All I/O Is File I/O
Continuing with the theme of simplification, let's think about the fundamentals of process I/O and the UNIX kernel. The UNIX kernel is charged with policing all forms of I/O as part of its resource management duties. To simplify this task, UNIX has reduced all types of I/O to the level of file I/O. By representing all external devices as files, the system needs only one type of access-control mechanism. This is the infamous “rwx rwx rwx,” user group and other (or UGO) security model presented in all introductory-level UNIX training courses and books. UNIX basically follows the KISS (keep it simple, stupid) principle of design.
Abstraction: A Fundamental of Kernel Design
How is an external tape drive or the key on a keyboard ...
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