Linux

Origins & Founders

• Created in 1991 by Linus Torvalds, a Finnish computer science student.
• Initially developed as a personal project to build a free Unix‑like operating system kernel.
• Released under the GNU General Public License (GPL), allowing anyone to use, modify, and distribute it.
• Combined with GNU tools (from Richard Stallman’s Free Software Foundation), it became a full operating system.

Historical Evolution

• 1991: First Linux kernel released (version 0.01).
• 1990s: Rapid growth through community contributions; distributions like Slackware, Debian, and Red Hat emerged.
• 2000s: Linux gained traction in servers, supercomputers, and embedded systems.
• 2010s–2020s: Became dominant in cloud computing, Android smartphones (built on Linux kernel), and IoT devices.

Architecture

• Kernel:
  • Monolithic kernel — manages processes, memory, device drivers, networking, and file systems.
  • Modular design allows loading/unloading of drivers at runtime.
• User Space:
  • GNU utilities (bash shell, coreutils).
  • Libraries (glibc) provide APIs for applications.
• File System:
  • Ext4 is the most common, but supports many (XFS, Btrfs, ZFS).
• Security: User/group permissions, SELinux/AppArmor for mandatory access control.

Key Features

• Open Source: Free to use, modify, and distribute.
• Distributions (Distros): Ubuntu, Fedora, Debian, Arch, CentOS, etc.
• Portability: Runs on servers, desktops, mobile devices, embedded systems.
• Stability & Performance: Powers most of the world’s servers and supercomputers.
• Community Driven: Thousands of contributors worldwide.

Usage Scenarios

• Servers & Cloud: Web servers, databases, cloud infrastructure.
• Desktop Computing: Ubuntu, Fedora, Mint for everyday use.
• Mobile: Android smartphones run on the Linux kernel.
• Embedded Systems: Routers, smart TVs, IoT devices.
• Supercomputers: Over 90% of the world’s fastest supercomputers run Linux.