Everything is a file (in Linux)

This elegant design principle dates back to the beginning of (Unix) time, a.k.a. the 70s. However, this simple principle is an oversimplification - consider the existence of directories. In reality, the slogan “Everything is a file” is a convenient shorthand for the more accurate but less catchy notion that (almost) all resources available to a process on a Unix-like operating system can be referenced by a file descriptor.