преобразование кодового набора (codeset conversion)
Пролог (Prolog)
This manual page is part of the POSIX Programmer's Manual. The
Linux implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
Имя (Name)
iconv — codeset conversion
Синопсис (Synopsis)
iconv [-cs] -f frommap -t tomap [file...]
iconv -f fromcode [-cs] [-t tocode] [file...]
iconv -t tocode [-cs] [-f fromcode] [file...]
iconv -l
Описание (Description)
The iconv utility shall convert the encoding of characters in
file from one codeset to another and write the results to
standard output.
When the options indicate that charmap files are used to specify
the codesets (see OPTIONS), the codeset conversion shall be
accomplished by performing a logical join on the symbolic
character names in the two charmaps. The implementation need not
support the use of charmap files for codeset conversion unless
the POSIX2_LOCALEDEF symbol is defined on the system.
Параметры (Options)
The iconv utility shall conform to the Base Definitions volume of
POSIX.1‐2017, Section 12.2, Utility Syntax Guidelines.
The following options shall be supported:
-c Omit any characters that are invalid in the codeset of
the input file from the output. When -c is not used,
the results of encountering invalid characters in the
input stream (either those that are not characters in
the codeset of the input file or that have no
corresponding character in the codeset of the output
file) shall be specified in the system documentation.
The presence or absence of -c shall not affect the exit
status of iconv.
-f fromcodeset
Identify the codeset of the input file. The
implementation shall recognize the following two forms
of the fromcodeset option-argument:
fromcode The fromcode option-argument must not contain
a <slash> character. It shall be interpreted
as the name of one of the codeset
descriptions provided by the implementation
in an unspecified format. Valid values of
fromcode are implementation-defined.
frommap The frommap option-argument must contain a
<slash> character. It shall be interpreted as
the pathname of a charmap file as defined in
the Base Definitions volume of POSIX.1‐2017,
Section 6.4, Character Set Description File.
If the pathname does not represent a valid,
readable charmap file, the results are
undefined.
If this option is omitted, the codeset of the current
locale shall be used.
-l Write all supported fromcode and tocode values to
standard output in an unspecified format.
-s Suppress any messages written to standard error
concerning invalid characters. When -s is not used, the
results of encountering invalid characters in the input
stream (either those that are not valid characters in
the codeset of the input file or that have no
corresponding character in the codeset of the output
file) shall be specified in the system documentation.
The presence or absence of -s shall not affect the exit
status of iconv.
-t tocodeset
Identify the codeset to be used for the output file.
The implementation shall recognize the following two
forms of the tocodeset option-argument:
tocode The semantics shall be equivalent to the -f
fromcode option.
tomap The semantics shall be equivalent to the -f
frommap option.
If this option is omitted, the codeset of the current
locale shall be used.
If either -f or -t represents a charmap file, but the other does
not (or is omitted), or both -f and -t are omitted, the results
are undefined.
Операнды (Operands)
The following operand shall be supported:
file A pathname of an input file. If no file operands are
specified, or if a file operand is '-', the standard
input shall be used.
Стандартный ввод (Stdin)
The standard input shall be used only if no file operands are
specified, or if a file operand is '-'.
Входные файлы (Input files)
The input file shall be a text file.
Переменные окружения (Environment variables)
The following environment variables shall affect the execution of
iconv:
LANG Provide a default value for the internationalization
variables that are unset or null. (See the Base
Definitions volume of POSIX.1‐2017, Section 8.2,
Internationalization Variables for the precedence of
internationalization variables used to determine the
values of locale categories.)
LC_ALL If set to a non-empty string value, override the values
of all the other internationalization variables.
LC_CTYPE Determine the locale for the interpretation of
sequences of bytes of text data as characters (for
example, single-byte as opposed to multi-byte
characters in arguments). During translation of the
file, this variable is superseded by the use of the
fromcode option-argument.
LC_MESSAGES
Determine the locale that should be used to affect the
format and contents of diagnostic messages written to
standard error.
NLSPATH Determine the location of message catalogs for the
processing of LC_MESSAGES.
Асинхронные события (Asynchronous events)
Default.
Стандартный вывод (Stdout)
When the -l option is used, the standard output shall contain all
supported fromcode and tocode values, written in an unspecified
format.
When the -l option is not used, the standard output shall contain
the sequence of characters read from the input files, translated
to the specified codeset. Nothing else shall be written to the
standard output.
Стандартный вывод сообщений (Stderr)
The standard error shall be used only for diagnostic messages.
Выходные файлы (Output files)
None.
Расширенное описание (Extended description)
None.
Статус выхода (Exit)
The following exit values shall be returned:
0 Successful completion.
>0 An error occurred.
Последствия ошибок (Consequences of errors)
Default.
The following sections are informative.
Использование в приложениях (Application usage)
The user must ensure that both charmap files use the same
symbolic names for characters the two codesets have in common.
Примеры (Examples)
The following example converts the contents of file mail.x400
from the ISO/IEC 6937:2001 standard codeset to the
ISO/IEC 8859‐1:1998 standard codeset, and stores the results in
file mail.local:
iconv -f IS6937 -t IS8859 mail.x400 > mail.local
Обоснование (Rationale)
The iconv utility can be used portably only when the user
provides two charmap files as option-arguments. This is because a
single charmap provided by the user cannot reliably be joined
with the names in a system-provided character set description.
The valid values for fromcode and tocode are implementation-
defined and do not have to have any relation to the charmap
mechanisms. As an aid to interactive users, the -l option was
adopted from the Plan 9 operating system. It writes information
concerning these implementation-defined values. The format is
unspecified because there are many possible useful formats that
could be chosen, such as a matrix of valid combinations of
fromcode and tocode. The -l option is not intended for shell
script usage; conforming applications will have to use charmaps.
The iconv utility may support the conversion between ASCII and
EBCDIC-based encodings, but is not required to do so. In an XSI-
compliant implementation, the dd utility is the only method
guaranteed to support conversion between these two character
sets.
Будущие направления (Future directions)
None.
Смотри также (See also)
dd(1p), gencat(1p)
The Base Definitions volume of POSIX.1‐2017, Section 6.4,
Character Set Description File, Chapter 8, Environment Variables,
Section 12.2, Utility Syntax Guidelines
