computer science

Linux

Linux is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Linux rather than just read about it. In short: Linux ( LIN-uuks) is a family of free and open-source software Unix-like operating systems based on the Linux kernel, which was first released on 17 September 1991 by Linus Torvalds. Some members of the family are typically packaged as a distribution (a.k.a. distro), which includes the kernel alongside supporting system software and libraries developed by third parties—such as GNU, Red Hat, and X.Org—to create a com…

Key takeaways

Linux belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Linux to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Linux from memory before moving on to harder problems.

Reference excerpt

Linux ( LIN-uuks) is a family of free and open-source software Unix-like operating systems based on the Linux kernel, which was first released on 17 September 1991 by Linus Torvalds. Some members of the family are typically packaged as a distribution (a.k.a. distro), which includes the kernel alongside supporting system software and libraries developed by third parties—such as GNU, Red Hat, and X.Org—to create a complete operating system; however, not all Linux-based operating systems are considered distros, with Android being an example. Linux was originally designed as a clone of Unix and is distributed under the copyleft GPL license. There are many thousands of Linux distributions, many based directly or indirectly on other distributions; popular Linux distros include Debian, Fedora Linux, Linux Mint, Arch Linux, and Ubuntu, while commercial distributions include Red Hat Enterprise Linux, SUSE Linux Enterprise, and ChromeOS. Linux distributions are frequently used in server platforms. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses and recommends the name "GNU/Linux", to emphasize the use and importance of GNU software in many distributions. There is controversy surrounding this. Other than the Linux kernel, key components that make up a distribution may include a display server (windowing system), a package manager, a bootloader, and a Unix shell.

Linux is one of the most prominent examples of free and open-source software collaboration. The Linux kernel is considered by many to be the largest free and open source project. While originally developed for x86-based personal computers, it has since been ported to more platforms than any other operating system. When combined with Android, which uses a Linux-based kernel and is designed for smartphones, they have the largest installed base of all general-purpose operating systems.

Overview The Linux kernel was created by Linus Torvalds, following the lack of a working kernel for GNU, a Unix-compatible operating system made entirely of free software that had been in development since 1983 by the GNU Project, led by Richard Stallman. A working Unix system called Minix was later released but its license was not entirely free at the time and it was made for education purposes. The first entirely free Unix for personal computers, 386BSD, did not appear until 1992, by which time Torvalds had already built and publicly released the first version of the Linux kernel on the Internet. Like GNU and 386BSD, Linux did not have any Unix code, being a fresh re-implementation, and therefore avoided legal issues from AT&T. Linux distributions became popular in the 1990s and made Unix technologies accessible to home users on personal computers whereas previously it had been confined to sophisticated workstations. Desktop Linux distributions include a windowing system such as X11 or Wayland and a desktop environment such as KDE Plasma, GNOME, or Xfce. Distributions intended for servers may not have a graphical user interface at all or include a solution stack such as LAMP. The source code of Linux may be used, modified, and distributed commercially or non-commercially by anyone under the terms of its respective licenses, such as the GNU General Public License (GPL). The license means creating novel distributions is permitted by anyone and is easier than it would be for an operating system such as macOS or Microsoft Windows. The Linux kernel, for example, is licensed under the GPLv2, with an exception for system calls that allows code that calls the kernel via system calls not to be licensed under the GPL. Because of the dominance of Linux-based Android on smartphones, Linux, including Android, has the largest installed base of all general-purpose operating systems as of May 2022. Linux is, as of March 2024, used by around 4 percent of desktop computers. The Chromebook, which runs the Linux kernel-based ChromeOS, dominates the US K–12 education market and represents nearly 20 percent of sub-$300 laptop sales in the US. Linux is the leading operating system on servers (over 96.4% of the top one million web servers' operating systems are Linux), leads other big iron systems such as mainframe computers, and is used on all of the world's 500 fastest supercomputers (as of November 2017, having gradually displaced all competitors). Linux also runs on embedded systems, i.e., devices whose operating system is typically built into the firmware and is highly tailored to the system. This includes routers, automation controls, smart home devices, video game consoles, televisions (Samsung and LG smart TVs), automobiles (Tesla, Audi, Mercedes-Benz, Hyundai, and Toyota), and spacecraft (Falcon 9 rocket, Dragon crew capsule, and the Ingenuity Mars helicopter).

History

Precursors

… excerpt ends here. Continue reading the full article.

Illustrations

Linux: Linus Torvalds, principal author of the Linux kernel — Linus Torvalds, principal author of the Linux kernel

Tux is sometimes stylized with incorporation of the GNU logo

Worked examples

Example 1 — a first encounter with Linux

Start with the simplest possible case. Write down what Linux claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Linux before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Linux ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Linux

In research: Linux appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Linux in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Linux is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1991 software, Computing platforms, Cross-platform software, so understanding it makes those chapters shorter.
In everyday life: Look for Linux outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Linux in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Linux means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Linux out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Linux in simple terms?

Why does Linux matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Linux?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Linux.