количество слов, строк и байтов или символов (word, line, and byte or character count)
Пролог (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.
Имя (Name)
wc — word, line, and byte or character count
Синопсис (Synopsis)
wc [-c|-m] [-lw] [file...]
Описание (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.
Параметры (Options)
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.
Операнды (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.
Стандартный ввод (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.
Входные файлы (Input files)
The input files may be of any type.
Переменные окружения (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.1‐2017, 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.
Асинхронные события (Asynchronous events)
Default.
Стандартный вывод (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.
Стандартный вывод сообщений (Stderr)
The standard error shall be used only for diagnostic messages.
Выходные файлы (Output files)
None.
Расширенное описание (Extended description)
None.
Статус выхода (Exit)
The following exit values shall be returned:
0 Successful completion.
>0 An error occurred.
Последствия ошибок (Consequences of errors)
Default.
The following sections are informative.
Использование в приложениях (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
Примеры (Examples)
None.
Обоснование (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.1‐2017 should not break many historical
applications (and do not break any historical conforming
applications).
Будущие направления (Future directions)
None.
Смотри также (See also)
cksum(1p)
The Base Definitions volume of POSIX.1‐2017, Chapter 8,
Environment Variables, Section 12.2, Utility Syntax Guidelines
