The options -l, -w, and -c or -m may be used in any combination to specify that a subset of newline characters, words, and bytes or characters (respectively) are to be reported. The default options are -lwm.
The order and number of output columns are not affected by the order and number of options. There is always at most one column in the following order: number of newline characters, words, bytes, and filename. The filename is not present if one or no filename is given on the command line.
If more than one filename is given on the command line, the final
line contains the total number of newline characters, words and
bytes in all files, and is labeled with the word
the filename column.
ISO/IEC DIS 99452:1992, Information technology Portable Operating System Interface (POSIX) Part 2: Shell and Utilities (IEEE Std 1003.21992);
AT&T SVID Issue 2;
X/Open CAE Specification, Commands and Utilities, Issue 4, 1992.