eeeBook CollectionLinuxShellScriptEntireEbookThisisaProtectedPDFdocument.Pleaseenteryourusernameandpasswordtounlockthetext. Remembermyusernameandpassword.IfyouareexperiencingproblemsunlockingthisdocumentoryouhavequestionsregardingProtectedpdffilespleasecontactaTechnicalSupportrepresentative:IntheUnitedStates:1-877-832-4867InCanada:1-800-859-3682OutsidetheU.S.andCanada:1-602-387-2222Email:technicalsupport@apollogrp.edu.1000-0001-54B2-0005B8F51',%48)6

-2863(9'8-32838,)34)6%8-2+7=78)1)2:-6321)28-RXLMWGLETXIV]SY[MPP9RHIVWXERHSTIVEXMRKW]WXIQW(IJMRIXLI9RM\ERH0MRY\STIVEXMRKW]WXIQW9RHIVWXERHGPEWWMJMGEXMSRWSJWSJX[EVI9RHIVWXERHHEXE9RHIVWXERHXLIYWIVVSPIW9RHIVWXERHFEWMG0MRY\GSQQERHW'VIEXIWLIPPWGVMTXW8he operating system is a set ot sottvare instructions that run the com-puter. Whenyouvriteshellscr iptprograms, youcombineIinuxoperating system commands and programming logic to create automatedtasks. In this chapter, you vill learn about the major operating systems asvellasteaturesspecitictotheIinuxoperatingsystem. YouvilllearnaboutthetypesotusersinaIinuxenvironment, vhichvillhelpyoudeterminethetypeotaccessandtypeotscriptsindividualsneed. SomeotthecommonbasicIinuxcommandsvillbediscussed. Youcanusethese commands in scripts to make a user`sjob easier. linally, to get youstarted vith shell programming, you vill create a tev shell scripts.9NDRS1ANDING3PRA1ING7YS1MSSoftvareisasetotinstructionsthatareprocessedbythecomputersystem. 1heoperating systen is sottvare that governs computer systems. 1he components in acomputer system are the users, the applications, and the hardvare. 1he operating sys-tem acts as a liaison betveen these components. It is the operating system that allovsyou to save a tile to disk, retrieve a tile trom disk, run a spreadsheet application, printa tile, compile a program, point and click vith your mouse, enter text commands, ornavigate the graphical user intertace (GLI,.1hink ot the operating system as the sott-vare brains ot the computer system. ligure 1-1 highlights the relationship betveenthe operating system and the other components in a computer system.1heLerms"soLware"and"prorams"aresynonymousinLhecompuLerindusLry.8MTHardware ComponentsOperaLin sysLemDisk drives Keyboard NoniLor Nouse PrinLer Processor RAN(memory)Users ApplicaLionsfIgure 1-1 Role o Lhe operaLin sysLem2 Chapter 1IntroductIon to the OperatIng System nvIronmentUnderstandIng OperatIng Systems 31here are many ditterent operating systems running many ditterent computer systems bothtorbusinessandhomeuse. Operatingsystemsrunlargemaintramecomputers, server-based netvorks, PC (personal computer, systems, laptops, and even small handheld devices.Mainfrane operating systens are designed to handle the inputoutput (IO,, pro-cessing, and storage requirements tor many users.1hese operating systems run maintramecomputersandaregenerallyusedinlargecorporations. Anexampleotamaintrameoperating system is the IBM Multiple Virtual Storage (MVS, system.Netvorkoperatingsystensallovcomputerstoshareresourcesoveranetvork. Aresource is a hardvare device, a sottvare program, or a tile. A printer that can be used bymultiple users is an example ot a shared resource. In the past a netvork vas detined as agroup ot computers and printers connected by cables. Hovever, vith the advent ot nevertechnology, computersandprinterscancommunicateviavirelesstransmissionasvell.Netvorkoperatingsystemsuseprotocol softvaretotacilitatethecommunicationamongcomputersthroughoutanetvork. 1CPIPisthemostcommonprotocolusedtoday. 1ransnission Control Protocol/Internet Protocol (1CP/IP) allovs you toconnect to the Internet and brovse Web sites, pertorm searches, or shop online. Lach com-puter, called a host, must have an IP (Internet Protocol) address to communicate vithothercomputersonthenetvork. 1hehostmayalsohaveaDonainNaneService(DNS) nane such as Pedhat.com.1his is sometimes called its triendly name.1he DNSname is used so people von`t have to remember the IP address ot a host.In a netvork, servers are computers that allov other computers to connect to the server`sshared resources. Clients are the computers that use the resources made available by theservers. 1heclient/server modelis vhen aserver computerhandlestherequests madeby the client computer.1here are usually more clients than servers in a netvork. Becausethe server has to handle numerous client requests, the server typically has more memory,hard drive space, and processing capability than the clients. Lxamples ot operating systemsthat run on servers are Novell NetWare, Microsott Windovs N1 Server, 2000 Server, andLNIXIinux. Windovs93, Windovs98, WindovsN1 Workstation, Windovs2000Protessional, and Windovs XP are examples ot client operating systems.You can also runLNIXIinux as a client. Servers and clients must use the same protocol in order to com-municate vith one another. Lven it clients are using ditterent operating systems, the useotacommonprotocolallovscommunicationtooccur. Inligure1-2, youcanseetheserver and clients in a netvork environment.1(fINING 1H9NIX AND0INUX3PRA1ING7YS1MS1heLNIXoperatingsystemgoesbacktothe1960s. SeveralemployeesvorkingtorA181 developed an operating system based on the C language and called it LNIX.1heinitial version vas called A181 System Pelease V.1he operating system code vas treelydistributed to major universities vhere changes vere made to it. So, unlike proprietaryoperating systems such as Microsott Windovs, Novell, and IBM, a single vendor has notdevelopedLNIX. 1herehavebeennumerousversionsottheinitialoperatingsystem,and many vendors have customized LNIX to tit their ovn plattorms. IBM has vrittena version ot LNIX called Advanced Interactive Lxecutive (AIX,, Sun has vritten Solaris,andHevlett-PackardhasvrittenHP-LX, andtherearemanyothers. Pecently, sott-varevendorsvhohavetraditionallydevelopedtheirovnoperatingsystemstortheirovn hardvare are beginning to use the Iinux operating system.1he Iinux operating system vas developed trom another version ot LNIX called MINIX.It comes vith many built-in teatures, a tull compliment ot programming languages, com-pilers, and system administration tools, and is available at a very reasonable cost.1able 1-1shovs a listing ot some ot the versions ot the Iinux operating system and the associatedWeb sites tor researching them. 1his book tocuses on the Iinux operating system.ClienL compuLer ClienL compuLer ClienL compuLerServer compuLerfIgure 1-2 ClienL/server model in a neLwork4 Chapter 1IntroductIon to the OperatIng System nvIronmentDefInIng the UnIx and LInux OperatIng Systems 5Iet`s look at some ot the teatures the Iinux operating systems otters.1hey are as tollovsMultiuser capabilityPortability MultitaskingAbility to use multiple processorsMultiple modes ot operationMultIuser CapabIlItyA nultiuser operating system is one capable ot handling multiple requests by a varietyot users. Manycompanies run Iinux as their mainstay operating system tor their busi-ness because it provides a multiple user plattorm. 1hey can install their applications ona Iinux server and have client computers access the application on the server over thenetvork. Some operatingsystemsare single-userplattorms(onlyoneuser canusethecomputer,, such as Windovs 93 and 98.A plaLorm comprises boLh Lhe hardware and soLware combinaLion on which aiven sysLem runs. For example, i Linux version 8.0 is Lhe soLware runnin onan lnLel-based hardware sysLem, Lhen Lhe Lwo combined are called Lhe plaLorm.PortabIlItyPortability allovs you to carry the Iinux operating system to another hardvare system,recompile it, and run the operating system. Ot course, this is alvays easier said than donebecause installing an operating system can be an arduous task. Many operating systemsare vritten tor a specitic processor. Lach processor has its ovn instruction set, vhichis the set ot instructions the processor uses to operate. 1heinstruction setsot ditterentprocessors are typically not compatible.You can think ot an instruction set as being thelanguage specitic to the processor.8MTVersIon Web SIteDebian www.debian.orOpenLinux www.calderasysLems.comSuSe www.suse.comSlackware www.slackware.comNandrake www.mandrake.comRed HaL www.redhaL.com1able 1-1 Versions o Linux and Lheir Web siLes11here are tvo general types ot processors.A conple instruction set conputer (CISC)has a large set ot instructions in its instruction set. A reduced instruction set conputer(RISC) has a reduced number ot instructions in its instruction set but relies on hardvaretopertormthetasksnotprovidedbytheinstructionset. Becauseot theenhancedhard-vare, a PISC processor is taster, yet more expensive, than a CISC processor.1he processorin most PCs is a CISC processor. Windovs 98 runs only on CISC-based Intel processors.Ped Hat Iinux can run on both CISC and PISC processors.1he portability ot the Iinuxoperating system gives you more hardvare options on vhich to run the operating systembecause you can choose to run Iinux on either type ot processor.MultItaskIngMultitasking is vhen the operating system can handle multiple jobs at seemingly the sametime. When a program executes, it is knovn as a job or process. 1echnically, the operatingsystem pertorms only one job at a time. Hovever, through time slicing, the operating sys-tem gives each job a little bit ot time.1he jobs take turns being processed in a round-robinmanner. Iet`slookatanexample. Assumetheoperatingsystemgiveseachjobonlyoneminute ot CPL time. It a job exceeds the one-minute time slice, it is sent to the svap tile.1hen the next job in line begins processing. It this job tinishes in less than a minute, thenthe system can retrieve the next job in the process queue or continue processing the tirstjob that vas sent to the svap tile. 1his is done tor all jobs until there is no more vork tobedone. 1headvantageotthisisthatonelargejoblasting13minutesorsovon`tslovdovn the vhole system and keep smaller jobs that require less processing time trom beingcompleted.1he Iinux operating system employs preemptive multitasking as opposed to cooperativemultitasking.With preenptive nultitasking, the operating system has the ability to takecontrol ot the system trom an application. With cooperative nultitasking, the applica-tion takes control ot the system resources.1he advantage ot preemptive multitasking is thatit an application tails, the vhole system von`t necessarily crash. In cooperative operatingsystems, a tailed application can cause the vhole computer to treeze or crash.AbIlIty to Use MultIple Processors1heabilitytohaveseveralprocessorstoimproveoverallthroughput, ortheamountotvork that can be put through the system, is another advantage ot the Iinux operating sys-tem, and Iinux can accommodate up to 32 processors. Iinux also usesnultithreadingvhich allovs tor a program to be split across several processors, vith each processor vork-ing on a ditterent piece ot the program at the same time.6 Chapter 1IntroductIon to the OperatIng System nvIronmentDefInIng the UnIx and LInux OperatIng Systems 7Synnetrical nultiprocessing (SMP) tacilitates multithreading. SMP greatly enhancesthroughputbecauseseveralprocessorshandleonelargetaskinsteadotasingleprocessorhandling the same task alone. SMP is typical on systems vith a large number ot users vherethroughput demands are great.MultIple Modes of OperatIon 1he Iinux operating system operates in tvo modes. 1hey are as tollovsGraphical user intertace (GLI,1ext GraphIcalUserInterface(GUI)Mode1he GLI program, called X Windovs, otters a Windovs look and teel to the Iinux envi-ronment.What you see on your screen is called the desktop because it includes the toolsyou need to pertorm daily tunctions. Some ot the tools provided as part ot the desktopareaGLItilemanager, aDesktopmanagerandanInternet Webbrovser. ligure1-3shovs a screenshot ot the Iinux Gnome desktop.Linux also ives you access Lo Lhe lnLerneL by uLilizin Lhe necessary hardwareLo run NeLscape CommunicaLor, Web browser soLware, and 1CP/lP.8MTfIgure 1-3 1he Linux Gnome deskLopOpens Lhe Gnome menuWeb browser1ligure 1-4 shovs a screen shot ot the Iinux tile manager open on the desktop.1ext ModeIinux also provides you vith a text mode intertace. In this intertace you use commandsto navigate the Iinux system and vrite your shell scripts. You villneed to use text orgraphicaleditorstovriteshellscriptprograms. ligure1-3shovsascreenshotottheIinux text mode open on the desktop ot the GLI.fIgure 1-5 Linux LexL modefIgure 1-4 Linux ile manaer8 Chapter 1IntroductIon to the OperatIng System nvIronmentUnderstandIng ClassIfIcatIons of Software 9You access the text mode in the Iinux operating system via a shell. Acting as an inter-preter, the shell accepts commands trom the keyboard and either executes the commandor displays an error it the command encounters a problem.1echnically, the shell is a lan-guage, so you must adhere to its syntax, or rules. A tev ot the shells available on Iinuxare listed in 1able 1-2.9NDRS1ANDING'LASSIfICA1IONSOf7Of1WARIt is alvays a good idea to knov vhat sottvare is running on your system.1his vay, youare better equipped to troubleshoot in case a problem occurs. Also, sottvare can be undera sottvare contract, so you may be able to contact someone it problems arise.Sottvare is divided into the tolloving categoriesSystem sottvare Application sottvareSystem SoftwareSystemsottvareincludesthecorecomponentsotthesystemthatmustbepresentinorder tor the computer to operate. Lxamples ot system sottvare are1he kernelob management sottvareMemory management sottvareProgramming languagesDevice driversSottvare utilitiesShell Name DescrIptIonsh 1he oriinal shell wriLLen by SLeven 8ourne, also known as Lhe 8ourne Shellbash Publicly licensed 8ourne-Aain Shell compaLible wiLh Lhe oriinal 8ourne Shell;Lhis is Lhe deaulL shell you eL aL loincsh C-shell which uses a C-like synLaxksh Publicly licensed Korn shell wriLLen by David Korn1able 1-2 Various shell inLerpreLers available on Linux11hekernel1he kernel is the heart ot the operating system.When any computer system boots, a setot program instructions are loaded trom the hard drive and kept in memory. Many pro-grams are kept, or cached, in memory tor speedy access, but the kernel is the core ot anyoperating systemthatoccupiesmemory aslongasthe computer remains on. It controlsall other sottvare activity. Only the most important and videly used programs are part otthe kernel.1he kernel calls upon other programs that are held on disk or in other areas otmemoryby intertacingvithother operatingsystemprogramsvith thehardvare ot thecomputer system. Most operating systems have a kernel that remains in memory. Lxamplesinclude Iinux, Novell NetWare,Windovs N1, Windovs 2000, and Windovs XP.1he kernel is cached in memory. Cachin means Lo keep prorams in mem-ory or quick access. 8ecause memory access is asLer Lhan reLrievin iles roma hard disk or neLwork, cached prorams are reLrieved quicker.Customizing your Iinux kernel allovs you to give your computer system ditterent capa-bilities.You can modity your kernel by adding or removing support ot ditterent teaturessuch as the ones shovn in ligure 1-6.JobManagement It is the tunction ot the operating system to manage processes that are executing. In gen-eral, vhen a program executes it is knovn as a job or process.A daemon is a job LhaL runs in Lhe backround waiLin or work. Nany o LhesysLem prorams are jobs run as daemons.8MTfIgure 1-6 Kernel eaLures you can cusLomize8MT10 Chapter 1IntroductIon to the OperatIng System nvIronmentUnderstandIng ClassIfIcatIons of Software 11Prior to job execution, a job is placed in a job process queue. A job process queue isaholdingareatorthejobvhileitvaitsitsturntorexecution. ArunningprocesshasCPLandmemoryresources boundtoit. 1heIinuxoperating systemusesa processtree to keep track ot the processes on the system. When a program or command exe-cutes, it is assigned a number, called the process ID (PID). 1he PID is used tor inter-nalpurposesbytheoperatingsystem. 1heoperatingsystemusesthePIDvhencommunicatingviththeprocess. 1heprocessnameismuchlikeyourovnnameandthe PID is much like your Social Security number.Lachprocess is created trom a parent. Iinux uses the termspavning to describeoneprocess starting trom another. At times, a process may encounter problems causing it toconsume excessive CPL time or to become orphaned. lor instance, it process A spavnsprocessB, thenprocess Aencountersaproblemandiskilledandremovedtromtheprocess tree, process B, vhich is still running, is said to have been orphaned.MemoryManagement Memorymanagementsottvareallovsyoutomanageallotmemoryincludingbothphysical memoryandvirtualmemory. Virtual nenory istheconceptot thesystemutilizingphysicalmemoryasvellasasectionotharddiskspacetoraccommodatingmultiple processes. 1he use ot virtual memory tacilitates the multiuser and multitaskingteatures and capabilities ot an operating system.1he area on Lhe hard disk reserved or virLual memory is someLimes called Lhepae ile or swap ile. 1heswap ile is creaLed durin Lhe insLallaLion o LheoperaLin sysLem.Hereishovvirtualmemoryvorks. Programsareloadedintophysicalmemory, alsoknovn as randon access nenory (RAM). Programs are allocated a certain amountot time, called a time slice.When memory utilization reaches a certain threshold or vhena process`s time is up, the system sends the program and its data to the hard drive. Heretheprogramisinavaitstateandisplacedtemporarilyonhold. Whenthesystemisreadytoprocesstheprogramanddatathatiscurrentlyonhold, theprogram`sdataissent back to physical memory tor main processing.Maintrameoperatingsystemsandsomenetvorkoperatingsystems, suchasNovellNetWare, LNIX, Iinux, and Windovsplattorms, utilizevirtualmemory. Onevaytospeed up your computer system is to add more memory to it. Another vay is to increasethe size ot your svap tile by allocating more disk space to it.8MT1ProgrammIngLanguagesSottvareprogramsarevritteninlanguagessuchasC, C, ava, VisualBASIC,COBOI, lOP1PAN or Assembly. Ianguages are divided into tvo major classiticationsHigh-levelIov-level HIgh-level ProgrammIng Languages High-level programming languages are designedvith people in mind. 1hey tend to be similar to Lnglish in style and are much easier tortheprogrammertoreadandcomprehendthanlov-levelprogramminglanguages. lorexample, reviev the tolloving excerpt ot a COBOI programming language statementIF HOURS > 40 THEN PERFORM CALCULATE~OVER~TIMEELSE PERFORM CALCULATE~REGULAR~TIMEEND~IFIntheexample, itthehoursexceed40, thenovertimeiscalculated. Itthehoursareunder and including 40, thenregulartimeis calculated. You can clearly seehovthissample COBOI program is very much like Lnglish. Lxamples ot high-level program-minglanguagesinclude Perl, COBOI, C, BASIC, VisualBASIC, andlOP1PAN.High-levelprogramminglanguagesmustbeconvertedtromtheirhuman-readabletorm into computer- or machine-readable torm.1his conversion can be done througheither compiling or interpreting. 1he compiler or interpreter is sottvare that is vrit-ten to pertorm the conversion.With conpiling, the entire program is converted into an executable program. Once itis tree ot errors and compiled, the program is capable ot being run or executed. On manysystems, itisjustamatterotclickinganiconrepresentingtheprogram. Lxamplesotcompiled languages are C, C, COBOI, and lOP1PAN.In the case ot interpreting, each line is converted into machine-readable torm as it isexecuted. 1he statements vithin the program are still converted into machine-readabletorm, it`s just done line by line. 1hink ot an interpretive language as being one vhere aminicompileisdonetoreachstatement. SomeexamplesotinterpretivelanguagesareVisual BASIC (hovever you can compile the code,, Perl, BASIC, and shell programs.Low-levelProgrammIngLanguages Lachprocessorhasitsovnprogramminglanguage, ottencalledalov-levelprogramminglanguage. 1heterm lov-level isusedbecausethelanguageisnativetotheprocessorinsteadotbeingsimilartoLnglish. Lxamples ot these are the Assembly language statementsthat are specitic toeverycomputersystem. So, youcouldnottakean Assemblylanguageprogramand12 Chapter 1IntroductIon to the OperatIng System nvIronmentUnderstandIng ClassIfIcatIons of Software 13run it on just any system. Hovever, you are more likely to take a high-level programandrunitonanothersystemvithmaybeonlyatevmoditications. 1akealookatthe tolloving excerpt trom an Assembly language programL l,XA l,YA l,ZST l,T1he above programming codesimply adds up a set otthree variables, X,Y, and Z, andstores them in avariable named 1. It is not like Lnglish, and it greatly ditters trom theCOBOI program example you sav earlier.DevIceDrIversKeep in mind that it you have a piece ot hardvare, such as a printer or scanner, you musthavesottvarethatgovernsit. Device drivers aresottvareinstructionsthatmanageaparticulardevice. Youmustcontigurethecorrectdrivertorthetypeothardvareyouinstall. Lntortunately, it`snotuncommontoinstalladevicedriverincorrectly. 1akeaprinter driver tor example. A possible symptom ot an incorrectly installed printer driveristhattheprinter`soutputisgarbledandunreadable. Anothersymptomistheprinterprints one line on a page and then advances to the next page to print the next line.Remember, you musL use Lhe device driver LhaL oes wiLh Lhe device. ln oLherwords, i you are usin a brand X, model Y device, you musL use a brand X,model Y device driver or Lhe device will noL uncLion properly.SoftwareUtIlItIesSoftvare utilities are commands that help augment the tunctionality ot the operatingsystem. 1heyareespeciallyimportantbecausetheycanbeusedincombinationvithshell script programming logic to automate certain tasks.1he tolloving are some sottvare utilitiesBackup and restore Compression and uncompression Printer managementackup and Restore One ot the most important aspects ot any job is backing up yourdata.Whether you back it up to a tloppy disk, CD, hard drive, or tape, you should alvaysback up your data. Although many organizations use redundant servers in case one goesdovn, or they use redundant disks storage, they still require their personnel to pertormbackups.8MT1Backups typically occur during ott-hours vhen users are not vorking vith applicationtiles. 1he reason being that it you back up tiles during business hours, you cannot guar-antee the backup has indeed backed up the data that is being processed at that momentby the application. Also, some backup utilities do not backup tiles that are in use.1he restore process is the copying ot the data that vas backed up to either its originalstoragelocationoranotherone. 1he backup andrestoreprocessesshouldbetestedtoverity they vork in case a real emergency ever occurs.CompressIonandUncompressIon Mosteverytilehassomethinginitthatisrepeated. lor example, one ot the most common vords is the vord the, vhich occursin many documents and books, such as this one. Conpression is the process ot remov-ingthose repeatingportionsotatile, therebymakinganev smallertile. Compressionvaries based on the amount ot data that is duplicated and the compression algorithm thatis used.At times, compression can yield betveen a 73 and 90 savings.You vould gen-erallycompressatilethatistobedovnloadedovertheInternet. Ittakeslesstimetodovnloada compressedtilebecauseitissmaller. Anotheradvantage otcompressionisthat it saves disk space because ot the reduced tile size. Hovever, in order to utilize thetile, you must uncompress it tirst.PrInter Management 1he Iinux printing system uses the concept ot print queues totemporarily hold print jobs. When a user sends a print job to a printer, the print job isspooled to a directory tor the printer vhere it vaits.1he Lerm "spool" is an acronym LhaL comes rom l8N mainrame Lerminoloy.lL sLands or SimulLaneous Peripheral OperaLions OnLine.Simply stated, it means the system can send a print job to the printer sottvare concur-rent vith othersystem activities. It the printer is busy or not turned on, the printjobvaits in the print queue until the printer is ready to accept the request.When the printerisreadytoprint, theprintmanagementsottvarelooksintheprinter`sdirectory, orqueue, and prints the next job. It then deletes the print job request trom the print queue.ApplIcatIon SoftwareApplicationsoftvare issottvarethatassistsusersinpertormingtypicalotticevorksuch as vriting letters and business proposals, managing numeric intormation, and orga-nizing large amounts ot data. As such, application sottvare is generally divided into thesemajor categoriesWord processingSpreadsheetDatabase8MT14 Chapter 1IntroductIon to the OperatIng System nvIronmentUnderstandIng ClassIfIcatIons of Software 15Word-ProcessIngSoftwareWord-processingsottvarehasbeenaroundsincetheearly1980s. Word-processingsott-vare allovs you to create, modity, delete, save, and print ottice-quality documents. Word-processing sottvare also includes the enhanced capabilities ot spell checker, dictionary, anda thesaurus.1oday, Microsott makes Word and Sun Microsystems otters a vord-processingpackageaspartottheStar Otticesottvarepackagesuite. Star Otticeruns ontheIinuxoperating system.SpreadsheetSoftwareAlso during the early 1980s, a group ot studentstaking an accounting class grev tiredot making numerous changes to the accounting sheets vhen only one number changed.1hese students eventually started the Iotus Corporation, one ot the tirst companies tocreate spreadsheet sottvare tor PCs. Spreadsheet programs allov you to manage numericdata on a large scale. Spreadsheets hold data in cells, vhich are much like storage loca-tions.When one cell changes, all cells reterencing the original cell also change. Cells arelabeledconsecutivelystartingvithA1andcontinuingastarasyourdatademands.Ietters represent the columns and numbers represent the rovs.Spreadsheet programs are extremely povertul and can include programming logic.1heyalso include built-in tunctions. Functions are miniprograms that do the vork vhen yousupply the data, such as pertorming a mathematical calculation.You will learn how Lo use shell scripL prorams Lo creaLe uncLions in ChapLer 8.In this spreadsheet example, =AVERAGE{Al:A20| you can see the pover ot a spreadsheettunction.1he AVERAGE tunction is given, or passed, tvo valuesthe beginning cell in a cellrange,A1, and the ending cell in a cell range, A20.Whatever values are held in any ot the 20cells in column A are included in the average. It a value in any cell in the range changes, theaverage changes too.DatabaseSoftwareDatabase programs allov you to manipulate and manage data, create tables ot data tor orga-nization, and join or combine data trom multiple tables to create vievs or subsets ot tables.Dataheld in databases can beaccessed quickly viaa unique identitier calleda key tield.Ashton-1ate Corporation developed one ot the tirst database programs on the market torPCs in the 1980s called dBASL. Other companies such as IBM, Microsott, Oracle, and SunMicrosystems have also developeddatabase sottvare. Iinux comes vith a database prod-uct called MySQI. It allovs you to add, delete, and modity data vithin databases.8MT19NDRS1ANDING(A1AIn order to successtully vrite shell script programs, you must understand vhat data is asvell as the structure ot data. Data is made up ot rav tacts that are not much use untiltheyare processedintointormation. Considerthe number 73. 1his isconsidered data.You cannot look at the number 73 and tell it it is an exam grade, the outdoor temper-ature, orsomeone`sage. Onlyvhenaprogram, inconjunctionviththecomputer`sprocessor, processes the number can it become intormation. 1he programmer`s job is tovrite programcode toturn datainto usetulintormation. 1hinkotdata asahierarchyor a pyramid. ligure 1-7 shovs the data pyramid.At the lovest level ot the data hierarchy are bits.1he term bit stands tor binary digit andis either a zero (0, or a one (1,. Lach computer system has a character set that maps allthe letters on the keyboard to its appropriate bit sequence. American Standard Code torIntormationInterchange(ASCII,isacharactersetcommonamongmostcomputerenvironments including all Windovs operating systems and the Iinux operating system.Although you don`ttypically use anything as smallas abit in your daily dealingsvithcomputers, you do need to understand the concept.In the computer industry, the term byte reters to eight bits taken in sequence. Anothersynonymtorthetermbyteisalphanumericcharacter. Analphanumericcharacterisdetinedasanyottheletters AthroughZ, numbers0through9, andspecialsymbols.Althoughitisuponenotchonthedatahierarchy, acharacterisgenerallythelovestlevel ot the data hierarchy that people process.Records:1asha Liu, 400 Yona Dr., 8eijin, ChinaFred SmiLh, 201 Apple Lane, ALlanLa, GA, 30033Fields: 1asha Liu, Lires8yLes: A 8 7 9 ; > z8iLs: 0 0 1 1 0 0 1 0Files:Payroll.daLlnvenLory.daLfIgure 1-7 DaLa pyramid16 Chapter 1IntroductIon to the OperatIng System nvIronmentUnderstandIng Data 17A group ot bytesis called a field. lor example, it you`ve ever tilledout a job or collegeadmission application, or even your 1040 tax torms, you knov that you must till in littleboxes or blank lines vith your personal data. Lach ot the boxes or blank lines is enteredinto an application screen to be processed by a program. 1hese boxes and blank lines areconsidered tields. lields are labeled, or given names, so that you may reter to the data con-tained vithin them. lor instance, a tield called NAML, may have the tolloving data1ashaIui. It you vanted to print the NAML tield, it vould print the name 1asha Iui. Noticealso that a tield is comprised ot characters or bytes.A group ot related tields makes up a record. lor example, consider the employee recordscontaining the tield names and data shovn in 1able 1-3. 1here are three records vith sixtields each. In this case, you can think ot a record as a rov and think ot a tield as a column.In most application systems, there is one unique identitying tield in a record called theprinary key field. 1his tield is used to access the remaining tields in the records. 1hepurpose ot the primary key is to locate the data in the record etticiently. When a banktellerasks you toryourbank accountnumber, theaccount number is usedas the pri-mary key.Your Social Security number is used as a primary key vhen you till out yourtax returns or an employment application.1o help you understand the primary key concept, think about hov the index in the backot this book vorks. It you vant to look up a term, you go to the index and look throughthe alphabetical listing until you locate the page number reterence tor the term. 1hen,you go to the actual page number that describes the term.1he primary key is analogoustothetermyouseekintheindex. Inanapplication, theprimarykeytieldisusedtolocate the record containing the rest ot the data.A grouping ot related records is called a file. A tile has a name and location tor vherethe data is housed. A tile can contain tvo major types ot data, executable, or binary data,and nonexecutable data.Lecutable or binary files are tiles that havebeen compiled and pertormsome typeotoperationortask. 1heyarevrittenusingtexteditorstollovingthestrictsyntaxotthe language and then they are compiled.1he compilation process creates the executablecode. 1he commands that you`ll use in this book are executable tiles.Name Address CIty State ZIp PhoneSarah 1oar 214 ScoLL Way Concord NH 03301 555-5550Xin Chun Liu 428 Aubrey Way Lilburn GA 30047 555-5551Nolly Obakin 1027 Nichelle Lane 1ulsa OK 74101 555-55571able 1-3 Sample employee records1Noneecutable files are generally data that the executable tiles operate on.1he user runsan application or program that creates data tiles. Data tiles can also be created automaticallyby programs that run vithout user intervention. Lxamples ot nonexecutable tiles are texttiles, vord-processing document tiles, spreadsheet tiles, database tiles, or picture tiles.9NDRS1ANDING9SR6OLSIntheIinuxcomputing environment, thereareseveraltypesotusers, eachvithdit-tering roles. Lnderstanding the role ot a user is important because it helps you decidethe type ot shell scripts that person might need on the job. Additionally, the role gov-erns the type ot access the user has to the system. Here is a list ot the typical user typesStandard userSystem Administrator or root userShell programmerStandard Users 1he standard user, sometimes just called user, is the person vho uses the Iinux oper-ating system on a daily basis. Lsers may also have access to commands via the text modeandotherprogramsintheGLI. 1heyalsousethesystemtoaccessapplications. 1heapplications theyneeddependupontheir tunctions intheorganization. Considerthisexample ot typical users` needs. An accounting manager may need access to the account-ingapplication, anengineermayneedaccesstoacomputeraideddesigncomputeraided manutacturing (CADCAM, program, an insurance agent may need access to theinsurance adjustment application, and a travel agent may need access to the travel book-ing application.Lsers access the Iinux system by logging in using a user account. Generally, a computerspecialist, such as a System Administrator vho has authority to create the accounts, gen-erates the useraccounts. 1he user account should also havea passvord that is assignedto it. Once the users log in, they usually set their ovn passvords.System AdmInIstrator 1he Systen Adninistrator is a computer specialist vho is responsible tor the operationsot the computer systems and netvork. Depending upon the size ot the operation, there maybe more than one System Administrator in an organization.1hey are completely responsi-ble tor ensuring that the systems, the netvorks, and the applications are available to the usersduring the hours needed by the users.System Administrators pertorm a variety ot tasks including upgrading applications andinstallingsystemsottvare, changinguserpassvords, monitoringthenetvorktorbot-tlenecks, and in some cases, changing printer toner cartridges. Some have to be on call24 hours a day to provide support tor multiple shitt operations.18 Chapter 1IntroductIon to the OperatIng System nvIronmentUnderstandIng User Roles 19System Administrators also maintain security, making sure users have the right access toapplication tiles and tolders on the computer system. 1he goal is to give each user justvhat is needed to do the job, but no more.At times, a System Administrator may have to log in to a special user account that hastheabilitytopertormsystemadministrativevork, suchasaddaprintqueue, changeanother user`spassvord, or backupa system tile, standarduser accountsdon`thave theability to do these things. In Iinux, the name ot the user vith complete administrativecapability is called root.1he root user has access to programs and contiguration tiles thatstandard users don`t.You musL use cauLion when loin in as Lhe rooL user because you can deleLeormodiyconiuraLionilesandproramsLhaLareunrecoverablewiLhouLcompleLely reinsLallin Lhe operaLin sysLem.Dependingupontheorganization, theSystemAdministratormayberesponsibletorvriting shell scripts, or the responsibility could be relegated to a shell programmer.Shell Programmer A shell progranner is responsible tor vriting shell scripts.A shell script is a program thatis vritten to automate a process in the Iinux operating system. A shell programmer vritesthe script using an editor, tests the script, and vhen the script passes the tests, makes the scriptavailable to users.1he shell programmer must have an understanding ot programming con-cepts as vell as the Iinux commands in order to successtullyvrite scripts. lor example, ashell programmer may need to vrite a script that uses system commands and decision logictor a System Administrator vho needs a vay to automate the backup process. Or a shell pro-grammermayneedtocreateamenusoseveraluserscanrunIinuxcommandsvithoutentering the complete syntax ot the command.1ypically, a shell programmer logs in using aregular user account unless the task requires them to use the root user account.At times a shell programmer may have to debug scripts or remove any syntax or logicerror trom scripts or programs.A synta error is one that does not contorm to the rulesot the language. An example ot asyntax error is a misspelled command. A compiler orinterpreter usually displays an error message vhen it encounters a syntax error. A scriptor programcan not run untilit is syntax-error tree. Shell programmers must learn thesyntax ot the shell to prevent syntax errors.1he Lerm debu was coined in Lhe 1940s when a moLh shorL-circuiLed elec-Lrical componenLs in a mainrame compuLer sysLem causin a sysLem ailure.8y removin Lhe moLh, Lhe sysLem was "debued."A logicerror isanerrorthatdoesnotmeettherequirementsottheprogramminglogic as decided upon by the users and management. 1hese are typically more ditticulttortheshellprogrammertoidentitybecausethescriptsaremostlikelysyntactically8MT1correct.1he compiler or interpreter does not display a message indicating the error andtheprogramappearstorunnormally. Anexampleotalogicerrorvouldbeusingaless-than symbol instead ot a greater-than symbol in an overtime calculation script. Inthe tolloving set ot COBOI statements, a logic error occurs because the less-than sym-bol is used in place ot the greater-than symbol. In the example, a person vorking morethan 40 hours vill have their pay calculated on regular time. 1he program vould runbecausetheuseot theless-thansymbolissyntacticallycorrect, buttheoutputotthecodevouldbeundesirable. ComparethisexampletotheearlierCOBOIexamplevhere use ot the greater-than symbol (> 40, is logically correct.IF HOURS < 40 THEN PERFORM CALCULATE~OVER~TIMEELSE PERFORM CALCULATE~REGULAR~TIMEEND~IF9NDRS1ANDING&ASIC0INUX'OMMANDS1he Iinux operating system contains numerous commands. Some are only available toSystem Administrators and not to standard users, vhile other commands are available toeveryone.You need to learn about the commands that are available to all users becausethey may also be used in shell scripts.LoggIng In and LoggIng OutOne ot the tirst things you need to knov is hov to log in to the Iinux system.You needa username and passvord. (1o complete the activities and projects in this book, you mayneed to ask your instructor tor your username and passvord.,1here are tvo vays ot logging in to a Iinux system. lirst, you can physically sit in trontot the system and enter you username and passvord. Second, you can use the telnetcommand to log in to the Iinux system. 1his requires the host to have an IP address orDNS name.Next you vill log in using the second method just discussed.You vill use the ping com-mand to verity the Iinux computer is accessible on the netvork and the telnet commandto connect to it it it is.You vill access the Iinux system trom a Windovs-based system thatis running 1CPIP.1o verify the Linu host is accessible and connect to the Linu systen if it is:1. Start Windovs on your computer (any version ot Windovs vill vork,.2. Click the Start button, and then click Run. 1he Pun dialog box opens.3. 1ype command, and then click OK. 1he Windovs command prompt opens.20 Chapter 1IntroductIon to the OperatIng System nvIronmentUnderstandIng asIc LInux Commands 214. 1ype ping hostnameZhostaddress, and then press Lnter. Be sure tosubstitute your correct host`s name or IP address. It the command succeeded,you should see a Peply trom message. It so, proceed to Step 6.3. It you received an error, such as Pequest timed out, it means the host isinaccessible. See your instructor. Do not go to the next step.6. 1ype telnet hostnameZhostaddress, and then press Lnter. Be sure tosubstitute your correct host`s name or IP address. 1he Iinux login promptappears. ligure 1-8 includes the logging-in process to the Iinux system tromthe Windovs command prompt.7. 1ype your usernane, and then press Lnter.Your username appears on thescreen, and you are prompted tor a passvord.8. 1ype your passvord, and then press Lnter.Your passvord vill not appear onthe screen tor security reasons.You have nov successtully logged in and haveaccess to the Iinux system.9. 1o log out, type logout, and then press Lnter.Your connection to theIinux host is terminated, and you return to the Windovs command prompt.AnoLher way Lo lo ouL is Lo press CLrl+D insLead o Lypin logout.1heGEP CommandOnce you`ve successtully logged in to the Iinux system, you can use other Iinux com-mands. 1he cal command displays the current calendar month. Hovever, you can usethe cal command to display a variety ot months and years. Here is the general tormatot the commandcal month yearfIgure 1-8 Loin in Lo a Linux sysLem rom a Windows-based PC8MT11he month is an optional number betveen one and 12 representing the numeric num-ber tor the month.You can only display the month it you include the year option.1heyear is an optional number betveen one and 9999 retlecting the year. So, tor example,it you vant to display the current month`s calendar, you vould run this command cal.1o display the calendar tor the vhole year, you vould run the cal command vith theyearonly. lorexample, the tollovingstatement displaysthecalendar torthetirstninemonths tor the year 2004.cal 2004ligure 1-9 shovs the partial calendar tor the year 2004.1heGEX Command1he cat command allovs you to display the contents ot text tiles very easily. You sim-plytypeinthecommandtollovedbythetilename, thetextdisplaysonyourscreen.Atter the command completes its task, your prompt returns.1he cat command is derived trom the term concatenate vhich means to join or tusetogether. 1he cat command concatenates the contents ot a tile on your disk vith thescreen. 1he command takes the tolloving tormcat ot1on f11enameHere is an example that displays the contents ot the sales tilecat salesfIgure 1-9 1he resulLs o Lhe cal2004 command22 Chapter 1IntroductIon to the OperatIng System nvIronmentUnderstandIng asIc LInux Commands 231he cat commandnotonlyallovsyoutodisplaytextonthescreen, butalsoallovsyou to create a tile. 1o do this you use the greater-than redirection operator, >. At thispoint, all you need to understand is that the output ot the cat command is redirectedto a tile instead ot your screen. 1his results in the creation ot a nev tile.1he concepL o redirecLion will be ully discussed in ChapLer 4. Next you vill create a tile using the cat command and the redirection operator, and thendisplay the tile`s contents.1o redirect tet to a file using the cat connand:1. Iog in to the Iinux system as a user.2. Pight-click a blank area ot the desktop, and then click Nev 1erninal. 1he1erminal emulation program vindov appears vith your prompt.3. 1ype cat > file2.txt, and then press Lnter. Notice that the cursor movesto the beginning ot the next line and that there is no prompt on that line.4. 1ype the tolloving code exactly as it is shovn, being sure to press Lnter atthe completion ot each lineShell Programming will help me on the job.Linux is fun!WhencreaLinailewiLhLhe cat command,onceyou'vepressedLnLer aLLhe end o a line, you cannoL o back Lo LhaL line and ediL iL. CreaLin a ileusin Lhe cat command is or quick Lasks. 1o ediL Lhe ile, you need Lo use oneo Lhe ediLors discussed laLer in Lhis chapLer.3. Press Ctrl+D to send an end-ot-tile (LOl, character to the cat command.1he cursor moves to the next line and your prompt returns.6. 1o display the contents ot the tile, type cat file2.txt, and then pressLnter. ligure 1-10 shovs the contents ot the tile you just created as vell asyour creation ot that tile.7. 1o exit the vindov, type exit, and then press Lnter.8. Iog out.2SXI8MT11heHEXI Command1he date command displays or sets the system date and time. Here is the general syn-tax ot the commanddate ot1on +format1able 1-4 provides a listing ot available tormats tor the date command.OptIon DescrIptIon xample%D Displays Lhe daLe in NN/DD/YY ormaL; Lhis is where NN is Lhedate +%DLwo-diiL monLh, DD is Lhe Lwo-diiL day, and YY is Lhe lasL Lwo diiLs o Lhe year%d Displays Lhe Lwo-diiL day date +%d%Y Displays Lhe our-diiL year date +%Y%H Displays Lhe Lwo-diiL hour date +%H%h Displays Lhe Lhree-leLLer monLh date +%h%T Displays Lhe Limedate +%T% Displays Lhe numeric day rom 001 Lo 366; Lhis is someLimes calleddate +%Lhe Julian daLe%m Displays Lhe Lwo-diiL monLh date +%m1able 1-4 OpLions or Lhe date commandfIgure 1-10 1he cat command Lo creaLe a ile24 Chapter 1IntroductIon to the OperatIng System nvIronmentUnderstandIng asIc LInux Commands 25ligure 1-11 shovs a screenshot ot the date command run using various tormats shovnin 1able 1-4.1heIGLS CommandYou use the echo command to display text on the screen. As such, the echo commandis a very usetul debugging tool that can help you troubleshoot shell script programs.1heecho command takes the torm ot the tollovingecho "Text to d1s1ay"While not required on all versions ot Iinux, on some versions you do need the quotes.Hovever, it is good practice to enclose text that includes spaces in quotes.You vill learnmore about use ot quotes in Chapter 3. Consider this exampleecho "How are you doing?"You can use the echo command to create a tile. Hovever, using the echo command todo this is only recommended vhen you only need a small tileconsisting otjust a tevlines. 1odothisyouusethegreater-thanoperator, >, toredirecttheoutputtromthescreen to a tile. Pedirection vill be discussed in Chapter 4.In the tolloving example, the output ot the echo statement is sent to a tile called salesecho "March sales exceed proections for the Houston Branchoffice." > salesNext you vill use the echo command to redirect text to the sales tile, and then use thecat command to display the contents ot the tile.fIgure 1-11 1he date command run wiLh dierenL ormaLs11o redirect tet to a file using the echo connand:1. Iog in to the Iinux system as a user.2. Pight-click a blank area ot the desktop, and then click Nev 1erninal. 1he1erminal emulation program vindov appears vith your prompt.3. 1o redirect the output to a tile named sales, type the tolloving code, andthen press Lnterecho "March sales exceed projections for the Houston Branchoffice." > sales1he command executes but returns no output to the screen because theoutput is redirected to the sales tile.4. 1o display the contents ot the sales tile to your screen type cat sales.ligure 1-12 shovs a screenshot ot the creation ot the sales tile using theecho command and it`s displayed using the cat command.3. 1o exit the vindov, type exit.6. Iog out.1heLMWXSV] CommandItyouvanttoseethecommandsyou`vealreadyentered, youcanrunthehistorycommand.1his command is usetul tor saving keystrokes.You can use your up and dovnarrovstogoupanddovnthroughyourhistorylisttolocateacommandyouprevi-ously entered. Once you locate the command you can use the backspace key to modityit, or you can press Lnter to rerun the command as is.fIgure 1-12 1he echo command used Lo creaLe Lhe sales ile26 Chapter 1IntroductIon to the OperatIng System nvIronmentUnderstandIng asIc LInux Commands 27Here is the general tormat ot the command historyhistory ot1onItyouenterthehistorycommandvithoutanyoptions, itdisplaysthelast1,000commandsyou`veentered. Lsedvithoutanyoptions, itcanprovideyouvithmoreintormation than you may be prepared to deal vith. Here are a tev vays you can usethe history command.1he history command teature allovs you to enter a recently executed command byplacing the ! operator prior to the command. So, to rerun the most recently executedcal command, enter!calYou don'L have Lo enLer Lhe compleLe command when usin Lhe ! operaLor.For example, i you enLered, !da, Lhe mosL recenLly execuLed command LhaLbeins wiLh Lhe leLLers "da" is execuLed. l Lhe date command was Lhe mosLrecenLly execuLed command, Lhen iL would be rerun.1he history command displays numbers to the lett ot each command in its list. It you seea command in the history list that you vant to rerun, you can enter the ! operator tollovedby the number ot the command in the list. So, to rerun the 1031WXcommand in the list, enter!l03lligure 1-13 shovs a screenshot ot running the history command using the ! operator.fIgure 1-13 1he history command usin Lhe ! operaLor8MT11hePTV Command1he lpr command places a tile in the print queue tor printing.You use this commandto send a document to the printer.1he tormat ot the command lpr islpr ot1on f11ename1o print the sales tile you created in an earlier exercise, you enter the tolloving codelpr salesAlthough the lpr command prints to the detault printer set up by the System Administrator,it can also be used to print to a specitic printer using the ~P option. lor example, to printthe sales tile to a printer named IinuxPrinter, enter lpr ~P LinuxPrinter sales.NosL commands allow you Lo enLer opLions. However, because each commandhas a dierenL uncLion, Lhe ormaLs o Lheir opLions are usually dierenL. For LhemosL parL, an opLion is preceded by eiLher one or Lwo dashes, as in ~t.1heQER Command1he man command allovs you to display the manual, or help, pages tor a command.Yourun this command to see a description ot a command and its options, it it has any. 1hegeneral torm isman command1ousetheman commandtodisplaythemanualpagestortheecho command, enterman echo. ligure 1-14 shovs a screenshot ot the man pages tor the echo command.fIgure 1-14 1he manecho commandDeLails Lhe opLions used byLhe commandSummarizes Lhe commandand any opLions ordaLa neededName o Lhe commandollowed by a shorLdescripLion8MT28 Chapter 1IntroductIon to the OperatIng System nvIronmentUnderstandIng asIc LInux Commands 291heXSYGL Command1he main purpose ot the touch command is to update the moditication date and timestamp ot a tile.1his is particularly usetul vhen vriting shell script programs. lor example,it you had a shell script program that ran overnight or anytime vhen you veren`t avail-able to check on it, you can ensure the script ran or the tile vas updated by running thetouch command tor the tile. 1he touch command takes the tolloving tormtouch f11enameYou can also use the touch command to create an empty tile and set the moditicationdate and time on that tile using the same torm.1he[LS Command1he who command allovs you to display the list ot users vho are currently logged onto the Iinux system. 1he torm ot the command is as tollovswho ot1onsYou can also display a count ot the total number ot users logged in using the ~q option.ligure 1-13 shovs a sample screenshot ot both the who and who ~q commands.fIgure 1-15 1he who and who~q commands1Peter to 1able 1-3 tor a listing ot the common basic Iinux commands.'RA1ING7HLL7CRIP1SBecause the shell is a command interpreter that makes use ot programming capabilities,it allovs you to use traditional programming concepts. Here are some ot the traditionalprogramming concepts the shell allovs you to pertorm vith scriptsMake decisions based upon conditionsPertorm arithmetic operationsCreate a menu using looping statementsLse tunctions to pertorm very specitic tasksManipulate data using an array1he Lerms "scripL" and "proram" are synonymous.A shell script pertorms one other tunction that traditional programming languages do nottypically support, the shell script runs operating system commands. Iike other programminglanguages, you vrite your shell script, and then you execute it. Next you vill create a sim-ple shell script.8MTCommand DescrIptIoncal Displays a calendarcat Displays Lhe conLenLs o a ileclear Clears Lhe screendate Displays or seLs Lhe daLe and Limeecho Displays LexLhistory Displays previously enLered commandslogin and logout Allows you Lo lo in and lo ouLlpr PrinLs a ileman Displays manual (help) paes or a commandping DeLermines i anoLher 1CP/lP sysLem is availabletelnet ConnecLs Lo a 1CP/lP compuLertouch UpdaLes Lhe modiicaLion daLe and Lime o a ilewho Displays Lhe currenLly loed on users1able 1-5 8asic Linux commands30 Chapter 1IntroductIon to the OperatIng System nvIronmentCreatIng Shell ScrIpts 311o create and eecute a sinple shell script:1. Iog in to the Iinux system as a user.2. Pight-click a blank area ot the desktop, and then click Nev 1erninal. 1he1erminal emulation program vindov appears vith your prompt.3. 1ype cat > script1, and then press Lnter to create a tile called script1.4. 1ype the tolloving code to add text to script1echo "Welcome to my shell script."echo "This is one of my first shell scripts!"echo "Shell script programming is a tool for helping users automate their tasks."3. Press Crl+D to terminate the line.Your prompt returns.6. 1o execute the script, type bash script1, and then press Lnter.Yourscreen should look like ligure 1-16 vhich shovs the script you have input asvell as the resulting output.7. 1o exit the 1erminal emulation program, type exit, and then press Lnter.8. Iog out.1oreintorcevhatyou`vealreadylearnedaboutusingcommandsandcreatingshellscripts, next you vill create a shell script that displays the calendar tor the current month,the current time on the screen, and the usernames ot the users currently logged in.fIgure 1-16 scripL1 and resulLin ouLpuL11o create a shell script vhich displays the calendar, the current tine, and theusernanes of those users currently logged in:1. Iog in to the Iinux system as a user.2. Pight-click a blank area ot the desktop, and then click Nev 1erninal. 1he1erminal emulation program vindov appears vith your prompt.3. 1ype cat > script2, and then press Lnter to create a nev tile namedscript2.4. 1ype cal, and then press Lnter to include the current calendar.3. 1ype date, and then press Lnter to include the current date.6. 1ype who, and then press Lnter to display the users that are currently loggedin. Press Crl+D to terminate the line. 1he prompt returns.7. 1o execute the script, type bash script2, and then press Lnter.Yourscreen should look like ligure 1-17 vhich displays the script you have inputas vell as the resulting output.8. Pecord the output.9. 1o exit the 1erminal emulation program, type exit, and then press Lnter.10. Iog out.fIgure 1-17 scripL2 and resulLin ouLpuL32 Chapter 1IntroductIon to the OperatIng System nvIronmentChapter Summary 33'HAP1R7UMMARY1he operating system is the sottvare brains that manage the computer system.1he operating system interacts vith users, the applications, and the hardvare. Allcomputer systems must have an operating system in order tor the system to run.1he Iinux operating system is a portable, multiuser, multitasking, and multiprocessingsystem. Iinux supports both a graphical user intertace (through the use ot X Windovs,or a text mode intertace.1here are numerous versions ot Iinux in the marketplace.1he Iinux shell interprets shell scripts.Sottvare can be classitied into systems sottvare and application sottvare. Systemsottvare includes the kernel, job management sottvare, memory management sott-vare, and device drivers. System utilities include backup and restore sottvare, com-pression and uncompression sottvare, tile system management sottvare, and printermanagement sottvare. 1he kernel is the nucleus ot the operating system. It remainsin memory and controls other sottvare components.Data is made up ot rav tacts. Intormation is processed data. A bit is either a binaryzero or one. A byte is a group ot eight bits. A tield is a group ot bytes. A record is agroup ot tields. A primary key tield is a special tield that allovs you to quicklyaccess a record in a tile. A tile is a group ot records. 1here are tvo types ot tilesexecutable, or binary, and nonexecutable. Lxamples ot executable tiles are com-mands and programs. Lxamples ot nonexecutable tiles are picture tiles or text tiles.It is important to understand the user roles in a Iinux environment so you can cre-ate appropriate scripts and access to the system tor the user. A standard user is aperson vho uses the application and system on a daily basis to pertorm a certainjob tunction such as payroll, accounting, marketing, tinance, or engineering. ASystem Administrator is responsible tor maintaining, monitoring, upgrading, andtroubleshooting the system and netvork so users can do their jobs. A shell pro-grammer vrites shell programs tor users. Shell programmers apply their knovledgeot programming logic and Iinux commands to create scripts tor users.Iinux allovs you to interact vith the operating system via commands.1here are liter-ally hundreds ot commands. Most have multiple options that augment the command insome vay.You use the manual pages tor the command you vant to learn more about.Shell script programming combines programming logic structures vith operatingsystem commands to automate routine tasks. 1he shell runs commands in the shellprogram.16VIW5US1IONS1. is the sottvare that remains in memory and controls otheractivity.a. Kernel b. Sottvare utilitiesc. Backup sottvared. ob management sottvare2. Shell script programs usually run in themode ot Iinux.a. X Windovsb. MS Windovsc. graphicald. text 3. Which ot the tolloving is an interpreted languagea. COBOIb. Cc. Cd. Bourne-Again Shell (bash,4. A spreadsheet is an example otsottvare.a. backupb. application c. print management d. assembly language3. A group ot tields is also knovn as a.a. byteb. characterc. record d. table6. Hov many bits are in a bytea. 1b. 2c. 4d. 8 34 Chapter 1IntroductIon to the OperatIng System nvIronmentRevIew QuestIons 357. What company tirst developed LNIXa. Microsottb. Iinuxc. Ped Hatd. A181 8. is another name tor a process.a. ob b. Disk drivec. lolderd. X Windovs9. Which command allovs you to display the manual pages tor a commanda. manb. pagesc. whod. lpr10. When vas LNIX developeda. 1960sb. 1970sc. 1980sd. 1990s11. Which command allovs you to display the tvo-digit daya. date +%Yb. date +%Tc. date +%dd. date +%D12. is rav tactsa. Intormationb. obc. Data d. Daemon113. is a background job.a. Intormationb. obc. Datad. Daemon 14. 1hecommand sends a document to the printer.a. lprb. printitc. dated. echo "Hi" > file4.txt13. Ais a group ot related records.a. tieldb. tilec. bitd. character16. Ais a person vho uses the system on a daily basis to do hisspecitic job, such as manutacturing, accounting, or payroll.a. System Administratorb. standard userc. shell programmerd. daemon 17. Ais a person responsible tor making sure the systems and net-vorks are available to the users vhen needed.a. System Administratorb. standard userc. shell programmerd. job18. A picture tile is an example ot atile.a. binaryb. executablec. nonexecutabled. job management36 Chapter 1IntroductIon to the OperatIng System nvIronmentHands-on Projects 3719. A command is an example ot atile.a. binaryb. nonexecutablec. print queued. X Windovs20. Ais a person vho vrites scripts as his or her main job tunction.a. System Administratorb. standard userc. shell programmerd. print queue,ANDSON4ROJC1SProject 1-1Inthis project, you vill visit an organizationthat uses the Iinux operating system anddiscussthetypeothardvareandsottvareituses. You`llalsorecordittheorganizationuses any scripts, and it so, tor vhat purpose.1. Iocate an organization that uses the Iinux operating system as the main operatingsystem tor their organization.2. Pecord the name ot the organization.3. Interviev one ot the System Administrators or other persons responsible tor thecomputer system. Pecord the type ot hardvare used.4. Pecord the version ot Iinux used.3. Pecord the application sottvare used.6. Pecord the shell interpreter used by their users.Project 1-2In this project, you vill visit various Iinux vendor Web sites and record your tindings.1o complete this project, you vill need Internet access.1. Open your Web brovser, then go to the redhat.con Web site.2. Spend some time brovsing this Web site.3. Pecord intormation about cost, hardvare requirements, sottvare version, andproduct otterings ot the Ped Hat version ot Iinux.,ERHWSR4VSNIGX,ERHWSR4VSNIGX14. Change the address location to the calderasystens.conWeb site.3. Spend some time brovsing this Web site.6. Pecord intormation about cost, hardvare requirements, sottvare version, andproduct otterings ot the Iinux version ottered by Caldera.7. Change the address location to the nandrake.conWeb site.8. Spend some time brovsing this Web site.9. Pecord intormation about cost, hardvare requirements, sottvare version, andproduct otterings ot the Iinux version ottered by Mandrake.Project 1-3In this project, you vill execute basic Iinux commands to help you understand hov tointeract vith the operating system shell.1. Iog in to the Iinux system as a user.2. Open a 1erminal emulation vindov.3. 1ype who, and then record the output.4. 1ype cal, and then record the output.3. 1ype date, and then record the output.6. 1ype history, and then record the output.7.1ype !# vhere = is a number in the history list ot a command you vant to execute.8. Pecord the command that vas used.9. Lse the up and dovn arrov keys to scroll back and torth in the history list otrecently executed commands, and press Lnter to execute a command.10. Pecord the command.11. 1o exit the 1erminal emulation program, type exit.12. Iog out.Project 1-4In this project, you vill execute ditterent variations ot the commands to help you under-stand hov to run commands using ditterent options.1. Iog in to the Iinux system as a user.2. Open a 1erminal emulation vindov.3. 1ype date +%h, and then record the output.4. 1ype date +%T, and then record the output.3. 1ype date +%m, and then record the output.6. 1ype who -g, and then record the output.,ERHWSR4VSNIGX,ERHWSR4VSNIGX38 Chapter 1IntroductIon to the OperatIng System nvIronmentHands-on Projects 397. 1ype cal month year vhere month is your tvo-digit birth month and ear isyour tour-year birth year, and then record the day ot the veek you vere born on.8. 1o exit the 1erminal emulation program, type exit.9. Iog out.Project 1-5In this project, you vill vrite a small shell script to display text on the screen.1. Iog in to the Iinux system as a user.2. Open a 1erminal emulation vindov.3. 1ype cat > Project1-5.4. 1ype the tolloving code to insert text into the Project1-3 scriptecho "Welcome to my shell script."echo "This is one of my first shell scripts."echo "Shell script programming is a tool for helping SystemAdministrators."3. Send an end-ot-tile (LOl, character to the cat command.6. 1o execute the script, type bash Project1-5.7.1o print your script to the detault printer, type lpr Project1-5. It you don`t haveaccess to a printer, record vhat displays on the screen on a separate sheet ot paper.8. 1o exit the 1erminal emulation program, type exit.9. Iog out.Project 1-6Inthisproject, youvillvriteashellscripttodisplaythecurrentuliandateandthenumber ot users currently logged in.1. Iog in to the Iinux system as a user.2. Open a 1erminal emulation vindov.3. 1ype cat > Project1-6.4. 1ype date +%j.3. 1ype who -g.6. Send an end-ot-tile (LOl, character to the cat command.7. 1o execute the script, type bash Project1-6.8. Pecord the output.9. 1o print your script to a specitic printer, type lpr ~P printer-name Project1-6 vhere printer-name is the name ot the printer.You mayhave to get the printer name trom your instructor.,ERHWSR4VSNIGX,ERHWSR4VSNIGX110. Close your 1erminal emulation vindov.11. Iog out.Project 1-7In this project, you vill use the manual pages to help you locate a particular option.1.Iog in to the Iinux system as a user, and then open a 1erminal emulation vindov.2. 1ype man cat.3. Iocate the option to number all output lines, and then record the letter torthat option.4. 1o use the option, type cat ~option Project1-6 vhere option is the letteryou recorded in the previous step. (Iine numbers display to the lett ot the com-mands in the previous script tor the previous project.,3. 1ype man lpr.6.Pead through the man pages and tind a nev option tor the lpr command that hasnot been discussed in this chapter, and then record the option and its description.7. 1ype man touch.8. Pead through the man pages and tind an option tor the touch command, andthen record the option and its description.9. Pun the command using the option you chose, and then record the commandand the option you chose.10. Close your 1erminal emulation vindov.11. Iog out.Project 1-8Inthis project, you vill createa scriptcontaining threestatements. Youvill insert dit-terent versions ot the date command using various options.1.Iog in to the Iinux system as a user, and then open a 1erminal emulation vindov.2. Lse the cat command to create a tile named Project1-8. (HintYou need to usethe redirection symbol.,3. Lsing the correct option trom 1able 1-4, insert the date command so it displaysthe date in MMDDYY tormat.4. Lsing the correct option trom 1able 1-4, insert the date command so it onlydisplays the current time.3. Send an end-ot-tile (LOl, character to the cat command.6. Display the contents ot the Project1-8 script, using the cat command.7. Pecord the contents ot the script.8. Lxecute the script using the bash command.,ERHWSR4VSNIGX,ERHWSR4VSNIGX40 Chapter 1IntroductIon to the OperatIng System nvIronmentCase Projects 419. Print your script. It you do not have access to a printer, record vhat displays onyour screen on a separate sheet ot paper.10. Pecord the command needed to print the script.11. Close the 1erminal emulation vindov.12. Iog out.'AS4ROJC1SCase 1-11MI Corporation is currently running maintrame computers in a distributed environment.1hereareabout23usersconnectingviadumbterminalstothemainottice, locatedinIavrenceville, Georgia.1hey use manutacturing, inventory, and personnel applications vrit-ten in COBOI. 1heir programmers are villing to learn other languages but have not yethadthechancebecausethey`vebeentoobusymaintainingthecurrentapplications. 1hecompany has outgrovn its computing resources. It is in the process ot selecting an entirelynev computer systemtrom hardvare to sottvare.Writeaproposaltothecompany`schietintormationotticer(CIO,convincinghertochoosetheIinuxoperatingsystem. Includespeciticationstorthe 1MICorporation,accounting torenough computers to service the current number otusers, tvo servers,andtiveprinters. Indicatetheprogramminglanguagethenevapplicationsshouldbevritteninandsupportyourdecision. IncludearationaletorsendingtvoSystemAdministrators to attend Iinux administration classes.Case 1-2 1heDaisyMae WooHaberdasheryCorporationcurrentlyisrunningaproprietaryLNIX operating system trom the XYZ Corporation vendor. 1he XYZ Corporation isgoingoutotbusinessbecauseotadovnturnintheeconomy. 1heDaisyMae WooHaberdashery`s business is thriving, but they are vorried about the potential lack ot sup-portinthetuture. 1heDaisyMae WooHaberdasheryhastiveremoteotticeslocatedvithin 10 miles ot its main ottice.1he Daisy Mae Woo Haberdashery has tinancial appli-cationsrunninginCandmanyottheSystem Administrationtoolsare vrittenintheBourne Shell. Many times, the sottvare locks up the computer system causing it to halt.So, a nev operating system is needed. 1he current version ot LNIX is compatible vithversions ot MINIX.1he Daisy Mae Woo Haberdashery Corporation has decided to go vith a nev vendor,theAlphalirm, torconsultingservices. Writeaproposalto 1heDaisyMae WooHaberdasheryCorporation asit you vere a vice president tor the Alphalirm. IncludeinyourproposalvhichversionotIinuxyouvouldrecommend, theshellyouvouldsupport, and hov you vould go about migrating the current programs to the nev sys-tem. Detend your decision on paper.'EWI4VSNIGXW'EWI4VSNIGXW143',%48)6

92()678%2(-2+8,)0-29. 1hetollovingexamplesorts a tile namedunsort.datandplaces the outputtoanev tile named sort.dat.1he original tile remains intact.1here is no output to the screenbecause it is being redirected to atile. 1he name ot the tile tolloving the greater-thansymbol is user detined.sort unsort.dat > sort.datBy detault, the sort command sorts in ascending order, or lover to higher.You can sortin descending order, called reverse order, using the ~r option as in this commandsort ~r f11ename1heGYX Command1he cut command allovs you to strip text out ot tiles and display the cut text on the screenor redirect the text to another tile. 1his command is most otten used to cut tields vithin atile.1he data is not permanently cut trom the tile.1he command does not alter the originaltile and it automatically opens the tile tor you.1he basic syntax tor the cut command iscut ot1onsf11enameYouneed to be avareottvo importantoptions. 1he~d optionis used toidentitythedelimiterinthetile. 1hecolonisgenerallyusedasaseparatorordeliniter betveentields, lettingprogramsknovvhereonetieldbeginsandoneends. lorexample, ~d:identities the colon as a delimiter.1he ~f option is used to identity vhich tield you vantbased on the delimiter. lor example, consider the tolloving record tor an animal clinicl00l:King Pup:Dog1he tirst tield,1001, represents the ID, the second tield,King Pup, represents the ani-mal`s name, and the third tield, Dog, represents the type ot animal. Colons are used todelimit the tields in this example.You use a colon, or some other character, instead ot aspace to separate tields.1he space can not be used because it may actually separate vordsin a tield, such as King Pup.Assumingthetileisnamedanimal.dat, thecommandtodisplaythetirsttieldiscut ~d: ~fl animal.dat.1he command to display the tirst and third tields vould becut ~d: ~fl,3 animal.dat.2Next you vill create a tile vith several employee records in it. Lach record vill consistot tvo tieldsan employee number tolloved by a colon and the employee name.1o use the cut connand in a file:1. Iog in to the Iinux system as a user, and then open a 1erminal emulation vindov.2. Create a tile named unsort.dat using the vi editor.3. Lnter the data in tvo tields. Note in the data belov, that the tormat isnum|er.name vhere num|er represents the tirst tield and name represents thesecond tield. 1he colon (, is the delimiter. Place the tolloving data in the tilenoting that there are duplicate 3:Jessie records. (You vill use these tvorecords later vhen you learn about the uniq command., Atter you enter thedata make sure you press Lnter at the end ot each line, save the tile, and thenexit the vi editor.3:Jessie James Garcia3:Jessie James Garcia2:Zachary Scott Pheng4:Lorenzo Todd Von Schloss1:Micki McSunday-Washington4. 1o cut the tirst tield, type cut -d: -f1 unsort.dat, and then pressLnter. See ligure 2-13, the tirst tield appears on your screen, but the data hasnot been removed trom the original tile.3. 1o cut the second tield, the names, and then send the output to a tile namedname.dat, type cut -d: -f2 unsort.dat > name.dat, and then pressLnter. See ligure 2-13.6. 1o display the contents ot the nev tile, type cat name.dat, and then pressLnter. See ligure 2-13, notice that the nev tile only has the names in it.7. 1o ensure that the original contents ot unsortcut.dat have not been literally cut,type cat unsort.dat, and then press Lnter.1he original contents that verecreated in Step 3 appear unchanged on your screen as shovn in ligure 2-13.8. 1o exit, type exit, and then press Lnter.9. Iog out.68 Chapter 2UnderstandIng the LInux fIle SystemUnderstandIng fIle Management Commands 691heTEWXI CommandWhereas the cut command cuts tile tields, the paste command pastes, or merges, datatrom one tile to another. 1he data can then be merged into a nev tile.1he basic syntaxot the paste command ispaste f11ename_onef11ename_two1heabovecodemergeseachlinetromtiletvovitheachlineottileone. lorexample,assumeyouhadtvotileseachcontainingnamedata. 1helast.dattilecontentsareSmith Jones Adams, and the tirst.dat tile contents are Joe Mary Sue. It you enter thecommand paste first.dat last.dat, then your output to the screen vould beJoe SmithMary JonesSue AdamsItyouhadenteredthecommandpaste last.dat first.dat, thenyouroutputvould beSmith JoeJones MaryAdams Sue1he contents ot the original tiles remain the same.You can also create an altogether nevtileusingtheredirectoutput(>,symbol. Ityouenterthecommandpaste first.dat last.dat > first_last.dat, youvouldcreateanevtilecalled tirst_last.dat vith the pasted data trom the tirst.dat and last.dat tiles.fIgure 2-13 DemonsLraLin Lhe cut command1he oriinal ile's conLenLs1he oriinal ile's conLenLsunchaned1he second ield cuL andplaced in anoLher ile;noLice Lhe new ile onlyhas names in iL1he irsL ield cuL rom Lheile is noL acLually removed2Suppose that Mama`s Hardvare Store maintains tvo separate tiles. One tile is called productand contains the names ot top selling sale items, and the other tile is called quantity and con-tains the amount ot the sales items that have been ordered.1he ovners vould like the intor-mation to appear in one tile named orders.1o do that, you need to paste these tiles together.ligure 2-14 shovs the contents ot the tvo original tiles as vell as the use ot the paste com-mand to merge these tiles and redirect the contents to the nev tile.1heVQ Command1he rm command is used to remove a tile permanently trom the tile system tree hier-archy. 1here is no vay to recover a removed tile. 1he basic syntax ot the command isrm f11enameIn the tolloving example, the tile named resume.dat is removed.rm resume.datSome versions o Linux ask you Lo veriy LhaL you really wanL Lo remove a ilebeoreiLisremoved.OLherversionssimplyremoveLheilewiLhouLaskin.Use cauLion and consider LesLin Lhis concepL by removin a LesL ile beoreremovin any iles rom your ile hierarchy.fIgure 2-14 1he paste command or Nama's Hardware SLoreConLenLs o quanLiLy ileConLenLs o orders ileusin pasteDeaulL display o merinquanLiLy and producL ilesusin pasteConLenLs o producL ile70 Chapter 2UnderstandIng the LInux fIle SystemUnderstandIng fIle Management Commands 711heYRMU Command1he uniq command is to used to tind duplicate lines trom a sorted tile. 1his is a partic-ularly helptul programming technique to use it redundant records happen to exist in a tile.1he uniq commanddoesnotremovetheduplicatelines, itjustdisplaysthemonthescreen.1he uniq command opens the tile tor you. 1he basic syntax ot this command isuniq f11ename1heoutputdetaultstothescreen, displayingtheduplicates. Youcanalsoredirecttheoutput to a user-detined tilename using the tolloving commanduniq duplicates.dat > uniq.datIn this case, the repeating lines trom the duplicates.dat tile are redirected to the uniq.dattile.You use redirection vhen you vant to reter to the original data tile. In this case, youvouldprocesstheuniq.dattilebecauseanyredundantrecordshavealreadybeenremoved trom the tile.1he uniq command has a usetul option tor counting the number ot occurrences ot a linein a tile. 1his is helptul vhen you vant to identity the number ot duplicates you have ina tile.1he tolloving uniq command vith the attached ~c option accomplishes thisuniq ~c duplicates.datNextyouvillusetheuniq commandtoremoveduplicateitemstromagrocerylistvhere several people in the household have added redundant items.1o use the unig connand to renove duplicates fron a file:1. Iog in to the Iinux system as a user, and then open a 1erminal emulation vindov.2. Create a tile named grocery.dat using the vi editor.3. Lnter the tolloving data. As you enter the data, make sure you press Lnter atthe end ot each line. Save the tile, and then exit the vi editor.soupsouppizzaturkeylettucelettucelettuceapplesbananasgrapesgrapes24. 1o remove the duplicate grocery items, type unig grocery.dat, and thenpress Lnter. See ligure 2-13.3. 1o redirect this to a tile that you can take to the grocery store, type unig grocery.dat > list.dat, and then press Lnter.6. 1o display the contents ot the nev list, type cat list.dat, and then pressLnter. See ligure 2-13. Notice that nov the items are part ot the list.dat tile.7. 1o exit, type exit, and then press Lnter.8. Iog out.fIgure 2-15 OuLpuL o Lhe uniq commandSLep 6SLep 4 resulLs ouniq command72 Chapter 2UnderstandIng the LInux fIle SystemRevIew QuestIons 73'HAP1R7UMMARY1he Iinux tile system is designed tor storage and quick access. Directories containother directories or tiles. liles contain only data. 1he Iinux tile system is hierarchi-cal, or treelike, in nature. In the Iinux tile system, the root directory (, is the topot the tree. All tiles and tolders branch trom the root directory. 1he system directo-ries are created during the installation ot the Iinux operating system, and theyshould not be moditied or deleted.When navigating the tree hierarchy, you need to be avare ot vhere you are, orvhat your current directory is. With the hierarchy structure, there is a parent-childrelationship. 1he parent directory is reterred to as dot dot ( .. ,. A child directoryis reterred to by name. Siblings have the same parent. A tull path begins at the rootdirectory. A partial path does not include the root directory.Directory management commands deal vith manipulating and displaying the direc-tories in the tree. 1he most commonly used commands are cd tor changing thecurrent directory location, pwd tor displaying the current directory location, and lstor displaying the contents ot a directory.Lditors and editor commands allov you to manipulate the contents in a tile.1he mostcommonly used editor is vi. It can be used to add, copy, delete, insert, or modity datavithin a tile.1he tile management commands allov you to manipulate the actual tiles vithin thetree. 1he cp command is used tor copying an existing tile to another tile, creatingtvo tiles. 1he mv command is used tor moving or renaming an existing tile, hov-ever, you end up vith just one tile vhen you use this command. 1he rm is used toremove a tile.6VIW5US1IONS1. Lse thecommand to change directory locations.a. cdb. rmc. mkdird. cut2. Which ot the tolloving are considered tull paths (Choose all that apply.,a. dirAb. ..dir2c. payrolld. 23. Lse thecommand to delete a directory.a. delete_dirb. mkdirc. rmdird. cat4. Which ot the tolloving are considered partial paths (Choose all that apply.,a. dirAb. ..dir2c. payrolld. 3. Which ot the tolloving are text editors (Choose all that apply.,a. vib. emacsc. lsd. cat6. 1hecommand sorts data in descending order.a. sort ~rb. sortc. mkdird. reverse7. 1o change the vorking directory location to a sibling directory named dir2, youenter thecommand.a. cd /b. cd \c. cd ..\dir2d. cd ../dir28. 1hedirectory holds mounted drives.a. rootb. bootc. mnt d. var74 Chapter 2UnderstandIng the LInux fIle SystemRevIew QuestIons 759. 1hetile system holds tiles and directories that vary in size.a. rootb. bootc. mnt d. var10. 1hecommand creates a directory named vinchester in theroot directory.a. mkdir /winchester b. mkdir ../winchester c. mkdir \winchester d. md /winchester 11. 1heoption tor the ls command displays a long listing.a. ~ib. ~ac. ~ld. ~c12. Which ot the tolloving represents your parent directorya. ..b. .c. d. 13. 1hecommand allovs you to change directory locations to achild directory named child1.a. mkdir childlb. cd ../childlc. cd childld. cd /14. In vi, the command to change to insert mode isa. ob. Oc. id. d213. 1hecommand deletes a tile.a. rmdirb. cdc. rmd. pwd16. 1hecommand displays your present vorking directory.a. catb. cdc. touchd. pwd17. 1hesystem directory contains the Iinux kernel.a. bootb. rootc. devd. var18. 1hein the vi editor allovs you to save and quit the program.a. :wqb. q!c. w!d. !19. 1he command to rename a tile is.a. mvb. cpc. deld. rename20. 1hecommand makes a duplicate ot a tile.a. mvb. cpc. deld. rename76 Chapter 2UnderstandIng the LInux fIle SystemHands-on Projects 77,ANDSON4ROJC1SProject 2-1In this project, you vill compare your ovn tamily tree to the Iinux tile system. Pesearchyour tamily tree no turther than your grandparents. Drav your tamily tree on a separatepiece ot paper, and then explain hov your tamily tree compares to vhat you`ve learnedabout the Iinux tile system in this chapter.Project 2-2Inthis project, youvill compare a building`s evacuation plan toroneroomto the useot paths in the Iinux tile system.You vill tirst need to get a copy ot a building evacua-tion plan tor one room trom your local church, school, or vork. 1hen, vrite a descrip-tion ot hov the evacuation plan relates to a path in the Iinux tile system hierarchy.Project 2-3In this project, you vill execute various commands in your home directory.1.Iog in to the Iinux computer as a user, and then open a 1erminal emulation vindov.2. 1ype touch file1.dat, and then press Lnter.3. Pepeat Step 2 three additional times, hovever, change the number at the end otthe tilename each time, e.g., tile2.dat, tile3.dat, tile4.dat.4.Create a hidden tile by typing touch .hiddenfile.txt, and then press Lnter.3. Issue a long listing ot all the tiles in the directory by typing ls -al, and thenpress Lnter.6. On a separate sheet ot paper, label and identity each column that is displayed.7. Close your vindov, and then log ott.Project 2-4In this project, you vill search the Ped Hat Web site tor intormation on various Iinuxcommands inordertolearnhovto usethe Web siteasaresearchtool. You vill needaccess to the Internet.1. Open a Web brovser.2. In the Address or location box on your brovser, type hiip//uuu.rehai.com, andthen press Lnter. 1he Ped Hat Web site appears.,ERHWSR4VSNIGX,ERHWSR4VSNIGX,ERHWSR4VSNIGX,ERHWSR4VSNIGX23. In the Search Ped Hat text box, type ls, and then click the Go button. 1hescreen displays a listing ot the links to documents related to the ls command.4. Click one ot the documents and reviev it. Keep checking documents until youlocate one that gives you additional insight into the ls command.3. Based on your tindings at this Web site, identity something nev you`ve learnedabout the ls command.6. Pepeat Steps 3 through 3 tor the pwd command.7. Pepeat Steps 3 through 3 tor the cp command.8. Pepeat Steps 3 through 3 tor the vi editor.9. Close your Web brovser.Project 2-5In this project, you vill execute commands, and then drav the resulting tree structure.1.Iog in to the Iinux system as a user, and then open a 1erminal emulation vindov.2. 1ype mkdir Project2-5, and then press Lnter.3. 1ype cd Project2-5, and then press Lnter.4. 1ype mkdir R, and then press Lnter.3. 1ype mkdir S, and then press Lnter.6. 1ype mkdir T, and then press Lnter.7. 1ype cd T, and then press Lnter.8. 1ype touch t1.dat, and then press Lnter.9. 1ype touch t2.dat, and then press Lnter.10. 1ype touch t3.dat, and then press Lnter.11. 1ype cd ../R, and then press Lnter.12. 1ype touch r1.dat, and then press Lnter.13. 1ype touch r2.dat, and then press Lnter.14. 1ype cd ../S, and then press Lnter.13. 1ype touch s1.dat, and then press Lnter.16. 1ype touch s2.dat, and then press Lnter.17. 1ype cd .., and then press Lnter.18. Drav the resulting tree structure.19. Close your vindov, and then log out.,ERHWSR4VSNIGX78 Chapter 2UnderstandIng the LInux fIle SystemHands-on Projects 79Project 2-6Inthis project, you vill create adirectory treebased on the output ot the tree com-mand shovn in ligure 2-16.1.Iog in to the Iinux system as a user, and then open a 1erminal emulation vindov.2. Create the directory tree shovn in ligure 2-16.You need to use these commandsto complete this project cd, pwd, mkdir, and rmdir.3. Pecord the order in vhich you used each command to create the tree.4. Close your vindov, and then log out.Project 2-7In this project, you vill create the directory shovn in ligure 2-17 in order to reintorceyour understanding ot the Iinux tile system hierarchy.You vill need to use these com-mandstocompletethisproject cd, pwd, mkdir, andrmdir. linally, recordthecom-mands in the order in vhich you used them to create the tree.,ERHWSR4VSNIGXfIgure 2-16 1ree you will creaLe or ProjecL 2-6,ERHWSR4VSNIGX2Project 2-8Inthis project, you vill use the treestructure trom Project 2-3 to manipulate the tilesand directories created. Project 2-8 requires completion ot Project 2-3.1.Iog in to the Iinux system as a user, and then open a 1erminal emulation vindov.2. 1ype cd Project2-5, and then press Lnter.3. 1ype cd T, and then press Lnter.4. 1ype ls, press Lnter, and then record the output.3. 1ype cp t1.dat t11.dat, and then press Lnter.6. 1ype cp t2.dat t22.dat, and then press Lnter.7. 1ype ls, press Lnter, and then record the output.8. 1ype mv t3.dat t33.dat, and then press Lnter.9. 1ype ls, press Lnter, and then record the output.10. Pecord the ditterence betveen the cp and mv commands.11. 1ype cd ../S, and then press Lnter.12. 1ype ls, press Lnter, and then record the output.13. 1ype cp s1.dat ../R/r5.dat, press Lnter, and then record vhat this com-mand does.14. 1ype cd ../R, and then press Lnter.13. 1ype ls, press Lnter, and then record the output.16. Close your vindov, and then log out.,ERHWSR4VSNIGX$HONLwaLer Lreesoceans seasaLl.daL pac.daL Red.daLOak.daL Pine.daL8lack.daL.birds.daLfIgure 2-17 1ree you will creaLe or ProjecL 2-780 Chapter 2UnderstandIng the LInux fIle SystemHands-on Projects 81Project 2-9In this project, you vill use vi to create a data tile vith records.You vill then sort the data.1.Iog in to the Iinux system as a user, and then open a 1erminal emulation vindov.2. 1ype mkdir Project2-9, and then press Lnter.3. 1ype cd Project2-9, and then press Lnter.4. 1ype vi infile.dat, and then press Lnter. 1he vi editor opens.3. 1o insert text, press Lsc, and then type i.6. Lnter the tolloving text and make sure you press Lnter at the end ot each line.(Lach rov is considered an employee record vith colons separating the tields. 1hetirst tield is the employee number. 1he second tield is the employee name, and thethird tield is the employee salary.,401:Sue Fanglee Tuen:$34000104:Sammy Jones:$55402207:Tammy Phang:$50040214:Zoe Buhari-Jones:$56000505:James Brongan:$505007. 1o save the tile, press Lsc, and then type the colon symbol (:,. 1he cursor movesto the bottom ot the screen vith a colon to its lett.8. 1o vrite the tile, type wg!, and then press Lnter. 1he prompt returns.9. Sort the data in ascending order by typing sort infile.dat, press Lnter, andthen record the output.10. Sort the data in descending order by typing sort -r infile.dat, pressLnter, and then record the output.11.Sort the data in descending order and redirect the output to another tile by typingsort -r infile.dat > reverse_sort.dat, and then press Lnter.12. Sort the data in ascending order, redirect the output to another tile, and thenrecord the command you used.13. Close your vindov, and then log out.Project 2-10In this project, you vill use the tiles created in Project 2-9. Project 2-10 requires com-pletion ot Project 2-9.1.Iog in to the Iinux system as a user, and then open a 1erminal emulation vindov.2. 1ype cd Project2-9, and then press Lnter.3. Cut the tirst tield.4. Cut the second tield.3. Cut the third tield.,ERHWSR4VSNIGX,ERHWSR4VSNIGX26. Cut both the tirst and third tield and redirect the output to a nev tile namedsalary.dat.7. Make a duplicate ot intile.dat by typing cp infile.dat infile2.dat, andthen press Lnter.8. Open the tile named infile2.dat, and add tive additional records. Add a sixthrecord that has your name. Also, create a tictitious employee number andemployee salary to complete your record.9.1ype diff infile.dat infile2.dat, and then press Lnter. Pecord the output.10. Close your vindov, and then log out.'AS4ROJC1SCase 2-1You have been hired by 1MI to design an application using shell script programs. 1MIneeds you to design and create a nev directory structure.1he company has several departments accounting, sales, manutacturing, intormation tech-nology, andheadquarters. 1heaccountingdepartmenthasaccountsreceivable, accountspayable, andpayrolltunctionsvithinit. 1hemanutacturingdepartmentruns threeshittsand a veekend shitt.1he intormation technology department has tive projects in progress.1he sales department has ottices located in the West, Last, North, and South.lirst, designtheIinuxtilesystemhierarchyonpaper. Keepinmindthatthedepart-ments, tunctions, shitts, regions, and projects need to translate into directories. Next, youneed to create this hierarchy on the Iinux system. Create at least one empty tile in eachdirectory. Lsethedepartment, tunction, shitt, region, orprojectnameasthetilenameand include an extension ot .dat.Case 2-2ZonkaCorp. hassalesotticesintivecountries theLnitedStates, Canada, Spain,Singapore, and lrance. Design your directory structure on paper and then implement it.Make sure that each country is represented by a directory. Next, create tvo tiles in eachdirectory named tirst.dat and last.dat.1hese vill be used to hold employees` names vithan employee`s tirst and last names split betveen tvo tiles. In the tile named tirst.dat, addthetirstnameottiveemployees. Inthetilenamedlast.dat, addthecorrespondinglastname ot the same tive employees.1hen, using the paste command, merge the tirst tvotiles together into a nev tile. lor each employee, the nev tile must have the tirst nametolloved by the last name on one line. 1hen, merge the tirst tvo tiles into another tile.lor each employee, this tile must have the last name tolloved by the tirst name on oneline. linally, make backup copies ot the nevly merged tiles.'EWI4VSNIGXW'EWI4VSNIGXW82 Chapter 2UnderstandIng the LInux fIle System83',%48)6

7,)00&%7-'7-RXLMWGLETXIV]SY[MPP9RHIVWXERHXLIWLIPPPSKMRERHPSKSYXJMPIW0IEVREFSYXWLIPPZEVMEFPIW&IGSQIJEQMPMEV[MXLXLIWLIPPIRZMVSRQIRX0IEVREFSYXWLIPPFYMPXMRGSQQERHW0IEVREFSYXWLIPPKVEQQEV9RHIVWXERHGSQQERHX]TIW8he Iinux shell is the program that acts as the intertace betveen you andthe operating system kernel. 1he shell accepts input in the torm ot yourcommands, and then gives the commands over to the processor tor execu-tion. You see evidence ot the shell vhen you log in and go to a commandprompt. In this chapter, you vill learn hov the shell is executed and under-stand thepurpose otthe shelland shellgrammar. Pedirection villalsobediscussed.9NDRS1ANDING1H7HLL0OGINAND0OGOU1*ILSWhenyoulogin, ashellisexecutedandprovidesyouvithashellprompt. Youtypeyour commands to the right ot the prompt. lrom your previous experience, you knovthatyouneedausernametologinandinteractviththeoperatingsystem. Hovever,vhen auser account is created, it is givena detault shell, vhichis vhat allovsyou toaccess the operating system. lor Ped Hat Iinux, the detault shell is bash.AsyouknowromChapLer1,Lhereareseveraldi