Operating systems · 1974 · Dennis M. Ritchie & Ken Thompson

The UNIX Time-Sharing System

Compose a programmable environment from a small set of abstractions: processes, hierarchical files, byte streams, a replaceable shell, redirection, and pipes.

The central move

Compose a programmable environment from a small set of abstractions: processes, hierarchical files, byte streams, a replaceable shell, redirection, and pipes.

Why it had to exist

Operating systems often exposed specialized devices and monolithic user environments. Tool building became expensive when each interface had a different shape.

Where it leads

Small mechanisms → composable tools → portable C and Unix → today’s process and stream interfaces.

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