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.
OPTIONS
The iconv utility shall conform to the Base Definitions volume
of IEEE Std 1003.1-2001, 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 IEEE Std 1003.1-2001,
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 -ffromcode option.
tomap
The semantics shall be equivalent to the tomap 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.
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.
STDIN
The standard input shall be used only if no file operands are
specified, or if a file operand is '-'
.
INPUT FILES
The input file shall be a text file.
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
IEEE Std 1003.1-2001, 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
.
ASYNCHRONOUS EVENTS
Default.
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.
STDERR
The standard error shall be used only for diagnostic messages.
OUTPUT FILES
None.
EXTENDED DESCRIPTION
None.
EXIT STATUS
The following exit values shall be returned:
0
Successful completion.
>0
An error occurred.
CONSEQUENCES OF ERRORS
Default.
The following sections are informative.
APPLICATION USAGE
The user must ensure that both charmap files use the same symbolic
names for characters the two codesets have in common.
EXAMPLES
The following example converts the contents of file mail.x400
from the ISO/IEC 6937:1994 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
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.
FUTURE DIRECTIONS
None.
SEE ALSO
gencat
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .
