Overview of Linux Operating System

Overview of Linux

• Definition: Linux is a family of open-source Unix-like operating systems based on the Linux kernel.
• Development: Originally created by Linus Torvalds in 1991.

Key Features

• Open Source: Source code is freely available for modification and distribution.
• Multi-user capabilities: Supports multiple users simultaneously.
• Multi-tasking: Can execute multiple processes at once.
• File System Hierarchy: Structured file system with a root directory (/).

Components of Linux

• Kernel: The core component managing hardware and system resources.
• Shell: User interface for command execution (e.g., Bash, Zsh).
• File System: Organizes data storage (e.g., ext4, XFS).
• Utilities: Programs that perform specific tasks (e.g., GNU tools).

Common Distributions

• Ubuntu: User-friendly, popular for desktops and servers.
• Fedora: Cutting-edge features, community-driven.
• CentOS: Enterprise-focused, based on Red Hat Enterprise Linux.
• Debian: Stable, versatile, with a large software repository.
• Arch Linux: Rolling release model, highly customizable.

Package Management

• Debian-based: Uses APT (Advanced Package Tool).
• Red Hat-based: Uses YUM/DNF for package management.
• Package Formats: .deb for Debian/Ubuntu and .rpm for Red Hat/CentOS.

Command Line Basics

• File Navigation: ls, cd, pwd.
• File Operations: cp (copy), mv (move), rm (remove).
• Text Viewing: cat, less, more.
• Process Management: ps, top, kill.

Permissions and Ownership

• File Permissions: Read (r), Write (w), Execute (x) for owner, group, and others.
• Commands:
  • chmod to change permissions.
  • chown to change ownership.

Networking

• Basic Commands:
  • ping to check connectivity.
  • ifconfig/ip to view network interfaces.
  • ssh for secure remote login.

System Administration

• User Management: useradd, usermod, userdel.
• Service Management: Use systemctl to manage services in systemd.
• Logs: Located in /var/log, useful for troubleshooting.

Security

• Firewalls: iptables, ufw (Uncomplicated Firewall).
• SELinux: Security-Enhanced Linux for enforcing access control policies.

Virtualization and Containers

• Virtualization: Tools like KVM, VirtualBox.
• Containers: Docker for creating and managing lightweight containers.

Community and Support

• Forums: Community support through forums and mailing lists.
• Documentation: Extensive documentation available in various forms (man pages, wikis).

Advantages of Linux

• Cost-effective: Free to use and modify.
• Security: Less susceptible to malware.
• Stability: High uptime and performance.
• Customization: Highly configurable to suit user needs.

Overview of Linux

• Linux is an open-source family of operating systems built on the Unix-like Linux kernel, introduced by Linus Torvalds in 1991.

Key Features

• The source code is available for free, allowing modification and distribution by anyone.
• Supports multi-user functionality, enabling simultaneous use by multiple users.
• Employs multi-tasking, allowing many processes to run concurrently.
• Organized file system with a root directory (/) to manage data efficiently.

Components of Linux

• The kernel serves as the core, managing hardware interactions and system resources.
• The shell is the command-line interface for executing user commands, with popular versions like Bash and Zsh.
• The file system structures data storage, with common types being ext4 and XFS.
• Utilities include specific programs for tasks, such as GNU tools.

Common Distributions

• Ubuntu is widely used for desktops and servers due to its user-friendly nature.
• Fedora is known for featuring the latest innovations and operates under community involvement.
• CentOS is tailored for enterprises, maintaining compatibility with Red Hat Enterprise Linux.
• Debian is recognized for its stability and rich software repository.
• Arch Linux uses a rolling release approach, focusing on customization.

Package Management

• Debian-based systems utilize APT (Advanced Package Tool) for handling packages.
• Red Hat-based systems implement YUM/DNF for package management tasks.
• Different package formats include .deb for Debian/Ubuntu and .rpm for Red Hat/CentOS.

Command Line Basics

• File navigation commands include ls for listing files, cd for changing directories, and pwd for displaying the current directory.
• Common file operations are cp for copying files, mv for moving them, and rm for removing files.
• Text viewing can be done using cat, less, or more.
• Process management commands include ps to display running processes, top for real-time system monitoring, and kill to stop processes.

Permissions and Ownership

• Linux implements a permissions system with Read (r), Write (w), and Execute (x) attributes assigned to the owner, group, and others.
• The chmod command allows users to modify file permissions, while chown changes file ownership.

Networking

• Basic network commands include ping for checking connectivity, and ifconfig or ip for displaying network interfaces.
• ssh enables secure remote access to other systems.

System Administration

• User management is conducted using commands like useradd, usermod, and userdel.
• Service management on systems utilizing systemd is performed with systemctl.
• System logs are stored in /var/log, providing critical data for troubleshooting.

Security

• Firewalls for Linux networks can be managed with iptables and ufw (Uncomplicated Firewall).
• SELinux (Security-Enhanced Linux) ensures strict access control policies for enhanced security.

Virtualization and Containers

• Virtualization capabilities are provided by tools such as KVM and VirtualBox for running virtual machines.
• Docker is a prominent tool for creating and managing lightweight application containers.

Community and Support

• User communities offer support through forums and mailing lists, enriching the Linux ecosystem.
• Extensive documentation is available in forms like man pages and wikis to assist users.

Advantages of Linux

• Linux is cost-effective as it is free to use and modify.
• It demonstrates robust security, being less vulnerable to malware attacks.
• High stability is evident with impressive uptime and performance levels.
• Customizability allows users to tailor their systems according to their preferences and requirements.

Explore the fundamentals of the Linux operating system, including its open-source nature, multi-user capabilities, and file system hierarchy. Learn about the key components such as the kernel, shell, and various distributions like Ubuntu and Fedora.