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Operating System (OS)

Provides all the fundamental features of a computer from a software perspective. It enables the use of hardware devices, defines user interface standards, and provides basic tools for applications to run.

Kernel

A software component responsible for managing various low-level features of the computer. The kernel is the software “glue” that holds the computer together.

Primary Kernel Functions

Interfacing with hardware devices (network adapters, hard disks, etc.); Allocating memory to individual programs; Allocating CPU time to individual programs; Enabling programs to interact with one another.

Linux

Technically refers only to the kernel. It was created by Linus Torvalds in 1991.

Unix

The OS that Linux is modeled after. It was created in 1969 at AT&T’s Bell Labs.

The GNU Project

An effort by the Free Software Foundation (FSF) to develop open source replacements for all the core elements of a Unix OS. GNU is an example of a recursive acronym (GNU’s Not Unix).

BSD

Apple macOS, a commercial Unix-based OS, borrows heavily from the BSDs. Open source tools were developed for the BSD Unix variants as an alternative to GNU tools.

(Unix Variants)

Open Source Software

Software that you can not only run, but also modify and redistribute yourself.

Binary Code

The form a program must take for a computer to run it. Programmers create binaries—program files for a particular processor and kernel—for each OS.

Shell

A program in which users interact with computers by typing commands (text-mode).

BASH

The Bourne Again Shell (Bash) is popular in Linux.

popular linux shell

$

In command examples, the ordinary user prompt is typically represented by 

#

The administrative user (root user account) prompt is typically represented by

Graphical User Interface (GUI)

Relies on icons, menus, and a mouse pointer rather than typed commands.

X Window System (X)

The basic GUI relied upon by Linux.

Linux Desktop Environments

Program suites that provide a more complete user experience atop the X Window System. Common examples are GNOME (GNU Object Model Environment), KDE (K Desktop Environment), Cinnamon, and Xfce.

Terminal

A window inside common Linux GUIs that provides a shell prompt and the means to run text-mode programs.

ls

Short for "list," used to see a list of files in the current directory.

Linux Distribution

A bundle of components required to run a Linux system. It consists of a Linux kernel along with a set of utilities and configuration files, resulting in a complete OS.

Core Unix Tools

Tools critical to the normal functioning of a Linux system, such as the GNU tool set, the X Window System, and disk management utilities.

Distribution component

Packages

Collections of many files in one. They maintain a local database of installed files, simplifying upgrades and uninstallations.

RPM

The RPM Package Manager system. Used by CentOS, Fedora, openSUSE, and Red Hat Enterprise.

Debian Package Format

Used by Debian, Mint, and Ubuntu.

Rolling Release

Distributions (like Arch and Gentoo) that have no version numbers in the usual sense; upgrades occur in an ongoing manner, eliminating the need for a full system upgrade.

beginner friendly

Fedora, Ubuntu, and Mint. They handle most software/hardware configuration issues and provide user-friendly graphical tools.

Alpha Software

Extremely new pre-release software that is very likely to contain serious bugs.

Embedded Systems

Describes running a small, stripped-down Linux system on a small microcomputer, such as a phone or monitoring device.

Android (cell phones/tablets), TiVo (DVR), Network Appliances (broadband routers), and IoT Devices (Raspberry Pi, Beagle Bones).

IaaS (Infrastructure as a Service)

Cloud model where the vendor provides low-level server resources (CPU, memory, storage); the customer supplies the operating system and applications.

PaaS (Platform as a Service)

Cloud model where the vendor provides the physical environment as well as the operating system environment; the customer focuses mainly on developing the applications.

SaaS (Software as a Service)

Cloud model where the vendor provides a complete application environment (physical server, OS, and application software), such as a mail server or web server.

copyright

legally recognized right to create a copy of something. I

license

legal document that claims to modify the rights granted by copyright law.

General Public License (GPL)

license used by the Linux kernel, grants you the right to redistribute the software, including both the source code and binaries.

site license

a license for a proprietary program that grants an organization the right to make a certain number of copies of the program—say, 100 copies of a word processor for all of the company’s computers

Free Software Foundation (FSF)

driving force behind the GNU’s Not Unix (GNU) project

1985 by Richard Stallman

software freedoms

Freedom to use the software for any purpose ■

Freedom to examine the source code and modify it as you see fit

Freedom to redistribute the software 

Freedom to redistribute your modified software

freeware

generally refers to software that’s free of charge but not necessarily free as in speech.

copyleft

require that any modified programs derived can be distributed only under the same license terms of the original program.

sometimes called reciprocal licensing .

GPLv3

contains clauses to combat use of hardware restrictions that limit the FSF’s four freedoms and to address issues related to software patents.

Lesser GPL (LGPL)

used for libraries, which are collections of code that can be used by other programs.

GNU Free Documentation License (FDL)

for use in documentation rather than by programs. The GPL, being written for software, doesn’t apply perfectly to static documents, so the FSF created this.

ex: wikipedia

Open source initiative (OSI)

an umbrella organization for open source software in general.

promote open source software in the business world.

open source principles

free redistribution

source code availability

permission to derive work

respect for source code integrity

no discrimination

auto license distribution

lac of product specificity 

lack of restrictions on other software

technology neutrality 

Creative Commons

licenses are aimed at audio recordings, video recordings, textual works, and so on, not just computer programs

licenses that help creators retain their works’ copyrights but at the same time allow others to freely copy, distribute, and use the original artist’s work in a noncommercial manner

Berkeley Source Defi nition ( BSD)

licenses are used by the open source BSD OSs and by various software components developed for them

allow modifications to be distributed under other licenses.

MIT

open source license 

originally used for x and continues to be used for xorg-x11 and now weyland

apache

an open source license that permits redistribution under the same or another license. If a text fi le called NOTICE comes with the original work, it must be included in any derived work. This enables the original developer to provide contact or other information, even to users of heavily modifi ed versions of the program.

service and support

The product itself can be open source, and even given away for free, while the company sells services and support, such as training and a technical support phone line. For instance, a game might be open source but require a subscription to an online service to provide a full set of features.

Dual Licensing

A company can create two versions of the product: one version is completely open source, and another adds features that are not available in the open source version

multiple products

The open source product may be just one offering from the company, with revenue being generated by other product lines. These other product lines could be other software or some other product, such as manuals

open source drivers

They might opt to release drivers, or perhaps even hardware-specifi c applications, as open source as a way to promote their hardware.