Section: POSIX Programmer's Manual (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.
--- word, line, and byte or character count
wc [-c|-m] [-lw] [file...]
utility shall read one or more input files and, by default, write the
characters, words, and bytes contained in each input file to the standard
The utility also shall write a total count for all named files, if more
than one input file is specified.
utility shall consider a
to be a non-zero-length string of characters delimited by white space.
utility shall conform to the Base Definitions volume of POSIX.1-2017,
, Utility Syntax Guidelines.
The following options shall be supported:
Write to the standard output the number of bytes in each input file.
Write to the standard output the number of
characters in each input file.
Write to the standard output the number of characters in each input
Write to the standard output the number of words in each input file.
When any option is specified,
shall report only the information requested by the specified options.
The following operand shall be supported:
A pathname of an input file. If no
operands are specified, the standard input shall be used.
The standard input shall be used if no
operands are specified, and shall be used if a
and the implementation treats the
as meaning standard input.
Otherwise, the standard input shall not be used.
See the INPUT FILES section.
The input files may be of any type.
The following environment variables shall affect the execution of
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.)
If set to a non-empty string value, override the values of all the
other internationalization variables.
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 and input files) and which
characters are defined as white-space characters.
Determine the locale that should be used to affect the format and
contents of diagnostic messages written to standard error and
informative messages written to standard output.
Determine the location of message catalogs for the processing of
By default, the standard output shall contain an entry for each input
file of the form:
"%d %d %d %s\n", <newlines>, <words>, <bytes>, <file>
option is specified, the number of characters shall replace the
<bytes> field in this format.
If any options are specified and the
option is not specified, the number of
characters shall not be written.
If any options are specified and the
option is not specified, the number of words shall not be written.
If any options are specified and neither
is specified, the number of bytes or characters shall not be written.
If no input
operands are specified, no name shall be written and no
characters preceding the pathname shall be written.
If more than one input
operand is specified, an additional line shall be written, of the same
format as the other lines, except that the word
(in the POSIX locale) shall be written instead of a pathname and the
total of each column shall be written as appropriate. Such an
additional line, if any, is written at the end of the output.
The standard error shall be used only for diagnostic messages.
The following exit values shall be returned:
An error occurred.
CONSEQUENCES OF ERRORS
The following sections are informative.
option is not a switch, but an option at the same level as
Thus, to produce the full default output with character counts instead
of bytes, the command required is:
The output file format pseudo-printf
string differs from the System V version of
which produces possibly ambiguous and unparsable results for very large
files, as it assumes no number shall exceed six digits.
Some historical implementations use only
as word separators. The equivalent of the ISO C standard
function is more appropriate.
option stands for ``character'' count, even though it counts bytes.
This stems from the sometimes erroneous historical view that bytes and
characters are the same size. Due to international requirements, the
option (reminiscent of ``multi-byte'') was added to obtain actual
Early proposals only specified the results when input files were text
files. The current specification more closely matches historical
practice. (Bytes, words, and
characters are counted separately and the results are written when an
end-of-file is detected.)
Historical implementations of the
utility only accepted one argument to specify the options
Some of them also had multiple occurrences of an option cause the
corresponding count to be written multiple times and had the order of
specification of the options affect the order of the fields on output,
but did not document either of these. Because common usage either
specifies no options or only one option, and because none of this was
documented, the changes required by this volume of POSIX.1-2017 should not break many
historical applications (and do not break any historical conforming
The Base Definitions volume of POSIX.1-2017,
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
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