TAILIEUCHUNG - Lecture Operating system concepts - Chapter 11: File-system interface

In this chapter, we consider the various aspects of files and the major directory structures. We also discuss the semantics of sharing files among multiple processes, users, and computers. Finally, we discuss ways to handle file protection, necessary when we have multiple users and we want to control who may access files and how files may be accessed. | Chapter 11: File-System Interface I File Concept I Access Methods I Directory Structure I File System Mounting I File Sharing I Protection Operating System Concepts Silberschatz, Galvin and Gagne 2002 File Concept I Contiguous logical address space I Types: ✦ Data ✔ numeric ✔ character ✔ binary ✦ Program Operating System Concepts Silberschatz, Galvin and Gagne 2002 File Structure I None - sequence of words, bytes I Simple record structure ✦ Lines ✦ Fixed length ✦ Variable length I Complex Structures ✦ Formatted document ✦ Relocatable load file I Can simulate last two with first method by inserting appropriate control characters. I Who decides: ✦ Operating system ✦ Program Operating System Concepts Silberschatz, Galvin and Gagne 2002 File Attributes I Name – only information kept in human-readable form. I Type – needed for systems that support different types. I Location – pointer to file location on device. I Size – current file size. I Protection – controls who can do reading, writing, executing. I Time, date, and user identification – data for protection, security, and usage monitoring. I Information about files are kept in the directory structure, which is maintained on the disk. Operating System Concepts Silberschatz, Galvin and Gagne 2002 File Operations I Create I Write I Read I Reposition within file – file seek I Delete I Truncate I Open(Fi) – search the directory structure on disk for entry Fi, and move the content of entry to memory. I Close (Fi) – move the content of entry Fi in memory to directory structure on disk. Operating System Concepts Silberschatz, Galvin and Gagne 2002 File Types – Name, Extension Operating System Concepts Silberschatz, Galvin and Gagne 2002 Access Methods I Sequential Access read next write next reset no read after last write (rewrite) I Direct Access read n write n position to n read next write next rewrite n n = relative block number Operating System .

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• Operating system concepts
• Lecture Operating system concepts
• Operating system
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