ìComputer Systems and NetworksECPE170– JeffShafer– UniversityofthePacific

LinuxBasics

Pre-Lab

ì EveryoneinstalledLinuxontheircomputer

ì Everyonelaunchedthecommandline(“terminal”)andranafewcommands

ì Whatproblemswereencountered?ì Virtualizationsupportinprocessornotenabled(BIOS)ì VMWare Player(currentversion)onlyrunsonWindows64ì 3Dgraphicsvirtualizationincompatiblewithspecifichardwareì Oldvirtualmachinesoftwareì Others?

ì Tip:IfyouhaveproblemsmaximizingyourVMtofullscreen,ordoingcopy-and-pastebetweenLinuxandWindows,makesureyouinstalledtheVMtools

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Person of the Day: Linus Torvalds

ì Creatorof LinuxKernelì Startedin1991ì Firstdeveloper– hobby

project(forfun!)ì Modernkernelisproductof

workbythousandsofprogrammers

ì Currently“finalauthority”onwhatisincludedinthekernel

ì CreatorofGit versioncontrolsystemì InitiallyforLinuxkerneldev

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Operating System Tasks

ì WhatdoestheOSneedtodo?ì Scheduleprocessestorunì Memorymanagementì Interrupthandling(managehardwareingeneral)ì Security(betweenprocesses)ì Networkaccessì Storagemanagement(filesystem)ì Graphicaluserinterface

ì MaybeamiddlewarelayerontopoftheOS

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Operating Systems – Processes

ì Processmanagementisakeyoperatingsystemtask

ì OSmustinitiallycreateprocesses whenyourunyourprogram

ì OScanallowprocessestoaccessresourcesì Mustschedule accesstoshared resources(e.g.,CPU)

ì OScanallowprocessestocommunicate witheachother

ì OSmustcleanupafterprocessfinishesì Deallocate resources(e.g.memory,networksockets,file

descriptors,etc…)thatwerecreatedduringprocessexecution

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Operating Systems – Scheduling

ì Theoperatingsystemschedulesprocessexecutionì Whatprocessesareallowedtorunatall?ì Whatprocessesareallowedtorunrightnow?

ì ContextswitchesoccurwhentheCPUistakenfromoneprocessandgiventoanotherprocessì CPUstate(registers,currentPC,etc…)ispreserved

duringacontextswitch

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Operating Systems – Scheduling

ì PreemptiveSchedulingì Eachprocessisallocatedatimeslice.ì Whenthetimeslice expires,acontextswitchoccurs

ì Acontextswitchcanalsooccurwhenahigher-priorityprocessneedstheCPU

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Operating Systems – Security

ì ProcessAisforbiddenfromreading/modifying/writingthememoryofProcessBì Virtualmemory isahugehelphere!ì Eachprocesshasaseparatevirtual addressspacethat

mapstodifferentregionsofphysicalmemory

ì ProcessAhasotherlimitsbesideswhichmemorypagesitcanaccessì Whataresomeotherlimits?ì Amountofmemoryconsumedì Numberofopenfilesondiskì Whichfilesondiskcanberead/written

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Operating Systems – Filesystem

ì OSisresponsibleformanagingdataonpersistentstorage

ì Jobofthefilesystem!ì Whatfilesexist?(i.e.names)ì Howaretheyorganized?(i.e.paths/folders)ì Whoownsandcanaccessthem?(i.e.usernames,

permissions)ì Whereareindividualfileblocksstoredonthedisk?

ì i.e.filename“database.dat”isreallycomposedof15823blocks,ofwhichblock1islocatedatlogicalblockaddress#...ontheharddrive.

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Operating Systems – Device Management

ì Managedevicesì HowdowesenddatatotheNICfortransmission?ì Howdowerenderanimagefordisplayonscreen?ì HowdowereadablockofdatafromourRAIDdisk

controller?

ì Operatingsystemscanbeextendedthroughdevicedrivers tomanagenewhardwareì Hardwarevendorswritesoftwaretomanagetheirdevicesì OSprovidesafixedinterface(API)thatdrivermustfollow

ì Commontaskforadevicedriverisrespondingtointerrupts(fromthatdevice)

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Operating Systems – The Kernel

ì Whodoesallthisessentialworkintheoperatingsystem?(besidestheGUI)ì Thekernel (i.e.theheartorcoreoftheOS)

ì Kernelperforms:ì Schedulingì Synchronizationì Memorymanagementì Interrupthandlingì Securityandprotection

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Operating Systems – GUI

ì Operatingsystemswithgraphicaluserinterfaces(GUI)werefirstbroughttomarketinthe1980s

AppleMacOS1.0(released1984)

MicrosoftWindows1.0(released1986)

Capturesfromhttp://www.guidebookgallery.org/screenshots

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ì SignificantevolutioninGUIdesigninsubsequentdecades

Operating Systems – GUI

ì Technicalperspective:ì TheGUIisoneoftheleastimportantpartsofthe

operatingsystem

ì AGUIdoesnotevenhavetobepartofthetrue OSatallì Windows1.0wasjustaprogramthatranontopof

MS-DOS,thetrue operatingsystem(ofthatera)

ì Buttoauser,theGUIisoneofthemostimportantpartsoftheOS!

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Command-LineAdvantagesofCommandLine

AdvantagesofWindows/GUI

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ìLinux Command Line

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Shell

ì Whatistheshell?(e.g.BASH,CSH,SH)ì Programbetweenuserandthekernelì Command-lineinterpreter

ì Parsesuserinputandcarriesoutcommands

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Shell Shortcuts

ì <TAB>keytoauto-completecommands

ì <UPARROW>keytocyclethroughpreviouscommands

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Thesetwotipsmakeyourlifesomucheasier!

Linux: Sudo Command

ì sudo <<command>>

ì Commandisrunasrootuser

ì root=“Administrator”

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http://xkcd.com/149/

Linux: Apt-Get Command

ì Whatisapackagemanager?ì Wheredidtheseappscomefrom?

ì apt-get <<mode>> <<options>>

ì apt-get install gedit

ì Mode=installapackageì Option=Gedit (nameofpackage)

ì MustrunasROOTtouse!ì sudo apt-get …

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Linux: Directory Tree

ì Absolutepath:ì /home/hpotter/thesis/intro.txt

ì Relative path:ì IfIamalreadyin/home/potter/ì addresses.html

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http://osl.iu.edu/~pgottsch/swc2/lec/shell01.html

ìLabs

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Labs

ì Labshave(atmost)twogradedelements:

1. Pre-Lab“checkpoint”– quickverificationthatpre-labappears tobedone1. Dueatstartoffirstdayoflab

2. LabReport1. Submitallsourcecodeusedwithlabreport2. Duebyposteddateafterlab

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Lab Reports

ì Notreally“reports”,morelike“worksheets”

ì CreateinLibreOffice (akaOpenOffice)usingexampletemplateonwebsite

ì ExportinPDFformat

ì Submitì ViaCanvasAssignments sectionforLab1only!ì ViaVersioncontrolforLab2andbeyond

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Upcoming Schedule

ì Todayì Lab1– LinuxBasics

ì Thursdayì Lab2– VersionControl

ì Deadlinesì Lab2pre-labcheckpoint– StartofclassThursdayì Lab1Report– Jan28th,2017by5am

ì SubmitviaCanvasì Lab2Report– Jan30th,2017by5am

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