Print histogram of character frequencies
freq [ -dxocr ] [ file ... ]
Freq reads the given files (default standard input) and prints histograms of the character frequencies. By default, freq counts each byte as a character; under the -r option it instead counts UTF sequences, that is, runes.
Each non-zero entry of the table is printed preceded by the byte value, in decimal, octal, hex, and Unicode character (if printable). If any options are given, the -d, -x, -o, -c flags specify a subset of value formats: decimal, hex, octal, and character, respectively.
\*9/src/cmd/freq.c
utf(7), wc(1)