Cse 331 Lecture Slides


(c) The support of primitives for manipulating files and directories



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Lecture 1 Introduction
Lecture 2 Processes

(c) The support of primitives for manipulating files and directories;

(d) The mapping of files onto disk storage;

(e) Backup of files on stable (non volatile) storage; and

(f) Protection and security of the files.

Protection

  • refers to a mechanism for controlling the access of programs, processes, or users to the resources defined by the computer together with some means of enforcement.
  • Protection can improve reliability by detecting latent errors at the interfaces between component subsystems.
  • An unprotected resource cannot defend against use (or misuse) by an unauthorised or incompetent user.

Command Interpretation

  • One of the most important components of an operating system is its command interpreter.
  • It is the primary interface between the user and the rest of the system.
  • This program is variously called:
    • The command line interpreter (CLI)
    • The shell (in Unix)

Summary

  • The Figure depicts the role of the operating system in coordinating all the functions.

OS Structure

  • We can view an OS from several vantage points i.e.
    • Services that the system provides
    • The interface that it makes available to users and programmers
    • Its components and their interconnections.

OS Structure Overview

Operating System Services

  • The common services provided by an OS are:
    • Program execution
    • I/O Operation
      • A program may require an I/O device while running
      • Therefore an OS must be able to provide the required I/O
    • File System Manipulation
      • Programs need to read or write files.
      • The OS gives permission to the program to operate on files.

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