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Unix philosophy

The Unix philosophy is a set of cultural norms and philosophical approaches to developing software systems based on the experience of leading developers of the Unix operating system. Many individuals have examined these norms and tried to summarize them in some way.

Doug McIlroy, the inventor of Unix pipes and one of the founders of the Unix tradition, summarized the philosophy in A Quarter Century of Unix as follows: "This is the Unix philosophy: Write programs that do one thing and do it well. Write programs to work together. Write programs to handle text streams, because that is a universal interface." This has sometimes been briefly summarized as "Do one thing, do it well."

Rob Pike, a leading expert on applying the C programming language, offers the following "rules" in Notes on C Programming as programming maxims (but they can be easily viewed as points of a Unix philosophy):

Ken Thompson rephrased Pike's rule 4 as, "When in doubt, use brute force".

Richard P. Gabriel suggests that a key advantage of Unix was that it embodied a style of design (a philosophy) he termed Worse is better. In the "Worse is better" design style, simplicity of both the interface and the implementation is more important than any other attribute of the system (including correctness, consistency, and completeness). Gabriel argues that this design style has many key advantages.

Eric S. Raymond, in his book The Art Of Unix Programming, summarizes the Unix philosophy as the widely-used engineering philosophy, "Keep it Simple, Stupid" (KISS). He then describes how he believes this overall philosophy is applied as a cultural Unix norm:

Certainly many of these norms are accepted outside of the Unix community - if not when Unix first used them, at least later on. Also, many of these norms were not unique or originally appearing in the Unix community. Nevertheless, it is true that those who have learned to use Unix at master level tend to accept the combination of all of these philosophical ideas as being the basis of the Unix style.


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