extension, since glibc 2.2)
              Change settings that describe the formats used to address
              persons.  Applications that need this information can use
              nl_langinfo(3) to retrieve nonstandard elements, such as
              _NL_NAME_NAME_MR (general salutation for men) and
              _NL_NAME_NAME_MS (general salutation for women) elements,
              which return strings such as "Herr" and "Frau" (for
              German-language locales).  (Other element names are listed
              in <langinfo.h>.)

       LC_NUMERIC
              This category determines the formatting rules used for
              nonmonetary numeric values—for example, the thousands
              separator and the radix character (a period in most
              English-speaking countries, but a comma in many other
              regions).  It affects functions such as printf(3),
              scanf(3), and strtod(3).  This information can also be
              read with the localeconv(3) function.

       LC_PAPER (GNU extension, since glibc 2.2)
              Change the settings relating to the dimensions of the
              standard paper size (e.g., US letter versus A4).
              Applications that need the dimensions can obtain them by
              using nl_langinfo(3) to retrieve the nonstandard
              _NL_PAPER_WIDTH and _NL_PAPER_HEIGHT elements, which
              return int values specifying the dimensions in
              millimeters.

       LC_TELEPHONE (GNU extension, since glibc 2.2)
              Change settings that describe the formats to be used with
              telephone services.  Applications that need this
              information can use nl_langinfo(3) to retrieve nonstandard
              elements, such as _NL_TELEPHONE_INT_PREFIX (international
              prefix used to call numbers in this locale), which returns
              a string such as "49" (for Germany).  (Other element names
              are listed in <langinfo.h>.)

       LC_TIME
              This category governs the formatting used for date and
              time values.  For example, most of Europe uses a 24-hour
              clock versus the 12-hour clock used in the United States.
              The setting of this category affects the behavior of
              functions such as strftime(3) and strptime(3).

       LC_ALL All of the above.

       If the second argument to setlocale(3) is an empty string, "",
       for the default locale, it is determined using the following
       steps:

       1. If there is a non-null environment variable LC_ALL, the value
          of LC_ALL is used.

       2. If an environment variable with the same name as one of the
          categories above exists and is non-null, its value is used for
          that category.

       3. If there is a non-null environment variable LANG, the value of
          LANG is used.

       Values about local numeric formatting is made available in a
       struct lconv returned by the localeconv(3) function, which has
       the following declaration:

           struct lconv {

               /* Numeric (nonmonetary) information */

               char *decimal_point;     /* Radix character */
               char *thousands_sep;     /* Separator for digit groups to left
                                           of radix character */
               char *grouping;     /* Each element is the number of digits in
                                      a group; elements with higher indices
                                      are further left.  An element with value
                                      CHAR_MAX means that no further grouping
                                      is done.  An element with value 0 means
                                      that the previous element is used for
                                      all groups further left. */

               /* Remaining fields are for monetary information */

               char *int_curr_symbol;   /* First three chars are a currency
                                           symbol from ISO 4217.  Fourth char
                                           is the separator.  Fifth char
                                           is '\0'. */
               char *currency_symbol;   /* Local currency symbol */
               char *mon_decimal_point; /* Radix character */
               char *mon_thousands_sep; /* Like thousands_sep above */
               char *mon_grouping;      /* Like grouping above */
               char *positive_sign;     /* Sign for positive values */
               char *negative_sign;     /* Sign for negative values */
               char  int_frac_digits;   /* International fractional digits */
               char  frac_digits;       /* Local fractional digits */
               char  p_cs_precedes;     /* 1 if currency_symbol precedes a
                                           positive value, 0 if succeeds */
               char  p_sep_by_space;    /* 1 if a space separates
                                           currency_symbol from a positive
                                           value */
               char  n_cs_precedes;     /* 1 if currency_symbol precedes a
                                           negative value, 0 if succeeds */
               char  n_sep_by_space;    /* 1 if a space separates
                                           currency_symbol from a negative
                                           value */
               /* Positive and negative sign positions:
                  0 Parentheses surround the quantity and currency_symbol.
                  1 The sign string precedes the quantity and currency_symbol.
                  2 The sign string succeeds the quantity and currency_symbol.
                  3 The sign string immediately precedes the currency_symbol.
                  4 The sign string immediately succeeds the currency_symbol. */
               char  p_sign_posn;
               char  n_sign_posn;
           };

   POSIX.1-2008 extensions to the locale API
       POSIX.1-2008 standardized a number of extensions to the locale
       API, based on implementations that first appeared in version 2.3
       of the GNU C library.  These extensions are designed to address
       the problem that the traditional locale APIs do not mix well with
       multithreaded applications and with applications that must deal
       with multiple locales.

       The extensions take the form of new functions for creating and
       manipulating locale objects (newlocale(3), freelocale(3),
       duplocale(3), and uselocale(3)) and various new library functions
       with the suffix "_l" (e.g., toupper_l(3)) that extend the
       traditional locale-dependent APIs (e.g., toupper(3)) to allow the
       specification of a locale object that should apply when executing
       the function.

ENVIRONMENT         top

       The following environment variable is used by newlocale(3) and
       setlocale(3), and thus affects all unprivileged localized
       programs:

       LOCPATH
              A list of pathnames, separated by colons (':'), that
              should be used to find locale data.  If this variable is
              set, only the individual compiled locale data files from
              LOCPATH and the system default locale data path are used;
              any available locale archives are not used (see
              localedef(1)).  The individual compiled locale data files
              are searched for under subdirectories which depend on the
              currently used locale.  For example, when en_GB.UTF-8 is
              used for a category, the following subdirectories are
              searched for, in this order: en_GB.UTF-8, en_GB.utf8,
              en_GB, en.UTF-8, en.utf8, and en.

FILES         top

       /usr/lib/locale/locale-archive
              Usual default locale archive location.

       /usr/lib/locale
              Usual default path for compiled individual locale files.

CONFORMING TO         top

       POSIX.1-2001.

SEE ALSO         top

       iconv(1), locale(1), localedef(1), catopen(3), gettext(3),
       iconv(3), localeconv(3), mbstowcs(3), newlocale(3), ngettext(3),
       nl_langinfo(3), rpmatch(3), setlocale(3), strcoll(3), strfmon(3),
       strftime(3), strxfrm(3), uselocale(3), wcstombs(3), locale(5),
       charsets(7), unicode(7), utf-8(7)

COLOPHON         top

       This page is part of release 5.13 of the Linux man-pages project.
       A description of the project, information about reporting bugs,
       and the latest version of this page, can be found at
       https://www.kernel.org/doc/man-pages/.

Linux                          2021-03-22                      LOCALE(7)

Pages that refer to this page: locale(1)localectl(1)localedef(1)preconv(1)systemd(1)catopen(3)duplocale(3)isalpha(3)localeconv(3)newlocale(3)nl_langinfo(3)setlocale(3)strerror(3)strfmon(3)toupper(3)towlower(3)towupper(3)uselocale(3)crontab(5)locale(5)locale.conf(5)environ(7)glob(7)system_data_types(7)