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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.
NAME
wc — word, line, and byte or character count
SYNOPSIS
wc [−c|−m] [−lw] [file...]
DESCRIPTION
The wc utility shall read one or more input files and, by default, write the number of <newline>
characters, words, and bytes contained in each input file to the standard output.
The utility also shall write a total count for all named files, if more than one input file is specified.
The wc utility shall consider a word to be a non-zero-length string of characters delimited by white
space.
OPTIONS
The wc utility shall conform to the Base Definitions volume of POSIX.1‐2008, Section 12.2, Utility Syntax
Guidelines.
The following options shall be supported:
−c Write to the standard output the number of bytes in each input file.
−l Write to the standard output the number of <newline> characters in each input file.
−m Write to the standard output the number of characters in each input file.
−w Write to the standard output the number of words in each input file.
When any option is specified, wc shall report only the information requested by the specified options.
OPERANDS
The following operand shall be supported:
file A pathname of an input file. If no file operands are specified, the standard input shall be
used.
STDIN
The standard input shall be used if no file operands are specified, and shall be used if a file operand
is '−' and the implementation treats the '−' as meaning standard input. Otherwise, the standard input
shall not be used. See the INPUT FILES section.
INPUT FILES
The input files may be of any type.
ENVIRONMENT VARIABLES
The following environment variables shall affect the execution of wc:
LANG Provide a default value for the internationalization variables that are unset or null. (See the
Base Definitions volume of POSIX.1‐2008, 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 and input files) and
which characters are defined as white-space characters.
LC_MESSAGES
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.
NLSPATH Determine the location of message catalogs for the processing of LC_MESSAGES.
ASYNCHRONOUS EVENTS
Default.
STDOUT
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>
If the −m option is specified, the number of characters shall replace the <bytes> field in this format.
If any options are specified and the −l option is not specified, the number of <newline> characters shall
not be written.
If any options are specified and the −w option is not specified, the number of words shall not be
written.
If any options are specified and neither −c nor −m is specified, the number of bytes or characters shall
not be written.
If no input file operands are specified, no name shall be written and no <blank> characters preceding the
pathname shall be written.
If more than one input file operand is specified, an additional line shall be written, of the same format
as the other lines, except that the word total (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.
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 −m option is not a switch, but an option at the same level as −c. Thus, to produce the full default
output with character counts instead of bytes, the command required is:
wc −mlw
EXAMPLES
None.
RATIONALE
The output file format pseudo-printf() string differs from the System V version of wc:
"%7d%7d%7d %s\n"
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 <space>, <tab>, and <newline> as word separators. The equivalent
of the ISO C standard isspace() function is more appropriate.
The −c 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 −m option (reminiscent of ``multi-byte'') was added to obtain actual character counts.
Early proposals only specified the results when input files were text files. The current specification
more closely matches historical practice. (Bytes, words, and <newline> characters are counted separately
and the results are written when an end-of-file is detected.)
Historical implementations of the wc utility only accepted one argument to specify the options −c, −l,
and −w. 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.1‐2008
should not break many historical applications (and do not break any historical conforming applications).
FUTURE DIRECTIONS
None.
SEE ALSO
cksum
The Base Definitions volume of POSIX.1‐2008, Chapter 8, Environment Variables, Section 12.2, Utility
Syntax Guidelines
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2013 Edition,
Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of Electrical and Electronics Engineers, Inc
and The Open Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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.unix.org/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 .