Linux - Module 01: Introduction to Linux

Module 01Introduction to LinuxExam Objective1.1 Linux Evolution and Popular Operating SystemsObjective SummaryLearn the history of Linux and UnixUnderstand the parts of a Linux systemStart learning about Open SourceFind out where Linux runsEvolution of LinuxWhat is Linux?Linux is the kernel – the central controllerAdd some tools to get an operating systemShells (enter commands into the system)Systems management (add users)Applications (email, web, development)Package it up into a Linux distributionLinux HistoryInvented as a hobby project in 1991 by Linus Torvalds while at the University of Helsinki in FinlandPeople began contributing to make it work on their hardwareThe GNU project provided a base set of toolsWhat is UNIX?Started in the 1970’s at Bell Labs, adopted by universitiesUNIX is now a trademark of the Open GroupAn OS must be certified to be called UNIXLinux is not certified so it is UNIX-likeWhat is Linux’s job?The kernel manages application processesAllocates and reclaims memoryArbitrates access to disk and CPUAbstracts hardware specific functions so applications are hardware-agnosticProvides security and isolation of usersSwitches between multiple processes (preemptive multitasking)Open SourceHumans write software in source codeCompilers translate source to machine codeIf you have the source, you can make changes and see how it worksOpen Source means you can inspect and change the sourceLinux DistributionsKernel + tools + installation + package management = distributionRed Hat RHELFedora, CentOS, Scientific LinuxDebianUbuntu, many appliance based distributionsLinux runs onBig Iron (e.g. IBM Power Systems)Enterprise servers (Dell, HP, IBM, etc)DesktopsLaptopsSingle board (Raspberry Pi)Custom hardware (TiVo)Embedded devices/Phones (Android)Exam Objective4.1 Choosing an Operating SystemObjective SummaryUnderstanding distribution life cycle managementExamine operating system differencesDistribution Life Cycle ManagementDecision PointsWhat will the computer do?What software does it need to run?Does it need specific hardware or OS?Who has to take care of it?How long does it need to live for?Release CyclesSoftware and OS upgrades come on a release cycleUpdates can be major or minorExamplesA new version of Fedora is released every 6 monthsMinor releases of RHEL come out every 12-18moMajor releases of RHEL come out every 3-6 yearsMaintenance CyclesSoftware generally goes through phasesActively developedBugfixes onlySecurity fixes onlyNo updatesThis is the maintenance cycleA short maintenance cycle means more frequent upgrades are requiredPros and Cons of cyclesFaster releases means that newer software will be available fasterAlso means you might have to upgrade faster to stay current or will get less stable softwareLonger maintenance cycle means you will be supported at current software levels longer, needing less frequent upgradesLonger maintenance cycles often require paid support packages.Software TermsNew features are introduced in beta versionsBeta is less tested and therefore stableAfter the beta period, software is promoted to stable.If you need newer features you will often be looking at beta softwareBackward compatibility means it still works with older versionsComparing Operating SystemsWindowsSplit into desktop and server versionsSlow release cycle, long maintenance cycleEmphasis on backward compatibilityRuns a GUIImproving scripting and management abilities to compete with LinuxApple OS XRuns on Apple hardwareServer version adds packages to the desktop version to aid in management and sharingUNIX certifiedNew major releases every 18-24 months LinuxUnique in that after choosing Linux you must choose a distributionDifferent distributions focus on different use cases, e.g. desktop, server, scientific, networkSome distributions offer commercial support, most is volunteer based