7.6 Filters

The classic notion of filter in Unix-like systems and other Operating Systems is of a program that reads certain input using its standard input, realized some transformations on it, and writes the result on its standard output. The filter doesn’t need to operate on all the data at once, nor to buffer it: it reads input in chunks once it becomes available and is needed, and write output as necessary.

GNU poke provides the so called stream IO spaces in order to implement binary utilities that act like filters.