LINUX BASICS (BASIC - INTERMEDIATE LEVEL)

🐧 What is Linux?

Linux is a free and open-source operating system used in computers, servers, mobile phones (like Android), and many smart devices. It's fast, secure, and highly customizable.

🧠 Core Components of Linux

• 🔧 Kernel – The heart of the OS that talks to hardware.
• 🖥️ Shell – The interface where users type commands.
• 🗂️ File System – Organizes files and folders in a tree structure.
• 🛠️ Utilities & Tools – Programs that help manage and operate the system.

🗃️ Linux File Structure (FHS - Filesystem Hierarchy Standard)

• / – The root directory, base of the Linux system.
• /home – Personal space for each user.
• /etc – System and configuration files.
• /bin – Essential system programs.
• /var – Logs and temporary system data.
• /dev – Represents hardware devices.
• /tmp – Temporary files used during processing.
• /boot – Files needed to start the system.

👤 Users and Permissions

• 👑 Root user – The superuser with full control.
• 👨‍💻 Regular users – Limited access for safety.
• 🔐 Permissions – Control who can read, write, or run files.
• 🧑‍🤝‍🧑 Groups – Users can belong to groups to manage access easily.

📦 Package Management

Linux software is usually managed via package managers. They help you to install, update, or remove applications easily.

• Debian-based (like Ubuntu): Uses .deb packages.
• RedHat-based (like CentOS): Uses .rpm packages.

🔄 Processes and Services

• 🧩 Everything running is called a process.
• 🧠 Some processes keep running in the background as services (e.g., network, Bluetooth).
• ⚙️ You can start, stop, or monitor these services as needed.

🌐 Why Use Linux?

• ✅ Stable and rarely crashes.
• 🔓 Open-source – You can see and modify the code.
• 🔐 Secure – Fewer viruses and threats.
• 💻 Lightweight – Runs even on older hardware.
• 🧪 Developer-friendly – Preferred by programmers, sysadmins, and DevOps.