Linux fundamentals form the foundation for understanding how the Linux operating system works. In this guide, you will learn Linux fundamentals step by step, including basic concepts, directory structure, shells, and commonly asked Linux interview questions for beginners.
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Section 1: Linux Fundamentals
What is Linux?
Linux is an open-source, Unix-like operating system kernel. When combined with GNU tools and applications, it forms a complete Operating System used for servers, desktops, and embedded systems.
Is Linux an operating system or a kernel?
Technically, Linux is a Kernel. It is the core part that manages hardware. The complete OS you install (like Ubuntu) is a "Distribution" that includes the kernel plus software utilities.
Who created Linux?
Linux was created by Linus Torvalds in 1991. He originally developed it as a free alternative to the Minix operating system.
What is open-source software?
Open-source software is software with source code that anyone can inspect, modify, and enhance. It encourages collaboration and transparency in development.
Difference between Linux and Windows?
The main difference is that Linux is open-source, highly customizable, and uses a hierarchical file structure (root), whereas Windows is proprietary, paid, and uses drive letters (C:, D:).
Section 2: Shells & Distros
What are Linux distributions?
A distribution (distro) is an OS made from a software collection that includes the Linux kernel, a package management system, and a desktop environment.
Name some popular Linux distributions.
Commonly used distros include Ubuntu, RHEL (Red Hat), CentOS, Rocky Linux, Debian, Fedora, and Kali Linux.
What is a shell?
A shell is a command-line interpreter that acts as an interface between the user and the kernel. It takes your text commands and tells the kernel what to do.
What are different types of shells in Linux?
Popular shells include Bash (Bourne Again Shell), Zsh (Z Shell), Ksh (Korn Shell), and Fish.
What is the role of the kernel?
The kernel manages system resources. It handles communication between hardware (CPU, RAM, Disk) and software applications.
These Linux fundamentals help beginners understand how Linux manages files, processes, and system resources.
Section 3: Environment & Root
What is a terminal?
A terminal is the environment/program that allows you to interact with the shell. It provides a text-based interface to run commands.
What is CLI and GUI?
CLI: Command Line Interface (Text-based).
GUI: Graphical User Interface (Windows, Icons, Mouse-based).
GUI: Graphical User Interface (Windows, Icons, Mouse-based).
What is the root user?
The root user is the superuser in Linux who has full administrative privileges to access, modify, or delete any file on the system.
What is the Linux directory structure?
Linux uses a hierarchical tree structure starting from the root (/) directory. All files, devices, and partitions are attached as branches to this tree.
What is / (root directory)?
The / symbol represents the top-level directory. Every other directory in a Linux system is a sub-directory of the root.
You may also like our Linux Commands for Beginners.
Understanding Linux fundamentals helps beginners learn core Linux concepts, system structure, and prepares them for Linux interview questions.
Section 4: Directories
What is /home directory used for?
The /home directory stores the personal data (documents, settings, downloads) for each regular user on the system.
What is /etc directory?
The /etc directory contains all the system-wide configuration files (like network configs, user lists, and service settings).
What is /var directory?
The /var (variable) directory is where the system stores data that changes frequently, such as logs, mail, and print queues.
What is /bin and /sbin?
/bin contains essential executable commands (like `ls`, `cd`).
/sbin contains system-administration binaries used by root (like `reboot`, `iptables`).
/sbin contains system-administration binaries used by root (like `reboot`, `iptables`).
What is /tmp directory?
The /tmp directory holds temporary files created by the system and users. These files are typically cleared upon reboot.
Learn more in our Linux Interview Questions guide.
Section 5: System Management
What is a process in Linux?
A process is a program in execution. Each process is assigned a unique PID (Process ID) by the kernel to track it.
What is a daemon?
A daemon is a background process that runs continuously to handle specific system tasks (e.g., `sshd` for remote access or `httpd` for web hosting).
What is a package manager?
A package manager is a tool that allows users to install, update, and remove software easily (e.g., installing a web server with a single command).
Difference between apt, yum, and dnf?
APT: Used by Debian/Ubuntu.
YUM: Used by older RHEL/CentOS.
DNF: The modern, faster version of YUM used by Rocky Linux, Fedora, and RHEL 8+.
YUM: Used by older RHEL/CentOS.
DNF: The modern, faster version of YUM used by Rocky Linux, Fedora, and RHEL 8+.
What is a Linux service?
A service is a program that runs in the background. In modern Linux, services are managed by systemd using the command:
systemctl start [service_name]Mastering Linux fundamentals is essential for system administrators, DevOps engineers, and anyone preparing for Linux interviews.
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