Introduction to Linux
Linux is a free, open-source OS kernel created by Linus Torvalds in 1991. Combined with GNU tools, it forms complete operating systems powering servers, desktops, mobile (Android), and supercomputers.
History
Inspired by MINIX and Unix. Released 1991 under GPL. GNU project (Stallman, 1983) provided essential tools. GNU/Linux became a viable free alternative. Today dominates servers, cloud, and mobile.
Open Source
Source code freely available to view, modify, distribute. GPL requires derivatives to remain open. Enables collaboration, transparency, security through audit, avoids vendor lock-in.
Distributions
Ubuntu (user-friendly), CentOS/Rocky/Alma (enterprise, RHEL-based), Fedora (cutting-edge), Debian (stability), Arch (rolling release), Kali (security testing). Differ in package managers, release cycles, targets.
Architecture
Kernel (hardware management, process scheduling, memory, drivers), shell (bash, zsh), system libraries (glibc), system utilities (coreutils), applications. Kernel manages hardware; everything else in user space.
Linux in Industry
96% of top web servers, most cloud infrastructure, Android phones, IoT, 100% of Top500 supercomputers. Essential skills for sysadmins, DevOps, cloud architects, security professionals.
Summary
Linux is the dominant OS for servers and cloud. Understanding its history, open-source philosophy, distributions, and architecture is foundational.