Getting Started With Linux

Source: Dev.to

Base Knowledge

GNU – a predecessor of Linux and a free, open‑source Unix‑like operating system.

Kernel – the core of an operating system; it bridges software and hardware, managing resources such as CPU, memory, and peripheral devices. Although the term “Linux” is often used to refer to the whole operating system, it technically denotes only the kernel.

What Is Linux?

Linux is an open‑source operating system kernel originally created by Linus Torvalds. In everyday usage, “Linux” usually means a complete operating system built from the Linux kernel together with tools, libraries, and software from the GNU project.

Linux System Architecture

A Linux system is divided into three layers:

1. Hardware – physical resources (CPU, memory, devices, etc.).
2. Linux Kernel – core component that manages hardware and enables communication between software and hardware.
3. User Space – environment where users interact with the system via applications and command‑line interfaces.

Linux Distributions

A distribution (distro) bundles the Linux kernel with specific software, tools, utilities, libraries, and applications, providing a ready‑to‑use operating system.

Debian

Debian is an operating system composed entirely of free and open‑source software. It is highly respected in the community.

Package Management
Debian uses the powerful apt (Advanced Package Tool) system and maintains a massive repository of pre‑compiled packages.

Red Hat Enterprise Linux (RHEL)

RHEL is a commercial distribution developed by Red Hat, designed for long‑term stability, security, and professional support.

Package Management
RHEL uses the RPM (Red Hat Package Manager) format. Package management tools include YUM (Yellowdog Updater, Modified) and its successor DNF (Dandified YUM).

Ubuntu

Ubuntu is a popular, beginner‑friendly distribution based on Debian.

Package Management
Ubuntu inherits Debian’s package management, using the apt command‑line utility for installing, updating, and removing software.

Fedora

Fedora is a community‑driven distribution sponsored by Red Hat, built on the same foundations as RHEL.

Package Management
Fedora uses the RPM format and manages software with DNF, a powerful and easy‑to‑use command‑line tool.

The Shell

A shell is a program that accepts typed commands and passes them to the operating system. Graphical terminals such as “Terminal” or “Console” simply open a shell session.

Bash (Bourne Again Shell)

Bash is the default shell for most Linux distributions. Other shells (e.g., ksh, zsh, tsch) exist, but mastering Bash provides a solid foundation.

When you open a terminal, you’ll see a prompt that typically looks like:

username@hostname:current_directory$

The $ indicates the shell is ready for commands; you do not type the $ itself.

Example

echo "I love Linux"

Output:

I love Linux

Filesystem Basics

Linux uses a single root filesystem, meaning everything starts from /. There are no drive letters (e.g., C:); all storage devices are mounted into the same directory tree.

Common Directories

• / – root of the filesystem
• /home – user home directories
• /etc – system configuration files
• /var – variable data (logs, cache, spool)
• /usr – user‑installed software and libraries
• /bin and /sbin – essential system binaries

In Linux, everything is treated as a file, including devices, processes, and sockets.

Paths

• Absolute path – starts from / (e.g., /home/user/projects).
• Relative path – relative to the current directory (e.g., projects/my-app).

Useful Navigation Commands

pwd   # show current directory
ls    # list files
cd    # change directory

Permissions & Users

Linux is a multi‑user operating system with security built in. Every file and directory has an owner, a group, and a set of permissions.

You can view permissions with ls -l:

• Root – the superuser with full access.
• Normal users – have limited permissions; they can execute privileged commands using sudo.

Permissions are a core concept in Linux and a primary reason servers are secure by default.

Networking Basics

Linux provides powerful built‑in tools for inspecting, debugging, and interacting with networks—essential skills for servers, containers, and cloud environments.

Network Concepts

• IP address – identifies a machine on a network.
• Ports – identify services running on a machine.
• Protocols – rules for communication (e.g., HTTP, TCP, UDP).

Common Networking Commands

ping "url.com"

curl "url.com"