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Unix Doesn’t Follow the Unix Philosophy

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Unix Doesn’t Follow the Unix Philosophy

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The Unix philosophy is a noble idea, but even Unix doesn’t follow it too closely. The Unix philosophy, as summarized by Doug McIlroy, says

  1. Write programs that do one thing and do it well.
  2. Write programs to work together.
  3. Write programs to handle text streams, because that is a universal interface.

Here is an example from James Hague where the first point has been strained.

The UNIX ls utility seemed like a good idea at the time. It’s the poster child for the UNIX way: a small tool that does exactly one thing well. Here that thing is to display a list of filenames. But deciding exactly what filenames to display and in what format led to the addition of over 35 command-line switches. Now the man page for the BSD version of ls bears the shame of this footnote: “To maintain backward compatibility, the relationships between the many options are quite complex.”

James Hague gives this as only one small example of how programmers have allowed things to become unnecessarily complicated. He concludes

We did this. We who claim to value simplicity are the guilty party. See, all those little design decisions actually matter, and there were places where we could have stopped and said “no, don’t do this.” And even if we were lazy and didn’t do the right thing when changes were easy, before there were thousands of users, we still could have gone back and fixed things later. But we didn’t.

He’s right, to some extent. But as I argued in Where the Unix philosophy breaks down, some of the growth in complexity is understandable. It’s a lot easier to maintain an orthogonal design when your software isn’t being used. Software that gets used becomes less orthogonal and develops diagonal shortcuts.

Why does ls have dozens of tangled options? Because users, even Unix users, are not overly fond of the first two points of the Unix philosophy. They don’t want to chain little programs together. They’d rather do more with the tool at hand than put it down to pick up new tools. They do appreciate the ideal of single-purpose tools that work well together, but only in moderation.

I agree that “all those little design decisions actually matter, and there were places where we could have stopped and said ‘no, don’t do this.’” Some complexity has come from a lack of foresight or a lack of courage. But not all of it. Some of it has come from satisfying what complex humans want from their software.

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