What is Linux?

Originally developed in 1990 as a PhD thesis by Linus Torvalds as a UNIX “variant” to run on Personal Computers. Linux has been generally available since the mid ‘90s, and has reached a user-base that spans industries and continents. Linux is everywhere - . in your phones, in your cars, in your refrigerators, your Roku devices. It runs most of the Internet websites, supercomputers making scientific breakthroughs, and the world's stock exchanges, desktops, servers, and embedded systems Like Windows XP, Windows 7, Windows 8, and Mac OS X, Linux is an operating system - software that manages all of the hardware resources associated with your server,desktop or laptop. The OS is comprised of a number of pieces:

 The Bootloader: The software that manages the boot process of your computer. For most users, this will simply be a splash screen that pops up and eventually goes away to boot into the operating system.

 The kernel: This is the one piece of the whole that is actually called “Linux”. The kernel is the core of the system and manages the CPU, memory, and peripheral devices. The kernel is the “lowest” level of the OS.

 Daemons: These are background services (printing, sound, scheduling, etc) that either start up during boot, or after you log into the desktop.

 The Shell: You’ve probably heard mention of the Linux command line. This is the shell – a command process that allows you to control the computer via commands typed into a text interface. This is what, at one time, scared people away from Linux the most (assuming they had to learn a seemingly archaic command line structure to make Linux work). This is no longer the case. With modern desktop Linux, there is no need to ever touch the command line.

 Graphical Server: This is the sub-system that displays the graphics on your monitor. It is commonly referred to as the X server or just “X”.

 Desktop Environment: This is the piece of the puzzle that the users actually interact with. There are many desktop environments to choose from (Unity, GNOME, Cinnamon, Enlightenment, KDE, XFCE, etc). Each desktop environment includes built-in applications (such as file managers, configuration tools, web browsers, games, etc).  Applications: Desktop environments do not offer the full array of apps. Just like Windows and Mac, Linux offers thousands upon thousands of high-quality software titles that can be easily found and installed. Most modern Linux distributions (more on this in a moment) include App Store-like tools that centralize and simplify application installation. For example: Ubuntu Linux has the Ubuntu Software Center (Figure 1) which allows you to quickly search among the thousands of apps and install them from one centralized location.

It’s free, under GNU Public License (GPL). Although there are current controversies regarding LINUX and GNU. See https://en.wikipedia.org/wiki/GNU for details. Of course these are limited to the conventions of the General Use Public License (GPL). The main drawback to LINUX is “open source”. In simple terms, usage and support. As an open source OS; the onus is on the user to keep up with the latest devlopments. Also the user interface is NOT Windows. You have to get used different desktops as opposed to Windows (expeptinf 8.1 and 10). And support for OS maintenance is not simple; though it is much better than it used to be. Much software is OS release dependent.

What is a LINUX “distribution?" Linux has a number of different versions to suit nearly any type of user – a distribution or “distro” available as a free .iso bootable image from the Internet Each “flavor” of Linux to match your needs. These versions are called distributions (or, in the short form, “distros.”). Nearly every distribution of Linux can be downloaded for free, burned onto disk (or USB thumb drive), and installed (on as many machines as you like). The most popular workstation distributions are:

 Ubuntu

 Debian

 Knoppix

 RedHat

 Fedora

 Centos  openSUSE.

Each distribution has a different take on the desktop, server or “live” distribution. There are a variety of modern user interfaces (such as Ubuntu’s Unity, KDE or GNOME. You can check out the top 100 distributions on the Distrowatch site.

The most popular server distributions are:

 Red Hat Enterprise Linux

 Ubuntu Server (LTS)

 CentOS

 SUSE Enterprise Linux.

Some of the above server distributions are free (such as Ubuntu Server and CentOS) and some have an associated price (such as Red Hat Enterprise Linux and SUSE Enterprise Linux). Those with an associated price also include support. Which distribution you use will depend on your skill level, desktop interface and usage. The distro you use can take one of three forms: Server, desktop or “live” distribution. For a beginner Ubuntu workstation or a “live” CD version is best until you become familiar with basic system administration

For new users, check out “The Best Linux Distribution for New Users”, to make the selection a much easier task.

Which is a “port”? LINUX is not just used in native mode, It has other implementations - with locked down user interfaces (UI) such as Android, With embedded systems just as phones, ATMs, POS systems. These implementatios are usually application specific “ports” with an underlying LINUX OS kernel as the underlying OS. See also Mac OSx (FREEBSD port).

Installing Linux and software

Linux offers one of the easiest installations of all operating systems. In fact, most versions of Linux offer what is called a Live distribution – which means you run the operating system from either a CD/DVD or USB flash drive without making any changes to your hard drive. You get the full functionality without having to commit to the installation. Once you’ve tried it out, and decided you wanted to use it, you simply double-click the “Install” icon and walk through the simple installation wizard. In this situation this usually wipes out the entire contents of the drive. For other installation type (VM, dual boot), consider taking an administration class such as CIS 228

Command line is the most flexible method of maintaining LINUX systems. However the GUI interface of the LINUX desktops has improved dramatically of the the past decade. For a more in-depth guide to installing Linux, take a look at “How to Install and Try Linux the Absolutely Easiest and Safest Way”, or download the Linux Foundation\'s PDF guide for Linux installation.

More Resources If you’re looking for one of the most reliable, secure, and dependable platforms for both the desktop and the server, look no further than one of the many Linux distributions. With Linux you can assure your desktops will be free of trouble, your servers up, and your support requests at a minimum. If you’re looking for more resources to help guide you through your lifetime with Linux, check out the following resources:

 Linux.com: Everything you need to know about Linux (news, how-tos, answers, forums, and more )

 Linux.org: Everything about the Linux kernel (with plenty of beginner, intermediate, and adavanced tutorials)

 Howtoforge: Linux tutorials

 Linux Documentation Project: Plenty of documentation (some may be out of date)

 Linux Knowledge Base and Tutorial: Plenty of tutorials.