ch11-file-system interface

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1、Chapter11:File-SystemInterfaceFileConceptAccessMethodsDirectoryStructureFileSystemMountingFileSharingProtectionOperatingSystemConceptsFileConceptContiguouslogicaladdressspaceTypes:DatanumericcharacterbinaryProgramOperatingSystemConceptsFileStructureNone-seq

2、uenceofwords,bytesSimplerecordstructureLinesFixedlengthVariablelengthComplexStructuresFormatteddocumentRelocatableloadfileCansimulatelasttwowithfirstmethodbyinsertingappropriatecontrolcharacters.Whodecides:OperatingsystemProgramOperatingSystemConceptsFileAt

3、tributesName–onlyinformationkeptinhuman-readableform.Type–neededforsystemsthatsupportdifferenttypes.Location–pointertofilelocationondevice.Size–currentfilesize.Protection–controlswhocandoreading,writing,executing.Time,date,anduseridentification–dataforprote

4、ction,security,andusagemonitoring.Informationaboutfilesarekeptinthedirectorystructure,whichismaintainedonthedisk.OperatingSystemConceptsFileOperationsCreateWriteReadRepositionwithinfile–fileseekDeleteTruncateOpen(Fi)–searchthedirectorystructureondiskforentr

5、yFi,andmovethecontentofentrytomemory.Close(Fi)–movethecontentofentryFiinmemorytodirectorystructureondisk.OperatingSystemConceptsFileTypes–Name,ExtensionOperatingSystemConceptsAccessMethodsSequentialAccessreadnextwritenextresetnoreadafterlastwrite(rewrite)Di

6、rectAccessreadnwritenpositiontonreadnextwritenextrewritenn=relativeblocknumberOperatingSystemConceptsSequential-accessFileOperatingSystemConceptsSimulationofSequentialAccessonaDirect-accessFileOperatingSystemConceptsExampleofIndexandRelativeFilesOperatingSy

7、stemConceptsDirectoryStructureAcollectionofnodescontaininginformationaboutallfiles.F1F2F3F4FnDirectoryFilesBoththedirectorystructureandthefilesresideondisk.Backupsofthesetwostructuresarekeptontapes.OperatingSystemConceptsATypicalFile-systemOrganizationOpera

8、tingSystemConceptsInformationinaDeviceDirectoryNameTypeAddressCurrentlengthMaximumlengthDatelastaccessed(forarchival)Datelastupdated(fordump)OwnerID(whopays)Protectioninformation(discusslater)Operating