Linux Essentials Chapter 1: Selecting an Operating System

Chapter 1 Outline What is an OS? Investigating user interfaces Where does Linux fit in the OS world? What is a distribution?

What Is an OS? OS kernel component Additional components

OS Kernel Components A kernel is a software responsible for: o Interfacing with hardware devices o Allocating memory to individual programs o Allocating CPU time to individual programs o Enabling programs to interact with each other Kernels are not interchangeable. Linux OS kernel: o Called Linux o Created by student Linus Torvalds in 1991 o Runs on many various platforms & hardware

What Is an OS? (continued) OS Kernel Components Additional Components Command-line shells Graphical user interfaces Utility programs Libraries Productivity programs

Investigating User Interfaces Using a Text-Mode User Interface Example: Fedora release 21 (Twenty One) Kernel fc21.x86_64 on an x86_64 (tty1) essentials login: To log in: o Enter username at login: prompt o Enter password at the password prompt After login, you receive a shell prompt: ∼ ]$

Investigating User Interfaces (continued) Using a Text-Mode User Interface Enter commands at the shell prompt: $ ls c01.doc f0101.tif $ Commands display information and immediately return a prompt or…

Investigating User Interfaces (continued) Using a Text-Mode User Interface Take over the display:

Investigating User Interfaces (continued) Using a Text-Mode User Interface Using a Graphical User Interface

Investigating User Interfaces (continued) Using a Text-Mode User Interface Using a Graphical User Interface Desktop Environment Features: o Program launchers o File managers o Window controls o Multiple desktops o Logout options

What is Open Source? Source code = Programming code human beings use to write software programs Compiler = Software that turns source code into binary code, but does not execute the binary code Translator = Software that turns source code temporarily into binary code and executes it Binary code = Code that machines need to run/understand software programs Open source = Freely available source code

Where Does Linux Fit in the OS World? Comparing Linux to Unix The Linux kernel o Based on Unix o Specifically Minix The GNU's Not Unix (GNU) project o By Free Software Foundation (FSF) o Goal: Develop open source replacements for Unix core elements Xorg-X11 o Variety of the X Windows System o X is foundation for most Unix OS GUIs

Where Does Linux Fit in the OS World? (continued) Comparing Linux to Unix The Linux kernel The GNU's Not Unix (GNU) project Xorg-X11 Desktop environments o Many open source desktop environments are on both Unix and Linux. o Examples:  GNOME  KDE  Xfce

Where Does Linux Fit in the OS World? (continued) Comparing Linux to Unix The Linux kernel The GNU's Not Unix (GNU) project Xorg-X11 Desktop environments Server programs o Both Unix and Linux are popular as Server OSs. o Examples:  Web servers  servers  File servers

Where Does Linux Fit in the OS World? (continued) Comparing Linux to Unix The Linux kernel The GNU's Not Unix (GNU) project Xorg-X11 Desktop environments Server programs User productivity programs o Linux and Unix-like OSs run similar programs. o More likely to find support on Linux

Where Does Linux Fit in the OS World? (continued) Comparing Linux to Mac OS X Mac OS X is a Unix-based OS User interface is different: o Names:  Cocoa (programming perspective)  Aqua (user perspective) o Applications developed for OS X cannot run on Linux without heavy modification. o Applications developed on Linux can run on OS X with minor (or none) modifications. OS X limited to Apple hardware Linux runs on a wide-variety of hardware.

Where Does Linux Fit in the OS World? (continued) Comparing Linux to Unix Comparing Linux to Mac OS X Comparing Linux to Windows Licensing o Linux - Open Source o Windows - Closed Source Proprietary Costs o Linux  Free licenses  Human expertise hard to find and more expensive o Windows  Costly licenses  Human expertise easy to find and less expensive

Where Does Linux Fit in the OS World? (continued) Comparing Linux to Windows Licensing Costs Hardware compatibility o Drivers  Windows - most companies provide drivers  Linux - drivers typically provided by community o Older hardware  Linux - runs better

Where Does Linux Fit in the OS World? (continued) Comparing Linux to Windows Licensing Costs Hardware compatibility Software availability o Windows - Microsoft Office reigns o Linux - Apache Web server reigns User interfaces o Windows - Proprietary o Linux - Open source & standards based

Where Does Linux Fit in the OS World? (continued) Comparing Linux to Windows Licensing Costs Hardware compatibility Software availability User interfaces Configurability o Linux is more configurable/flexible. Security o Open source software tends to be more secure. o Linux is used by the US Government.

What Is a Distribution? Creating a Complete Linux-Based OS A Linux kernel Core Unix tools Supplemental software Startup scripts An installer

A Summary of Common Linux Distributions DistributionAvailabilityPackage formatRelease cycleAdministrator skill reqs ArchFreepacmanRollingExpert CentOSFreeRPMapprox 2-yearIntermediate DebianFreeDebian2-yearIntermediate to expert FedoraFreeRPMapprox 6-monthIntermediate GentooFreeEbuildRollingExpert MintFreeDebian6-monthNovice to intermediate openSUSEFreeRPM8-monthIntermediate Red Hat Enterprise CommercialRPMapprox 2-yearIntermediate ScientificFreeRPMapprox 6-monthIntermediate to expert SlackwareFreetarballsIrregularExpert SUSE Enterprise CommercialRPM2–3 yearsIntermediate UbuntuFreeDebian6-monthNovice to intermediate

What Is a Distribution? (continued) Creating a Complete Linux-Based OS A Summary of Common Linux Distributions Specialized distributions: Android Network appliances TiVo Parted Magic

What Is a Distribution? (continued) Creating a Complete Linux-Based OS A Summary of Common Linux Distributions Understanding Release Cycles Standard release o Stable software made available on periodic basis o Support:  Given for stated amount of time  Software updates are made available for bugs and security issues.  Some distributions offer Long Term Support (LTS). o After support time has passed, best to upgrade to new release Rolling release - software is continually updated