✅ Operating System

 What is an Operating System (OS)?

An Operating System (OS) is system software that manages computer hardware and software resources, providing services for computer programs. It acts as an interface between the user and the hardware.

---

Functions of an Operating System

1. Process Management – Manages running applications (tasks) and system processes.

2. Memory Management – Allocates and manages RAM for efficient performance.

3. File System Management – Organizes, stores, and retrieves files.

4. Device Management – Controls hardware components like printers, keyboards, and storage devices.

5. Security & Access Control – Protects against unauthorized access (user authentication, firewalls, encryption).

6. User Interface (UI) – Provides an interface for users (GUI or command-line).

---

Types of Operating Systems

1. Single-User vs. Multi-User OS

Single-User OS – Used by one person at a time (e.g., Windows, macOS).

Multi-User OS – Supports multiple users simultaneously (e.g., Linux, Unix, Windows Server).

2. Multi-Tasking OS

Runs multiple applications at the same time (e.g., Windows, macOS, Linux).

3. Real-Time OS (RTOS)

Used in critical systems like medical devices, industrial automation, and aerospace (e.g., VxWorks, QNX).

4. Mobile OS

Designed for smartphones and tablets (e.g., Android, iOS).

5. Network OS

Manages network resources and servers (e.g., Windows Server, Linux Server).

-

✅ Unix Operating System

 

Unix Operating System

Unix is a powerful, multi-user, multitasking operating system (OS) originally developed in the 1960s at AT&T Bell Labs by Ken Thompson, Dennis Ritchie, and others. It has influenced many modern operating systems, including Linux, macOS, and BSD.

---

Key Features of Unix:

✔ Multi-user & Multitasking – Supports multiple users and processes simultaneously.

✔ Portability – Can run on various hardware platforms.

✔ Hierarchical File System – Organizes files in directories.

✔ Shell & Command-Line Interface (CLI) – Uses commands for system control.

✔ Security & Permissions – User-based access control.

✔ Networking & Scripting – Built-in networking and automation capabilities.

---

Unix Architecture

Unix is structured into four main layers:

1. Hardware – The physical components (CPU, memory, disks).

2. Kernel – The core of Unix, managing resources and processes.

3. Shell – The command-line interpreter that interacts with the kernel.

4. User Applications – Programs like editors, compilers, and utilities.

---

Popular Unix-Based Operating Systems

✔ macOS (Apple)

✔ Solaris (Oracle)

✔ AIX (IBM)

✔ FreeBSD / OpenBSD / NetBSD

.