wc - word, line, and byte or character count
The wc utility shall read one or more input files and, by default,
write the number of <newline>s, 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
IEEE Std 1003.1-2001, 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
-l Write to the standard output the number of <newline>s in each
-m Write to the standard output the number of characters in each
-w Write to the standard output the number of words in each input
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 only if no file operands are
specified. 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
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.
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
", <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>s 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>s 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.
The following exit values shall be returned:
0 Successful completion.
>0 An error occurred.
CONSEQUENCES OF ERRORS
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:
The output file format pseudo- printf() string differs from the System
V version of wc:
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>s 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 IEEE Std 1003.1-2001 should not break many historical
applications (and do not break any historical conforming applications).
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.php .