This document discusses the key components of file systems and directories. It notes that there are three essential requirements for long-term information storage: a large storage capacity, survival of the termination of processes using the information, and concurrent access by multiple processes. It describes three types of file structures, ways to access files sequentially or randomly, common file operations, and how single-level, two-level, and hierarchical directory systems are organized.

1. Presented by
Anil Pokhrel
Bsccsit
3 semester
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2. Contents
 Three essential requirements for long-term
information storage
 File Structure
 File Types
 File Access
 File Operations
 Directories
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3. Three essential requirements for
long-term information storage
 It must be possible to store a very large amount of
information.
 The information must survive the termination of the
process using it.
 Multiple processes must be able to access the information
concurrently.
 Files are managed by the operating system; part of the
operating system dealing with files is known as the file
system.
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4. 4
File Structure
 Three kinds of files
 byte sequence
 record sequence
 tree

5. File Types
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6. 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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7. 7
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

8. 8
Directories
Single-Level Directory Systems
 A single level directory system
 contains 4 files
 owned by 3 different people, A, B, and C

9. 9
Two-level Directory Systems
Letters indicate owners of the directories and files

10. 10
Hierarchical Directory Systems
A hierarchical directory system

11. Refernce
 http://download.microsoft.com/download/9/6/D/96
D0705A-003A-4CE2-B2B2-
2A437635400C/MS%20vs%20%20Red%20Hat%20WP.
pdf
 http://smallbusiness.chron.com/five-common-
operating-systems-28217.html
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