英文文献原文译文Linux.docx

英文文献原文译文Linux.docx

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英文文献原文译文Linux

1.1.History

1.1.1.UNIX

InordertounderstandthepopularityofLinux,weneedtotravelbackintime,about30yearsago...

Imaginecomputersasbigashouses,evenstadiums.Whilethesizesofthosecomputersposedsubstantialproblems,therewasonethingthatmadethisevenworse:

everycomputerhadadifferentoperatingsystem.Softwarewasalwayscustomizedtoserveaspecificpurpose,andsoftwareforonegivensystemdidn'trunonanothersystem.Beingabletoworkwithonesystemdidn'tautomaticallymeanthatyoucouldworkwithanother.Itwasdifficult,bothfortheusersandthesystemadministrators.

Computerswereextremelyexpensivethen,andsacrificeshadtobemadeevenaftertheoriginalpurchasejusttogettheuserstounderstandhowtheyworked.ThetotalcostofITwasenormous.

Technologicallytheworldwasnotquitethatadvanced,sotheyhadtolivewiththesizeforanotherdecade.In1969,ateamofdevelopersintheBellLabslaboratoriesstartedworkingonasolutionforthesoftwareproblem,toaddressthesecompatibilityissues.Theydevelopedanewoperatingsystem,whichwas

simpleandelegant

writtenintheCprogramminglanguageinsteadofinassemblycode

abletorecyclecode.

TheBellLabsdevelopersnamedtheirproject"UNIX."

Thecoderecyclingfeatureswereveryimportant.Untilthen,allcommerciallyavailablecomputersystemswerewritteninacodespecificallydevelopedforonesystem.UNIXontheotherhandneededonlyasmallpieceofthatspecialcode,whichisnowcommonlynamedthekernel.ThiskernelistheonlypieceofcodethatneedstobeadaptedforeveryspecificsystemandformsthebaseoftheUNIXsystem.Theoperatingsystemandallotherfunctionswerebuiltaroundthiskernelandwritteninahigherprogramminglanguage,C.ThislanguagewasespeciallydevelopedforcreatingtheUNIXsystem.Usingthisnewtechnique,itwasmucheasiertodevelopanoperatingsystemthatcouldrunonmanydifferenttypesofhardware.

Thesoftwarevendorswerequicktoadapt,sincetheycouldselltentimesmoresoftwarealmosteffortlessly.Weirdnewsituationscameinexistence:

imagineforinstancecomputersfromdifferentvendorscommunicatinginthesamenetwork,orusersworkingondifferentsystemswithouttheneedforextraeducationtouseanothercomputer.UNIXdidagreatdealtohelpusersbecomecompatiblewithdifferentsystems.

ThroughoutthenextcoupleofdecadesthedevelopmentofUNIXcontinued.MorethingsbecamepossibletodoandmorehardwareandsoftwarevendorsaddedsupportforUNIXtotheirproducts.

UNIXwasinitiallyfoundonlyinverylargeenvironmentswithmainframesandminicomputers（notethataPCisa"micro"computer）.Youhadtoworkatauniversity,forthegovernmentorforlargefinancialcorporationsinordertogetyourhandsonaUNIXsystem.

Butsmallercomputerswerebeingdeveloped,andbytheendofthe80's,manypeoplehadhomecomputers.Bythattime,therewereseveralversionsofUNIXavailableforthePCarchitecture,butnoneofthemweretrulyfree.

1.1.3.CurrentapplicationofLinuxsystems

TodayLinuxhasjoinedthedesktopmarket.Linuxdevelopersconcentratedonnetworkingandservicesinthebeginning,andofficeapplicationshavebeenthelastbarriertobetakendown.Wedon'tliketoadmitthatMicrosoftisrulingthismarket,soplentyofalternativeshavebeenstartedoverthelastcoupleofyearstomakeLinuxanacceptablechoiceasaworkstation,providinganeasyuserinterfaceandMScompatibleofficeapplicationslikewordprocessors,spreadsheets,presentationsandthelike.

Ontheserverside,Linuxiswell-knownasastableandreliableplatform,providingdatabaseandtradingservicesforcompanieslikeAmazon,thewell-knownonlinebookshop,USPostOffice,theGermanarmyandsuch.EspeciallyInternetprovidersandInternetserviceprovidershavegrownfondofLinuxasfirewall,proxy-andwebserver,andyouwillfindaLinuxboxwithinreachofeveryUNIXsystemadministratorwhoappreciatesacomfortablemanagementstation.ClustersofLinuxmachinesareusedinthecreationofmoviessuchas"Titanic","Shrek"andothers.Inpostoffices,theyarethenervecentersthatroutemailandinlargesearchengine,clustersareusedtoperforminternetsearches.Theseareonlyafewofthethousandsofheavy-dutyjobsthatLinuxisperformingday-to-dayacrosstheworld.

ItisalsoworthtonotethatmodernLinuxnotonlyrunsonworkstations,mid-andhigh-endservers,butalsoon"gadgets"likePDA's,mobiles,ashiploadofembeddedapplicationsandevenonexperimentalwristwatches.ThismakesLinuxtheonlyoperatingsystemintheworldcoveringsuchawiderangeofhardware.

1.2.Theuserinterface

1.2.1.IsLinuxdifficult?

WhetherLinuxisdifficulttolearndependsonthepersonyou'reasking.ExperiencedUNIXuserswillsayno,becauseLinuxisanidealoperatingsystemforpower-usersandprogrammers,becauseithasbeenandisbeingdevelopedbysuchpeople.

Everythingagoodprogrammercanwishforisavailable:

compilers,libraries,developmentanddebuggingtools.ThesepackagescomewitheverystandardLinuxdistribution.TheC-compilerisincludedforfree,allthedocumentationandmanualsarethere,andexamplesareoftenincludedtohelpyougetstartedinnotime.ItfeelslikeUNIXandswitchingbetweenUNIXandLinuxisanaturalthing.

IntheearlydaysofLinux,beinganexpertwaskindofrequiredtostartusingthesystem..Itwascommonpracticetotellabeginninguserto"RTFM"（readthemanuals）.Whilethemanualswereoneverysystem,itwasdifficulttofindthedocumentation,andevenifsomeonedid,explanationswereinsuchtechnicaltermsthatthenewuserbecameeasilydiscouragedfromlearningthesystem.

TheLinux-usingcommunitystartedtorealizethatifLinuxwasevertobeanimportantplayerontheoperatingsystemmarket,therehadtobesomeseriouschangesintheaccessibilityofthesystem.

1.2.2.Linuxfornon-experiencedusers

CompaniessuchasRedHat,SuSEandMandrakehavesprungup,providingpackagedLinuxdistributionssuitableformassconsumption.Theyintegratedagreatdealofgraphicaluserinterfaces（GUIs）,developedbythecommunity,inordertoeasemanagementofprogramsandservices.AsaLinuxusertodayyouhaveallthemeansofgettingtoknowyoursysteminsideout,butitisnolongernecessarytohavethatknowledgeinordertomakethesystemcomplytoyourrequests.

Nowadaysyoucanlogingraphicallyandstartallrequiredapplicationswithoutevenhavingtotypeasinglecharacter,whileyoustillhavetheabilitytoaccessthecoreofthesystemifneeded.Becauseofitsstructure,Linuxallowsausertogrowintothesystem:

itequallyfitsnewandexperiencedusers.Newusersarenotforcedtododifficultthings,whileexperiencedusersarenotforcedtoworkinthesamewaytheydidwhentheyfirststartedlearningLinux.

Whiledevelopmentintheserviceareacontinues,greatthingsarebeingdonefordesktopusers,generallyconsideredasthegroupleastlikelytoknowhowasystemworks.Developersofdesktopapplicationsaremakingincredibleeffortstomakethemostbeautifuldesktopsyou'veeverseen,ortomakeyourLinuxmachinelookjustlikeyourformerMSWindowsorMacIntoshworkstation.Thelatestdevelopmentsalsoinclude3DaccelerationsupportandsupportforUSBdevices,single-clickupdatesofsystemandpackages,andsoon.Linuxhasthese,andtriestopresentallavailableservicesinalogicalformthatordinarypeoplecanunderstand.

1.3.DoesLinuxhaveafuture?

1.3.1.OpenSource

TheideabehindOpenSourcesoftwareisrathersimple:

whenprogrammerscanread,distributeandchangecode,thecodewillmature.Peoplecanadaptit,fixit,debugit,andtheycandoitataspeedthatdwarfstheperformanceofsoftwaredevelopersatconventionalcompanies.Thissoftwarewillbemoreflexibleandofabetterqualitythansoftwarethathasbeendevelopedusingtheconventionalchannels,becausemorepeoplehavetesteditinmoredifferentconditionsthantheclosedsoftwaredeveloperevercan.

TheOpenSourceinitiativestartedtomakethiscleartothecommercialworld,andveryslowly,commercialvendorsarestartingtoseethepoint.Whilelotsofacademicsandtechnicalpeoplehavealreadybeenconvincedfor20yearsnowthatthisisthewaytogo,commercialvendorsneededapplicationsliketheInternettomakethemrealizetheycanprofitfromOpenSource.NowLinuxhasgrownpastthestagewhereitwasalmostexclusivelyanacademicsystem,usefulonlytoahandfulofpeoplewithatechnicalbackground.NowLinuxprovidesmorethantheoperatingsystem:

thereisanentireinfrastructuresupportingthechainofeffortofcreatinganoperatingsystem,ofmakingandtestingprogramsforit,ofbringingeverythingtotheusers,ofsupplyingmaintenance,updatesandsupportandcustomizations,etcetera.Today,Linuxisreadytoacceptthechallengeofafast-changingworld.

1.3.2.Tenyearsofexperienceatyourservice

WhileLinuxisprobablythemostwell-knownOpenSourceinitiative,thereisanotherprojectthatcontributedenormouslytothepopularityoftheLinuxoperatingsystem.ThisprojectiscalledSAMBA,anditsachievementisthereverseengineeringoftheServerMessageBlock（SMB）/CommonInternetFileSystem（CIFS）protocolusedforfile-andprint-servingonPC-relatedmachines,nativelysupportedbyMSWindowsNTandOS/2,andLinux.PackagesarenowavailableforalmosteverysystemandprovideinterconnectionsolutionsinmixedenvironmentsusingMSWindowsprotocols:

Windows-compatible（uptoandincludingWin2K）file-andprint-servers.

MaybeevenmoresuccessfulthantheSAMBAprojectistheApacheHTTPserver