OS Directory Operations: Quiz and Flashcards

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Questions and Answers

What is one of the advantages of a logically organized directory?

To locate a file slowly

To group files by alphabetical order

To ensure all files have unique names

To locate a file quickly (correct)

What is a limitation of a single-level directory?

It causes naming and grouping problems (correct)

It allows for multiple users to have the same name for different files

It allows for convenient naming of files

It allows for grouping of files by properties

What is a characteristic of a two-level directory?

Separate directories for each file type

A single directory for each file property

Separate directory for each user (correct)

A single directory for all users

What is an advantage of a two-level directory over a single-level directory?

It solves the naming problem Signup and view all the answers

What is a benefit of allowing multiple names for the same file?

It allows for convenient naming of files Signup and view all the answers

What is a fundamental requirement for any application program?

To include its own code to interpret an input file as to the appropriate structure Signup and view all the answers

What is the purpose of open file locking in operating systems?

To control access to files shared among multiple processes Signup and view all the answers

What is the unit of disk I/O performed by the operating system?

One block (physical record) Signup and view all the answers

What is the similarity between shared lock and reader lock?

Both allow multiple processes to read from the file Signup and view all the answers

What is a common solution to the problem of logical records varying in length?

Packing a number of logical records into physical blocks Signup and view all the answers

What is the primary difference between sequential-access and direct-access files?

The way the file is accessed Signup and view all the answers

What is the main advantage of supporting a minimal number of file structures in an operating system?

It provides maximum flexibility for applications Signup and view all the answers

What is the main drawback of supporting multiple file structures in an operating system?

It increases the size of the operating system Signup and view all the answers

What is the purpose of a directory structure in a file system?

To provide a collection of nodes containing information about all files Signup and view all the answers

What is the primary purpose of file types and extensions in an operating system?

To indicate the internal structure of a file Signup and view all the answers

What is the term for a disk or partition that is used without a file system?

Raw disk Signup and view all the answers

What is the main advantage of a single file structure in an operating system?

It simplifies the operating system design Signup and view all the answers

What is the term for a entity containing a file system?

Volume Signup and view all the answers

What is the primary function of a file system in terms of searching for a file?

To implement search algorithms to locate the file Signup and view all the answers

What is the consequence of deleting a file in a file system?

The storage space occupied by the file is marked as available for reuse Signup and view all the answers

What is the term for navigating through directories and subdirectories to locate files or perform operations on them?

Traversing the file system Signup and view all the answers

Study Notes

File Structure

Each application program must include its own code to interpret an input file as to the appropriate structure.
The OS must support at least one structure, that of executable files, to load and run programs.

Internal File Structure

All disk I/O is performed in units of one block (physical record), and all blocks are the same size.
Logical records within a file may vary in length.
Packing a number of logical records into physical blocks is a common solution to this problem.
The packing can be done either by the user's application program or by the operating system.

Access Methods

Sequential Access:
- Read next
- Write next
- Reset
- No read after last write (rewrite)
Direct Access:
- File is fixed length logical records
- Read n (n is the block number)
- Write n
- Position to n
- Read next
- Write next
- Rewrite n
Relative block numbers allow the OS to decide where the file should be placed.

Directory Structure

A collection of nodes containing information about all files.
Directory files reside on disk.
Directory structure is organized logically to obtain:
- Efficiency: locating a file quickly
- Naming: convenient to users
- Grouping: logical grouping of files by properties

Operations Performed on Directory

Search for a file: The file system typically implements search algorithms to locate the file based on its name, attributes, or metadata.
Create a file: The file system creates an entry in the directory structure containing the file's name and location, along with any necessary metadata.
Delete a file: The file system marks the storage space occupied by the file as available for reuse.
List a directory: The file system provides commands or APIs to enumerate the contents of a directory.
Rename a file: The file system updates the directory entry associated with the file to reflect the new name.
Traverse the file system: Traversing the file system involves navigating through directories and subdirectories to locate files or perform operations on them.

Directory Organization

Single-Level Directory:
- A single directory for all users
- Naming problem
- Grouping problem
Two-Level Directory:
- Separate directory for each user
- Each user has their own user file directory (UFD)

Open File Locking

Provided by some operating systems and file systems to control access to files shared among multiple processes.
Similar to reader-writer locks.
Shared lock: several processes can acquire concurrently.
Exclusive lock: only one process at a time can acquire such a lock.

File Types

File types can be used to indicate the internal structure of the file that dictates how the data is stored, accessed, and interpreted.
Single File Structure: files are a sequence of words, bytes.
Multiple File Structures:
- The OS supports multiple file structures, making the size of the operating system cumbersome.
- Another approach is for the OS to support a minimal number of file structures, providing maximum flexibility but little support.

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Description

This quiz covers the logical organization of directories in Operating Systems, including efficiency, naming, and grouping of files. It explores how different users can have the same file names and how files can have multiple names. The quiz is based on the 9th Edition of Operating System Concepts by Silberschatz, Galvin, and Gagne.