
\S filter \S

A filter is a program that reads input, transforms it, and writes some
output.  Filters are different from "editors"\S*\S and other commands because
filters do not change the contents of a file.  Examples of filters are
grep(1) and tail(1) which select and print part of the input, sort(1) which
sorts the input, and wc(1) which counts the number of words in the input.
sed(1) and awk(1) are also filters but they are called programmable filters
or data transformers because you write a program that transforms the input.

\S*\S defined in the \Sglossary\S
