Unlocking the Basics: How Computers and Linux Work Inside

1. Computer Composition and Functions

Computers consist of a hardware system and a software system. The hardware includes the central processing unit (CPU), memory, and input/output (I/O) devices, which together form the three core components of an electronic computer.

CPU

The CPU contains an arithmetic‑logic unit (ALU) and general‑purpose registers for arithmetic and logical operations. The controller fetches, decodes, and issues control signals to other components to execute instructions.

Memory

Memory stores programs and data. Internal memory (RAM) is fast, directly accessible by the CPU via the system bus. External memory (hard disks, USB drives, optical discs) is slower and accessed indirectly.

I/O Devices

Input devices (mouse, keyboard, scanner, microphone) bring data into memory; output devices (monitor, speaker, printer) present data to users. All external devices communicate with the CPU through interfaces and the system bus.

2. Software System – Operating System

An operating system (OS) manages hardware and software resources and serves as the kernel of a computer system. It handles memory management, resource scheduling, I/O control, networking, file systems, and provides a user interface.

Typical OS structure: Kernel + Applications.

Key OS functions:

Prevent uncontrolled hardware access by applications.

Provide a uniform mechanism for applications to control complex hardware.

Standard PC OS responsibilities include process management, memory management, file system, networking, security, user interface, and device drivers.

3. Linux Distributions

Linux’s open‑source kernel and applications allow many organizations to create their own distributions. Over 100 variants exist, including Debian, Slackware, Red Hat, Gentoo, Arch, and Red Flag Linux.

Three major branches are Debian (e.g., Ubuntu Server), Red Hat (e.g., RHEL, CentOS, Fedora), and Slackware (e.g., openSUSE). Differences are mainly in package management: RPM‑based (rpm) versus DEB‑based (deb) systems.

4. Linux Philosophy

Everything is a file.

Build small, single‑purpose programs.

Minimize interactive prompts; automate with scripts.

Store configuration in plain text.

5. Command Syntax and Common Commands

General format: #COMMAND [OPTIONS] [ARGUMENTS]. Short options use a single dash (e.g., -l), long options use double dashes (e.g., --help).

ifconfig : view and configure network interfaces (options -a, -s).

echo : display a line of text.

tty : show the current terminal device.

startx : launch the graphical interface from a virtual terminal.

export : set or display environment variables ( -f, -n, -p).

pwd : print the working directory ( -L, -P, --help).

history : list previously executed commands; !!, !n, !string recall specific entries.

shutdown , poweroff , reboot : safely halt, power off, or restart the system with various options.

hwclock and date : view or set hardware and system time ( --set‑date, --version, -s, -w).

6. Getting Help for Commands

Commands are either built‑in (provided by the shell) or external executables. Help can be obtained with: help COMMAND for built‑ins. COMMAND --help or COMMAND -h for external commands. man COMMAND to read the manual pages located in /usr/share/man. info COMMAND for GNU online documentation.

Search engines, README files, official documentation, and distribution resources.

The man command organizes pages into eight sections covering user commands, system calls, library functions, special files, file formats, games, miscellaneous, and system administration.

7. Linux Filesystem Hierarchy

The Filesystem Hierarchy Standard (FHS) defines a tree‑like directory structure rooted at /. Standard top‑level directories include /bin, /etc, /home, /var, /usr, etc., each serving specific purposes.