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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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WC(1P) POSIX Programmer's Manual WC(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.
wc — word, line, and byte or character count
wc [-c|-m] [-lw] [file...]
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.
The wc 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 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.
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.
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.
The input files may be of any type.
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.1‐2017, 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 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.
Default.
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.
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 -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
None.
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.1‐2017 should not break many historical applications (and do
not break any historical conforming applications).
None.
cksum(1p)
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
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 WC(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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