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PROLOG | NAME | SYNOPSIS | DESCRIPTION | OPTIONS | OPERANDS | STDIN | INPUT FILES | ENVIRONMENT VARIABLES | ASYNCHRONOUS EVENTS | STDOUT | STDERR | OUTPUT FILES | EXTENDED DESCRIPTION | EXIT STATUS | CONSEQUENCES OF ERRORS | APPLICATION USAGE | EXAMPLES | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
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ICONV(1P) POSIX Programmer's Manual ICONV(1P)
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.
iconv — codeset conversion
iconv [-cs] -f frommap -t tomap [file...]
iconv -f fromcode [-cs] [-t tocode] [file...]
iconv -t tocode [-cs] [-f fromcode] [file...]
iconv -l
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.
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.
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.
The standard input shall be used only if no file operands are
specified, or if a file operand is '-'.
The input file shall be a text file.
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.
Default.
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.
The standard error shall be used only for diagnostic messages.
None.
None.
The following exit values shall be returned:
0 Successful completion.
>0 An error occurred.
Default.
The following sections are informative.
The user must ensure that both charmap files use the same symbolic
names for characters the two codesets have in common.
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
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.
None.
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
Portions of this text are reprinted and reproduced in electronic
form from IEEE Std 1003.1-2017, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The
Open Group Base Specifications Issue 7, 2018 Edition, Copyright
(C) 2018 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 .
Any typographical or formatting errors that appear in this page
are most likely to have been introduced during the conversion of
the source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2017 ICONV(1P)
Pages that refer to this page: gencat(1p)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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