The Unix file and the intermodal container both represent format-agnostic, standardized interfaces that enabled revolutionary levels of interoperability.
Malcolm McLean's shipping containers standardized physical cargo handling by making the contents irrelevant to the transportation system—a 20-foot or 40-foot steel box with standard corner fittings could contain anything and move seamlessly across ships, trains, and trucks.
In 1969 Ken Thompson implemented Unix files as formatless byte streams — a universal envelope that didn't require declaring type or size at file creation. Unix files standardized data handling by making the contents irrelevant to the system — files moved seamlessly through pipes, filters, and programs. See AT&T engineer Catherine Ann Brooks describe the system in 1982: https://youtu.be/XvDZLjaCJuw?si=CesJuFNqUYATWSyr&t=667
Both innovations solved similar problems: the proliferation of incompatible formats that prevented efficient composition and transfer. Before shipping containers, different cargo types required specialized handling and couldn't easily transfer between transportation modes. Before Unix's byte stream abstraction, different file formats required specialized programs and couldn't easily compose through pipelines. Both solutions involved imposing a universal, neutral interface that pushed format-specific knowledge to the edges of the system.
Both innovations achieved transformative results, and both required ecosystem-wide adoption to realize their full value.
Footnote: Docker Inc. analogizes its containers to the intermodal container. The metaphor is apt, but arguably, the Unix file was more transformative.
2025-11-10