wc

The wc utility shall read one or more input files and, by default, write the number of 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. 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 file. 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 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. Provide a default value for the internationalization variables that are unset or null. (See XBD 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. [XSI) ] ![[Option Start]]( Determine the location of message catalogs for the processing of LC MESSAGES. ![[Option End]]( If any options are specified and the -l option is not specified, the number of 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. which produces possibly ambiguous and unparsable results for very large files, as it assumes no number shall exceed six digits. 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 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).