Day 02: Linux- A Compact Overview

LINUX

Linux is a free open-source, Unix-like operating system known for its stability, security, and versatility. It's at the heart of various Linux distributions used in servers, desktops, and embedded systems. It is developed by Linus Torvalds.

Features of Linux

Open Source: Linux is open-source software, with freely accessible source code.
Multi-User Support: It allows multiple users to work on the same system simultaneously.
Multi-Tasking: Linux handles multiple processes and tasks concurrently.
Stability: Linux is highly stable, with fewer system crashes.
Security: It features robust security controls and is less vulnerable to malware.
Scalability: Linux runs on a wide range of hardware, from small embedded devices to supercomputers.
Customization: Users can tailor Linux distributions to their specific needs.
Large Software Ecosystem: A vast repository of open-source software is available.
Command-Line Interface: Linux offers a powerful command-line interface.
Compatibility: It can run various file formats and software.
Fast Updates: Regular updates and security patches are released.

Some Flavors of LINUX

RHEL

Ubuntu

Debian

Amazon Linux

CentOS

Linux Architecture

The architecture of a Linux System consists of the following layers:

Hardware layer − Hardware consists of all peripheral devices (RAM/ HDD/ CPU etc).
Kernel − It is the core component of the Operating System, and interacts directly with hardware.
Shell − An interface to the kernel, from users. The shell takes commands from the user and executes the kernel's functions.
Application/Utilities − Utility programs that provide the user with most of the functionalities of an operating system.

Linux Folder Structure

Basic Linux Commands

Command	Syntax	Example	Description
ls	ls [options] [directory]	ls -l /home/user	List files and directories in a directory.
cd	cd [directory]	cd /var/www	Change the current directory.
pwd	pwd	pwd	Print the current working directory.
touch	touch [filename]	touch file.txt	Create an empty file.
mkdir	mkdir [directory]	mkdir new_directory	Create a new directory.
rm	rm [options] [file/directory]	rm file.txt	Remove files or directories.
cp	cp [options] source destination	cp file.txt /backup	Copy files or directories.
mv	mv [options] source destination	mv file.txt new_location	Move or rename files or directories.
cat	cat [file]	cat textfile.txt	Display the contents of a file.
more	more [file]	more longfile.txt	View file contents page by page.
man	man [command]	man ls	Access manual pages and documentation.
uname	uname [options]	uname -a	Display system information such as the kernel name, network node hostname, kernel release, kernel version, machine hardware name, and processor type.
lsb_release -a	lsb_release [options] -a	lsb_release -a	Show Linux Standard Base (LSB) and distribution-specific information about the operating system.
echo	echo [options] [string]	echo "Hello, World!"	Print the specified string to the terminal.
cat	cat [options] [file]	cat file.txt	Display the contents of one or more files.
useradd -m	useradd [options] -m username	useradd -m john	Create a new user account and create a home directory for the user.
su	su [options] [username]	su root	Switch user to another account (usually to the root user).
rm	rm [options] [file/directory]	rm file.txt	Remove files or directories.
rm -rf	rm [options] -rf [directory]	rm -rf /path/to/directory	Remove directories and their contents forcefully.
cd ..	cd ..	cd ..	Move up one level in the directory structure to the parent directory.
cd ~	cd ~	cd ~	Change the current working directory to the user's home directory.
cd /	cd /	cd /	Change the current working directory to the root directory of the file system.