mirror of https://github.com/mkerrisk/man-pages
401 lines
13 KiB
Groff
401 lines
13 KiB
Groff
.\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
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.\" and Copyright (C) 2014 Michael Kerrisk <mtk.manpages@gmail.com>
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.\"
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.\" %%%LICENSE_START(VERBATIM)
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\" %%%LICENSE_END
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.\"
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.\" Modified Sat Jul 24 17:28:34 1993 by Rik Faith <faith@cs.unc.edu>
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.\" Modified Sun Jun 01 17:16:34 1997 by Jochen Hein
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.\" <jochen.hein@delphi.central.de>
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.\" Modified Thu Apr 25 00:43:19 2002 by Bruno Haible <bruno@clisp.org>
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.\"
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.TH LOCALE 7 2017-09-15 "Linux" "Linux Programmer's Manual"
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.SH NAME
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locale \- description of multilanguage support
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.SH SYNOPSIS
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.nf
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.B #include <locale.h>
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.fi
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.SH DESCRIPTION
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A locale is a set of language and cultural rules.
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These cover aspects
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such as language for messages, different character sets, lexicographic
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conventions, and so on.
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A program needs to be able to determine its locale
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and act accordingly to be portable to different cultures.
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.PP
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The header
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.I <locale.h>
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declares data types, functions and macros which are useful in this
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task.
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.PP
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The functions it declares are
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.BR setlocale (3)
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to set the current locale, and
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.BR localeconv (3)
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to get information about number formatting.
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.PP
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There are different categories for locale information a program might
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need; they are declared as macros.
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Using them as the first argument
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to the
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.BR setlocale (3)
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function, it is possible to set one of these to the desired locale:
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.TP
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.BR LC_ADDRESS " (GNU extension, since glibc 2.2)"
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.\" See ISO/IEC Technical Report 14652
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Change settings that describe the formats (e.g., postal addresses)
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used to describe locations and geography-related items.
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Applications that need this information can use
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.BR nl_langinfo (3)
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to retrieve nonstandard elements, such as
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.B _NL_ADDRESS_COUNTRY_NAME
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(country name, in the language of the locale)
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and
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.B _NL_ADDRESS_LANG_NAME
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(language name, in the language of the locale),
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which return strings such as "Deutschland" and "Deutsch"
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(for German-language locales).
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(Other element names are listed in
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.IR <langinfo.h> .)
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.TP
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.B LC_COLLATE
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This category governs the collation rules used for
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sorting and regular expressions,
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including character equivalence classes and
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multicharacter collating elements.
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This locale category changes the behavior of the functions
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.BR strcoll (3)
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and
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.BR strxfrm (3),
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which are used to compare strings in the local alphabet.
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For example,
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the German sharp s is sorted as "ss".
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.TP
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.B LC_CTYPE
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This category determines the interpretation of byte sequences as characters
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(e.g., single versus multibyte characters), character classifications
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(e.g., alphabetic or digit), and the behavior of character classes.
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On glibc systems, this category also determines
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the character transliteration rules for
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.BR iconv (1)
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and
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.BR iconv (3).
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It changes the behavior of the character handling and
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classification functions, such as
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.BR isupper (3)
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and
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.BR toupper (3),
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and the multibyte character functions such as
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.BR mblen (3)
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or
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.BR wctomb (3).
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.TP
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.BR LC_IDENTIFICATION " (GNU extension, since glibc 2.2)"
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.\" See ISO/IEC Technical Report 14652
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Change settings that relate to the metadata for the locale.
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Applications that need this information can use
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.BR nl_langinfo (3)
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to retrieve nonstandard elements, such as
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.B _NL_IDENTIFICATION_TITLE
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(title of this locale document)
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and
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.B _NL_IDENTIFICATION_TERRITORY
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(geographical territory to which this locale document applies),
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which might return strings such as "English locale for the USA"
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and "USA".
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(Other element names are listed in
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.IR <langinfo.h> .)
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.TP
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.B LC_MONETARY
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This category determines the formatting used for
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monetary-related numeric values.
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This changes the information returned by
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.BR localeconv (3),
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which describes the way numbers are usually printed, with details such
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as decimal point versus decimal comma.
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This information is internally
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used by the function
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.BR strfmon (3).
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.TP
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.B LC_MESSAGES
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This category affects the language in which messages are displayed
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and what an affirmative or negative answer looks like.
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The GNU C library contains the
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.BR gettext (3),
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.BR ngettext (3),
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and
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.BR rpmatch (3)
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functions to ease the use of this information.
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The GNU gettext family of
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functions also obey the environment variable
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.BR LANGUAGE
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(containing a colon-separated list of locales)
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if the category is set to a valid locale other than
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.BR """C""" .
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This category also affects the behavior of
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.BR catopen (3).
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.TP
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.BR LC_MEASUREMENT " (GNU extension, since glibc 2.2)"
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Change the settings relating to the measurement system in the locale
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(i.e., metric versus US customary units).
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Applications can use
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.BR nl_langinfo (3)
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to retrieve the nonstandard
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.B _NL_MEASUREMENT_MEASUREMENT
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element, which returns a pointer to a character
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that has the value 1 (metric) or 2 (US customary units).
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.TP
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.BR LC_NAME " (GNU extension, since glibc 2.2)"
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.\" See ISO/IEC Technical Report 14652
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Change settings that describe the formats used to address persons.
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Applications that need this information can use
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.BR nl_langinfo (3)
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to retrieve nonstandard elements, such as
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.B _NL_NAME_NAME_MR
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(general salutation for men)
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and
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.B _NL_NAME_NAME_MS
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(general salutation for women)
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elements, which return strings such as "Herr" and "Frau"
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(for German-language locales).
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(Other element names are listed in
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.IR <langinfo.h> .)
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.TP
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.B LC_NUMERIC
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This category determines the formatting rules used for nonmonetary
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numeric values\(emfor example,
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the thousands separator and the radix character
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(a period in most English-speaking countries,
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but a comma in many other regions).
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It affects functions such as
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.BR printf (3),
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.BR scanf (3),
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and
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.BR strtod (3).
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This information can also be read with the
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.BR localeconv (3)
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function.
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.TP
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.BR LC_PAPER " (GNU extension, since glibc 2.2)"
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.\" See ISO/IEC Technical Report 14652
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Change the settings relating to the dimensions of the standard paper size
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(e.g., US letter versus A4).
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Applications that need the dimensions can obtain them by using
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.BR nl_langinfo (3)
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to retrieve the nonstandard
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.B _NL_PAPER_WIDTH
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and
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.B _NL_PAPER_HEIGHT
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elements, which return
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.I int
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values specifying the dimensions in millimeters.
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.TP
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.BR LC_TELEPHONE " (GNU extension, since glibc 2.2)"
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.\" See ISO/IEC Technical Report 14652
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Change settings that describe the formats to be used with telephone services.
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Applications that need this information can use
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.BR nl_langinfo (3)
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to retrieve nonstandard elements, such as
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.B _NL_TELEPHONE_INT_PREFIX
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(international prefix used to call numbers in this locale),
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which returns a string such as "49" (for Germany).
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(Other element names are listed in
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.IR <langinfo.h> .)
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.TP
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.B LC_TIME
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This category governs the formatting used for date and time values.
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For example, most of Europe uses a 24-hour clock versus the
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12-hour clock used in the United States.
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The setting of this category affects the behavior of functions such as
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.BR strftime (3)
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and
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.BR strptime (3).
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.TP
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.B LC_ALL
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All of the above.
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.PP
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If the second argument to
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.BR setlocale (3)
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is an empty string,
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.BR """""" ,
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for the default locale, it is determined using the following steps:
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.IP 1. 3
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If there is a non-null environment variable
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.BR LC_ALL ,
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the value of
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.B LC_ALL
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is used.
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.IP 2.
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If an environment variable with the same name as one of the categories
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above exists and is non-null, its value is used for that category.
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.IP 3.
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If there is a non-null environment variable
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.BR LANG ,
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the value of
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.B LANG
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is used.
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.PP
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Values about local numeric formatting is made available in a
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.I struct lconv
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returned by the
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.BR localeconv (3)
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function, which has the following declaration:
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.PP
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.in +4n
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.EX
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struct lconv {
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/* Numeric (nonmonetary) information */
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char *decimal_point; /* Radix character */
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char *thousands_sep; /* Separator for digit groups to left
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of radix character */
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char *grouping; /* Each element is the number of digits in
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a group; elements with higher indices
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are further left. An element with value
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CHAR_MAX means that no further grouping
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is done. An element with value 0 means
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that the previous element is used for
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all groups further left. */
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/* Remaining fields are for monetary information */
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char *int_curr_symbol; /* First three chars are a currency
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symbol from ISO 4217. Fourth char
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is the separator. Fifth char
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is \(aq\\0\(aq. */
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char *currency_symbol; /* Local currency symbol */
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char *mon_decimal_point; /* Radix character */
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char *mon_thousands_sep; /* Like \fIthousands_sep\fP above */
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char *mon_grouping; /* Like \fIgrouping\fP above */
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char *positive_sign; /* Sign for positive values */
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char *negative_sign; /* Sign for negative values */
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char int_frac_digits; /* International fractional digits */
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char frac_digits; /* Local fractional digits */
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char p_cs_precedes; /* 1 if currency_symbol precedes a
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positive value, 0 if succeeds */
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char p_sep_by_space; /* 1 if a space separates
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currency_symbol from a positive
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value */
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char n_cs_precedes; /* 1 if currency_symbol precedes a
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negative value, 0 if succeeds */
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char n_sep_by_space; /* 1 if a space separates
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currency_symbol from a negative
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value */
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/* Positive and negative sign positions:
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0 Parentheses surround the quantity and currency_symbol.
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1 The sign string precedes the quantity and currency_symbol.
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2 The sign string succeeds the quantity and currency_symbol.
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3 The sign string immediately precedes the currency_symbol.
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4 The sign string immediately succeeds the currency_symbol. */
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char p_sign_posn;
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char n_sign_posn;
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};
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.EE
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.in
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.SS POSIX.1-2008 extensions to the locale API
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POSIX.1-2008 standardized a number of extensions to the locale API,
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based on implementations that first appeared in version 2.3
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of the GNU C library.
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These extensions are designed to address the problem that
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the traditional locale APIs do not mix well with multithreaded applications
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and with applications that must deal with multiple locales.
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.PP
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The extensions take the form of new functions for creating and
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manipulating locale objects
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.RB ( newlocale (3),
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.BR freelocale (3),
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.BR duplocale (3),
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and
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.BR uselocale (3))
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and various new library functions with the suffix "_l" (e.g.,
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.BR toupper_l (3))
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that extend the traditional locale-dependent APIs (e.g.,
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.BR toupper (3))
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to allow the specification of a locale object that should apply when
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executing the function.
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.SH ENVIRONMENT
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The following environment variable is used by
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.BR newlocale (3)
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and
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.BR setlocale (3),
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and thus affects all unprivileged localized programs:
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.TP
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.B LOCPATH
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A list of pathnames, separated by colons (\(aq:\(aq),
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that should be used to find locale data.
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If this variable is set,
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only the individual compiled locale data files from
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.I LOCPATH
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and the system default locale data path are used;
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any available locale archives are not used (see
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.BR localedef (1)).
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The individual compiled locale data files are searched for under
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subdirectories which depend on the currently used locale.
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For example, when
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.I en_GB.UTF-8
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is used for a category, the following subdirectories are searched for,
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in this order:
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.IR en_GB.UTF-8 ,
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.IR en_GB.utf8 ,
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.IR en_GB ,
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.IR en.UTF-8 ,
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.IR en.utf8 ,
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and
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.IR en .
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.SH FILES
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.TP
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.I /usr/lib/locale/locale-archive
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Usual default locale archive location.
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.TP
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.I /usr/lib/locale
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Usual default path for compiled individual locale files.
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.SH CONFORMING TO
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POSIX.1-2001.
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.\"
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.\" The GNU gettext functions are specified in LI18NUX2000.
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.SH SEE ALSO
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.BR iconv (1),
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.BR locale (1),
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.BR localedef (1),
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.BR catopen (3),
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.BR gettext (3),
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.BR iconv (3),
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.BR localeconv (3),
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.BR mbstowcs (3),
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.BR newlocale (3),
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.BR ngettext (3),
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.BR nl_langinfo (3),
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.BR rpmatch (3),
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.BR setlocale (3),
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.BR strcoll (3),
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.BR strfmon (3),
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.BR strftime (3),
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.BR strxfrm (3),
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.BR uselocale (3),
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.BR wcstombs (3),
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.BR locale (5),
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.BR charsets (7),
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.BR unicode (7),
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.BR utf-8 (7)
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