Introduction to Linux - Linux Operating System - Cengage PDF

Chapter 1 Introduction to Linux Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. M ay not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. ...

Chapter 1 Introduction to Linux Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. M ay not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Objectives After completing this chapter, you will be able to: Explain the purpose of an operating system Outline the key features of the Linux operating system Describe the origins of the Linux operating systems Identify the characteristics of various Linux distributions and where to find them Explain the common uses of Linux in industry today Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Operating Systems (1 of 7) Computers have two fundamental components Hardware: physical components inside a computer Software: set of instructions or programs that allow hardware components to manipulate data Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Operating Systems (2 of 7) Hardware components Processor (CPU) Physical memory (RAM) Hard disk and solid state drives CD and DVD drives Flash memory card readers (SD cards) Sound cards Video cards Network adapter cards Ports Mainboards (motherboards) Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Operating Systems (3 of 7) Two types of programs are executed on a computer Applications (apps): programs designed for a specific use and with which a user interacts Operating system (OS) software: software components used to control the hardware of the computer Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Operating Systems (4 of 7) Device driver: software containing instructions that the OS uses to control and interact with a specific device User interface: application program that accepts user input indicating what to do, forwards this input to the OS for completion, and gives results back to the user Can be a command line prompt or a graphical user interface (GUI) Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Operating Systems (5 of 7) Figure 1-1: The role of operating system software. Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Operating Systems (6 of 7) Graphical user interface (GUI): component of an OS that the user can interact with using the keyboard or the mouse Consists of menus, dialog boxes, and symbols (known as icons) System services: applications that handle system-related tasks Printing Scheduling programs Gaining network access Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Operating Systems (7 of 7) Figure 1-2: A Linux graphical user interface. Source: Red Hat, Inc. Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  The Linux Operating System Linux: OS used to run a variety of applications on a variety of different hardware components Multiuser and multitasking OS Ability to manage thousands of tasks at the same time Allows multiple users to access the system simultaneously Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Versions of the Linux Operating System Linux kernel: core component Written almost entirely in the C programming language Software can be used to modify appearance of Linux, but the kernel is common to all Linux Important to understand Linux kernel version numbers to decide which version is appropriate Good understanding of system hardware is important in deciding which kernel version to use Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Identifying Kernel Versions Linux kernel versions components Major number: indicates major revision to Linux kernel Minor number: indicates minor revision and stability of Linux kernel Production kernel: kernel that has been thoroughly tested and is declared to be stable Developmental kernel: kernel which is not fully tested and with implied instability Revision number: most current changes to the version Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Licensing Linux (1 of 3) Open Source Software (OSS) Freely developed and continuously improved by a large community of software developers Source code List of instructions that a software developer writes to make up a program Format and structure of source code follows rules defined by the programming language in which it was written Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Licensing Linux (2 of 3) Implications of OSS software development Software is developed very rapidly through widespread collaboration Software bugs (errors) are noted and promptly fixed Software features evolve quickly based on users’ needs The perceived value of the software increases because it is based on usefulness, not on price Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Licensing Linux (3 of 3) Table 1-2 Software types Type Description Open source Software in which the source code and software can be obtained free of charge and optionally modified to suit a particular need Closed source Software in which the source code is not available; although this type of software might be distributed free of charge, it is usually quite costly and commonly referred to as commercial software Freeware Closed source software that is given out free of charge; it is sometimes referred to as freemium software Shareware Closed source software that is initially given out free of charge but that requires payment after a certain period of use Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Types of Open Source Licenses GNU Public License (GPL) Developed by the Free Software Foundation (FSF) Stipulates that the source code of any software published under its license must be freely available Users who modify the source code must also redistribute the modified code freely Artistic license: ensures source code is freely available Original author has some control over changes Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Types of Closed Source Licenses Most closed source software is sold commercially Usually bears label of manufacturer Freeware Distributed free of charge; source code is not available Shareware Initially free, but requires payment after a period of time or for use of certain features Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Linux Advantages (1 of 7) Risk reduction Changes in the market or customer needs may cause companies to change software frequently Can be costly and time-consuming Support for closed source software may end Vendor may go out of business Software version may be retired OSS products offer the opportunity to maintain and change the source code Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Linux Advantages (2 of 7) Meeting business needs Common software available for Linux Scientific and engineering software Software emulators Web servers, Web browsers, and e-commerce suites Desktop productivity software Graphics manipulation software Database software Security software Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Linux Advantages (3 of 7) Stability and security Customers using a closed source OS must rely on the vendor to fix any bugs Waiting for a hot fix may take weeks or months The collaborative open source approach to testing and fixing bugs increases the stability of Linux Bugs and security loopholes in OSS programs can be identified and fixed quickly Code is freely available and scrutinized by many developers Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Linux Advantages (4 of 7) Flexibility for different hardware platforms Partial list of hardware platforms on which Linux can run Intel x86/x64 and Itanium PA-RISC and Mainframe (S/390, z/Architecture) ARM and MIPS SPARC/Ultra-SPARC PowerPC/POWER Ease of customization Ability to control the inner workings of the OS Can choose to install only software packages needed Linux supports several programming languages, such as shell and PERL scripts to customize or automate tasks Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Linux Advantages (5 of 7) Ease of obtaining support Linux documentation found on the Internet Frequently asked questions (FAQs) HOWTO documents: maintained by authors but centrally collected by the Linux Documentation Project (LDP) Internet newsgroups Linux User Groups (LUGs): open forum of Linux users who discuss Linux-related issues and problems Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Linux Advantages (6 of 7) Cost reduction Linux is less expensive than other OSs No cost associated with acquiring the software A wealth of OSS can run on a variety of different hardware platforms running Linux Largest costs associated with Linux are costs associated with hiring people to maintain the system Total cost of ownership (TCO): overall cost of using a particular OS Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Linux Advantages (7 of 7) Table 1-3: Calculating the total cost of ownership Costs Linux Closed source operating system Operating system cost $0 Greater than $0 Cost of administration Low: Stability is high and bugs Moderate/high: Bug fixes are created by the are fixed quickly by open vendor of the operating system, which could result source developers. in costly downtime. Cost of additional software Low/none: Most software Moderate/high: Most software available for closed available for Linux is also open source operating systems is also closed source. source. Cost of software upgrades Low/none Moderate/high: Closed source software is eventually retired, and companies must buy upgrades or new products to gain functionality and stay competitive. Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  The History of Linux Figure 1-4: Timeline of UNIX and Linux development. Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  UNIX (1 of 2) Evolved from Multiplexed Information and Computing Service (MULTICS) Project was abandoned Rewritten in the C programming language Able to run on different hardware platforms AT&T sold UNIX source code to several companies Each developed its own variety, or flavor, of UNIX yet adhered to standards agreed upon by all Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  UNIX (2 of 2) Berkeley Software Distribution (BSD) Version of the original UNIX source code Common flavors of UNIX today BSD Hewlett-Packard’s HP-UX IBM’s AIX Apple’s macOS and iOS operating systems Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  The Hacker Culture (1 of 2) Hacker: a person who attempts to expand knowledge of computing through experimentation Cracker: someone who illegally uses computers for personal benefit or to cause damage Richard Stallman: famous hacker who worked at MIT Formed the Free Software Foundation (FSF) Encouraged free software development Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  The Hacker Culture (2 of 2) GNU project by Richard Stallman Promoted free development for a free OS that was not UNIX GNU project led to publication of GNU Public License (GPL) Legalized free distribution of source code and encouraged collaborative development This hacker culture of collaborative development set the stage for Linux Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Linux (1 of 2) First developed by Linus Torvalds in 1991 Published under the GNU license Linux kernel was developed collaboratively and centrally managed Hackers developed Linux add-on packages and distributions Distribution: collection of software containing Linux kernel and libraries, combined with add-on software Red Hat and OpenSUSE Debian and Ubuntu Gentoo, Linux Mint, and Arch Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Linux (2 of 2) Linux is a by-product of OSS development Changed over time Since 2000, there has been interest in embedded Linux Linux OSs that run on smaller hardware devices such as mobile devices Linux is currently very well developed More application development can be expected from the OSS community in the next decade Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Linux Distributions (1 of 5) Varied distributions of Linux are essentially the same under the surface Do have important differences Some distributions include a large number of server-related tools Web servers Database servers Most distributions include a GUI that can be further customized to suit the needs of the user Core component of this GUI is X Windows Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Linux Distributions (2 of 5) GUI environment X Windows in combination with a window manager and desktop environment Two competing GUI environments in Linux GNU Object Model Environment (GNOME) K Desktop Environment (KDE) Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Linux Distributions (3 of 5) Figure 1-5: The GNOME Desktop Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Linux Distributions (4 of 5) Figure 1-6: The KDE Desktop Source: Red hat, Inc Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Linux Distributions (5 of 5) Package manager: software system that installs and maintains software Red Hat Package Manager: most widely supported package manager Tarball: compressed archive of files containing scripts that install software to the correct location on the system Difficult to manage, upgrade, or remove from system Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Common Uses of Linux (1 of 2) Linux may be customized to provide services for a variety of companies in a variety of situations Workstation services: services used on a local computer Server services: services made available for other computers across a network Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Common Uses of Linux (2 of 2) Linux configurations commonly used today Internet servers File and print servers Application servers Cloud systems Supercomputers Scientific workstations Office/personal workstations Mobile devices Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Internet Servers Most common Internet services Web services DNS and DHCP services Time services Mail services FTP services Authentication services Certificate services Routing services Firewall and proxy services Advanced security services Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  File and Print Servers Linux is well-suited for centrally sharing resources More economical to share files and printers over a network Inherently fast and light OS A distribution specific to a certain task can be installed on the central server Can share resources with a computer running another OS Most common service used to allow clients to connect to shared information and printers on a Linux server is Samba Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Application Servers Application server: intermediary between a client computer and information, normally stored in a database Database: organized collection of data that is arranged into tables of related information Database Management Systems (DBMSs): programs designed to allow for creation, modification, manipulation, maintenance, and access of information from databases Application servers can provide management functionality Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Cloud Systems Cloud is just another term for the Internet Organizations are moving their data to servers that are hosted within data centers accessible across the Internet Cloud servers offer the advantage of accessing their data from anywhere Private cloud Cloud provider Main approaches to hosting data and services within the cloud Software as a Service (SaaS) Platform as a Service (PaaS) Infrastructure as a Service (IaaS) Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Supercomputers Clustering: combining several smaller computers to act as one large supercomputer Beowulf clustering: most common Linux method of clustering Message Passing Interface (MPI): used on Beowulf clusters to pass information to separate computers Scalability: ability for a computer to increase workload as the number of processors increases Clustering computers often results in better scalability Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Scientific/Engineering Workstation Scientific and engineering community often needs customized programs OSS programs can be used or modified to create specific scientific and engineering fields Many OSS programs are available Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Office/Personal Workstation Workstation software designed for end users in office and home environments Allow the user to create, organize, and manipulate office documents and graphic art Several OSS packages available Graphics editing software (Gimp) Desktop publishing software (Scribus) Media software (VLC) Financial software (Gnucash) Office productivity suites (Apache OpenOffice) Bittorrent clients (qBitTorrent) Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Cybersecurity Workstations Technologies and processes used to analyze existing security and provide data protections Vulnerability assessments Penetration tests Security monitoring Most tools for performing a vulnerability assessment and penetration test, as well as the tools for detecting and investigating security breaches are exclusively for Linux systems Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Mobile Devices Following Apple iPhone introduction in 2007 several Linux-based smartphone and tablets appeared Google Android in 2008 is most notable By 2017, Android was installed on over 85 percent of smartphones in the world Google Play Store hosted more than 3.5 million apps and over 85 billion downloads Other Linux distributions on mobile devices AsteroidOS, postmarketOS, and Sailfish OS SHR and Tizen Ubuntu Touch Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Summary (1 of 2) Linux is an OS whose kernel and additional software are freely developed and improved upon by a large community of software developers Linux is published under the GNU Public License. It is referred to as Open Source Software (OSS) Companies find Linux a stable, low-risk, and flexible alternative operating system Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Summary (2 of 2) Linux is available in different distributions, all having a common kernel, but packaged with different OSS applications A wide variety of documentation and resources exist: Internet Web sites, HOWTOs, FAQs, newsgroups, and LUGs Linux is an extremely versatile OS that provides a wide range of workstation and server services Eckert, Linux+ and LPIC-1 Guide to Linux Certification, 5th Edition. © 2019 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.