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1 Pertemuan 21 Sistem File Matakuliah: T0316/sistem Operasi Tahun: 2005 Versi/Revisi: 5
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2 Learning Outcomes Pada akhir pertemuan ini, diharapkan mahasiswa akan mampu : menjelaskan konsep sistem file (C2)
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3 Outline Materi Penamaan file Struktur file Tipe File Pengaksesan file Operasi file Direktori
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4 Long-term Information Storage 1.Must store large amounts of data 2.Information stored must survive the termination of the process using it 3.Multiple processes must be able to access the information concurrently
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5 File Naming Typical file extensions
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6 File Structure Three kinds of files –byte sequence –record sequence –tree
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7 File Types Regular file ASCII/binary Directories Character special file Block special file
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8 File Types (binary files) (a) An executable file (b) An archive Header Text Data Relocation bits Symbol table Collection of library procedures (modules) compiled but not linked
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9 File Access Sequential access –read all bytes/records from the beginning –cannot jump around, could rewind or back up –convenient when medium was mag tape Random access –bytes/records read in any order –essential for data base systems –read can be … move file marker (seek), then read or … read and then move file marker
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10 File Attributes Possible file attributes
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11 File Operations 1.Create 2.Delete 3.Open 4.Close 5.Read 6.Write 7.Append 8.Seek 9.Get attributes 10.Set Attributes 11.Rename
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12 An Example Program Using File System Calls (1/2) Eg. copyfile abc xyz
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13 An Example Program Using File System Calls (2/2)
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14 Memory-Mapped Files (a) Segmented process before mapping files into its address space (b) Process after mapping existing file abc into one segment creating new segment for xyz + eliminates I/O – hard to know exact length of output files, consistency for shared files, file may larger than segment
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15 Directories Single-Level Directory Systems A single level directory system –contains 4 files –owned by 3 different people, A, B, and C
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16 Two-level Directory Systems Letters indicate owners of the directories and files
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17 Hierarchical Directory Systems A hierarchical directory system
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18 A UNIX directory tree Path Names Absolute vs relative path name
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19 Directory Operations 1.Create 2.Delete 3.Opendir 4.Closedir 5.Readdir 6.Rename 7.Link 8.Unlink
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