↩ 🔵 🔵 🔵 ❪✺❫ Unix Concepts ○ ❪✺₄₀❫ Operating System Sets ○ Unix ○› ❪✺₄❫ GNU Sets ○ ❪✺₄❫ Linux Sets ○ ❪✺_ₛₛ❫ Unix Subsets ○