Introduction to Unix Chapter 1

Study Notes

An operating system (OS) is a program that starts when a computer is turned on and runs underneath all other programs.
An OS is software that manages a computer system's hardware and software resources, providing a simple virtual machine for users.
Operating systems can be categorized as single-user single-process, single-user multi-process, and multiuser multi-process.

Separates hardware management from applications/programs
Allows applications to work across different hardware platforms
The kernel is the core function of the OS, handling basic-level communication between processes and hardware
Libraries provide standardized access to kernel functions

Developed in the 1970s as a research project at Bell Laboratories
Initially developed as versions 1-6, with characteristics:
- Written in C, with a small subset of code tailored to a target processor
- Released as C source code, allowing modification and improvement
- Designed to allow users to run multiple processes concurrently and connect them with IPC channels

An operating system that is mostly command-based
Distributed under an open-source license
Provides a hierarchical file structure for easier access and maintenance of data
Foundation of modern Linux and BSD operating systems
Capable of handling multiple user activities simultaneously

Comprised of three parts: kernel, shell, and other programs
Kernel is the heart of the Unix operating system, allocating system resources and coordinating computer internals
Shell is a program that processes user requests, interpreting commands and calling programs
Application programs provide additional functionality

Portable: works on different hardware platforms
Open-source: source code is freely available and community-based
Multi-user: allows multiple users to access system resources
Multiprogramming: allows multiple applications to run simultaneously
Hierarchical file system: provides a standard file structure
Shell: provides a command-line interface for executing commands
Security: provides user security using authentication features
Excellent networking environment: provides programs and utilities for networked applications