UNIX Architecture

UNIX Architecture is layer-based, meaning each layer has a specific role and interacts with others in a structured way.

🔹 Layers of UNIX Architecture

1️⃣ Hardware

• Physical components like CPU, memory, disk, keyboard, mouse
• UNIX does not allow users to access hardware directly

2️⃣ Kernel (Heart of UNIX)

• Core part of UNIX
• Manages system resources

Main functions of Kernel:

• 🧠 Process management
• 💾 Memory management
• 📂 File system management
• 🔌 Device management
• 🔐 Security & access control

➡️ Kernel acts as a bridge between hardware and users

3️⃣ Shell (Command Interpreter)

• Interface between user and kernel
• Takes user commands and passes them to the kernel

Examples of shells:

• sh (Bourne Shell)
• bash (Bourne Again Shell)
• csh, ksh

Example command:

ls

4️⃣ Utilities / Commands

• Programs that perform tasks
• Examples:
  • ls → list files
  • cp → copy files
  • rm → delete files
  • cat → display file content

5️⃣ Users

• End users interact with the system using the shell
• Can be:
  • Normal user
  • Super user (root)

🔁 Working Flow of UNIX Architecture

User → Shell → Kernel → Hardware

✅ Advantages of UNIX Architecture

• Modular and well-structured
• Secure and stable
• Supports multi-user & multitasking
• Easy to maintain and extend