Cypher - An Operating System

Minimal Linux-based operating systems provide a practical environment for examining how user-space components interact with the kernel, but mainstream operating systems often obscure these fundamentals behind complex subsystems. Custom shells offer a clearer view of command interpretation by exposing the fundamental stages without inherited complexity. This paper presents Cypher, a Linux-based operating system designed with its own command interpreter called Rayshell, that demonstrates the basic stages of command processing, including lexical analysis, parsing, expansion and execution. The objective is not to reproduce the completeness or complexity of full-featured operating systems, but to demonstrate a clear, instructive design suitable for research, experimentation and educational use.