What is Linux

Linux

An open-source operating system modeled on UNIX, freely available, and a multiuser system.

Founder

Linus Torvalds, who created Linux in 1991.

Kernel

The core program of an operating system that manages the CPU, memory, and peripheral devices.

Operating System (OS)

Software that allows users to interact with computer hardware and manage resources.

Patches

Changes made to the Linux kernel that can improve performance, fix problems, or add features.

Bootloader

Software that manages the boot process of a computer.

Bootstrapping

The process of starting up a computer and creating a compiler.

Init system

A subsystem that bootstraps user space and controls daemons.

Daemons

Background services that run during boot or after logging into the desktop.

Graphical server

The subsystem that displays graphics on the monitor (X server).

Desktop Environment

The interface that users interact with on a computer.

Applications

Software programs similar to those found in an app store.

Distribution (distros)

Different versions of Linux tailored for various users (e.g., Ubuntu, Debian).

Live Distribution

A version of Linux that can run from a CD/DVD or USB without installation.

Detecting and preparing hardware

The OS identifies and loads necessary drivers for hardware components.

Managing processes

The OS tracks multiple processes and manages CPU access.

Managing memory

The OS allocates RAM and swap space to applications.

Providing user interfaces

The OS offers ways for users to access the system.

Shell

A command-line interpreter that processes user commands.

Terminal emulator

A program that allows interaction with the shell in a graphical interface.

Controlling filesystems

The OS manages file and directory ownership and access.

User access and authentication

The OS creates user accounts and sets boundaries between users.

Administrative utilities

Tools for managing users, disks, and network monitoring.

Starting up services

The OS initializes services like printers and logging.

Programming tools

Utilities for creating applications and libraries.

Clustering

Configuring multiple systems to appear as one to users.

Virtualization

Efficiently managing computing resources.

Cloud computing

Managing large-scale virtualization environments.

Real-time computing

Configuring Linux for real-time applications.

Specialized storage

Interfaces for local and networked storage.

Basic Linux Commands

Common commands used in Linux, typically in lowercase.

ls

Lists directory contents.

cd

Changes the current directory.

pwd

Displays the present working directory.

cat

Concatenates and displays files.

echo

Displays arguments to the screen.

man

Displays the online manual for commands.

exit

Exits the shell or current session.

clear

Clears the terminal screen.

touch

Creates an empty file.

id

Prints user and group IDs.

who

Shows who is logged on.

w

Displays who is logged on and their activities.

uname

Prints system information.

whoami

Prints the effective user ID.

mkdir

Creates directories.

passwd

Changes a user's password.

less

Reads a file incrementally.

head/tail

Reads the first or last 10 lines of a file.

find

Locates files on the system.

grep

Searches for a string in a file.

sort

Organizes text in a file.

wc

Counts words in a file.

vi

A text editor available in Linux.

Command Structure

The format for executing commands in Linux.

User Management

Managing user accounts and permissions in Linux.

Root account

The administrative account with UID 0.

System Accounts

Accounts created for services, not for user login.

sudo

A command that allows users to run commands as another user.

Wheel group

A group that has sudo privileges by default.

Character class

matches any of the characters included between the brackets

wildcards

a character or string used for pattern matching paths

BASH

programming language

to remove a directory in the shell

rm -r

$

standard user

#

root user

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command, options and arguments