In 1982, AT&T produced a short documentary about UNIX. It features Ken Thompson, Dennis Ritchie, Brian Kernighan, and others explaining what they built and, more importantly, why they built it the way they did. Over forty years later, the film remains one of the clearest articulations of systems design thinking I’ve encountered.

I recommend watching the documentary. It is unpretentious, and technical, qualities that are as rare and valuable now as they were in 1982.

Small, Sharp Tools

The central idea of UNIX is composition. Small programs, each doing one thing well, connected through a universal interface: the pipe. This wasn’t just an engineering convenience. It was a philosophy about managing complexity.

In security engineering, we face the same problem at a different scale. Complex systems are hard to reason about. Complex systems are hard to secure. The instinct to build monolithic solutions, a single platform that handles authentication, authorization, logging, alerting, and compliance, creates exactly the kind of opacity that attackers exploit.

The UNIX approach suggests an alternative: build smaller, well-defined components with clear boundaries. Make the interfaces explicit. Let the pieces be inspected, replaced, and composed independently.

One of the things that strikes me about the documentary is how much emphasis the designers placed on being able to see what the system was doing. Text as the universal format. Human-readable configuration. Tools that could be chained together to answer questions about the system’s own behavior.

This is the foundation of security observability. Before we had the term, UNIX had the practice. ps, ls, grep, awk, find: these are instruments for understanding a running system. The principle that a system should be inspectable by its operators is one of the most security-relevant design decisions you can make.

Durability of Good Design

Perhaps the most remarkable thing about UNIX is its longevity. The ideas in this 1982 documentary describe an approach that still works. Not because the technology hasn’t changed (it has, profoundly) but because the design principles were sound.

When I think about building a security program at a company experiencing rapid growth, I think about this kind of durability. The specific tools and vendors will change. The compliance frameworks will evolve. The threat landscape will shift. What endures are the structural decisions: how you decompose problems, where you draw boundaries, what you make visible, and what you make composable.

UNIX teaches that lesson better than most textbooks on the subject.