File attributes and operations in Operating Systems - Cheat Sheet & Quick Revision

Recall & Review

beginner

What are file attributes in an operating system?

File attributes are metadata that describe properties of a file, such as its size, creation date, permissions, and type. They help the system manage and control access to files.

beginner

Name three common file operations performed by an operating system.

Common file operations include:

• Creating a file
• Reading from a file
• Writing to a file
• Deleting a file
• Renaming a file

beginner

What does the read-only attribute mean for a file?

A read-only attribute means the file can be opened and read, but it cannot be modified or deleted until the attribute is changed.

intermediate

How does the hidden attribute affect a file?

The hidden attribute makes a file invisible in normal directory listings, helping to protect system or important files from accidental changes.

intermediate

Explain the difference between sequential and random access file operations.

Sequential access reads or writes data in order, from start to end. Random access allows jumping directly to any part of the file to read or write data, making it faster for certain tasks.

Which file attribute prevents a file from being modified?

A Read-only

B Hidden

C Archive

D System

The read-only attribute stops any changes to the file until the attribute is removed.

What operation would you use to remove a file from the system?

A Copy

B Rename

C Delete

D Open

Deleting a file removes it from the storage and directory listings.

Which file attribute makes a file invisible in normal folder views?

A Hidden

B Read-only

C Executable

D Temporary

The hidden attribute hides the file from standard directory listings.

What is the main difference between sequential and random access?

A Random access only reads files; sequential access only writes files.

B Sequential access reads data in order; random access jumps to any part.

C Sequential access is faster than random access.

D They are the same.

Sequential access processes data in order, while random access allows direct jumps to any location.

Which file operation changes the name of a file?

A Copy

B Delete

C Move

D Rename

Renaming changes the file's name without altering its content.

Describe what file attributes are and why they are important in managing files.

Think about the extra information that tells the system how to treat a file.

Explain the difference between sequential and random access file operations with examples.

Consider how you read a book from start to finish versus jumping to a chapter.

Practice

1. Which of the following is NOT a common file attribute in operating systems?

easy

A. File color

B. File size

C. Creation date

D. File permissions

Solution

1. Step 1: Understand common file attributes

   Common file attributes include size, creation date, and permissions which describe the file's properties.

2. Step 2: Identify the incorrect attribute

   File color is not a standard attribute tracked by operating systems; it is usually a display feature in some file managers.

3. Final Answer:

   File color -> Option A

4. Quick Check:

   File color is not a file attribute [OK]

Hint: File attributes describe file details, not display colors [OK]

Common Mistakes:

• Confusing display features with file attributes
• Thinking file color is stored as metadata

2. Which command is used to change file permissions in Unix-like systems?

easy

A. ls

B. chown

C. chmod

D. rm

Solution

1. Step 1: Recall commands related to file permissions

   chmod is the command used to change file permissions, allowing read, write, and execute rights to be set.

2. Step 2: Differentiate from other commands

   chown changes file ownership, ls lists files, and rm deletes files, so they do not change permissions.

3. Final Answer:

   chmod -> Option C

4. Quick Check:

   chmod changes permissions [OK]

Hint: chmod = change mode (permissions) [OK]

Common Mistakes:

• Confusing chmod with chown
• Using ls or rm for permissions

3. Consider this Python code snippet that reads a file's size:

import os
file_path = 'example.txt'
size = os.path.getsize(file_path)
print(size)

What does this code output?

medium

A. The number of lines in the file

B. The size of the file in bytes

C. The file's creation date

D. The file's permissions

Solution

1. Step 1: Understand os.path.getsize function

   This function returns the size of the file in bytes, not lines or dates.

2. Step 2: Analyze the print output

   Printing the size variable outputs the file size in bytes as an integer.

3. Final Answer:

   The size of the file in bytes -> Option B

4. Quick Check:

   os.path.getsize returns file size [OK]

Hint: getsize returns bytes, not lines or dates [OK]

Common Mistakes:

• Thinking it counts lines
• Confusing size with creation date

4. What is wrong with this command to rename a file in Linux?

mv file1.txt file2.txt/

medium

A. The trailing slash after file2.txt treats it as a directory

B. It will delete file1.txt instead of renaming

C. The command syntax is incorrect; mv needs -r option

D. It will copy file1.txt instead of renaming

Solution

1. Step 1: Understand mv command syntax

   mv renames or moves files. The destination should be a file name or directory.

2. Step 2: Analyze the trailing slash effect

   A trailing slash after file2.txt makes the system treat it as a directory, which likely does not exist, causing an error.

3. Final Answer:

   The trailing slash after file2.txt treats it as a directory -> Option A

4. Quick Check:

   Trailing slash means directory [OK]

Hint: Trailing slash means directory, not file [OK]

Common Mistakes:

• Thinking mv deletes files
• Assuming mv copies files
• Believing -r is needed for mv

5. You want to create a script that lists all files in a folder but only shows files larger than 1MB. Which approach correctly uses file attributes and operations?

hard

A. Change permissions of files larger than 1MB before listing

B. List all files and print their names without checking size

C. Delete files smaller than 1MB and then list remaining files

D. List all files, then check each file's size attribute and print only those >1MB

Solution

1. Step 1: Understand the requirement

   The task is to list files filtered by size, so size attribute must be checked.

2. Step 2: Evaluate each option

   List all files, then check each file's size attribute and print only those >1MB correctly filters files by size before printing. List all files and print their names without checking size ignores size. Delete files smaller than 1MB and then list remaining files deletes files, which is unsafe. Change permissions of files larger than 1MB before listing changes permissions unnecessarily.

3. Final Answer:

   List all files, then check each file's size attribute and print only those >1MB -> Option D

4. Quick Check:

   Filter by size attribute before listing [OK]

Hint: Filter files by size attribute before listing [OK]

Common Mistakes:

• Ignoring file size attribute
• Deleting files instead of filtering
• Changing permissions unnecessarily