File attributes and operations in Operating Systems - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to check if a file is readable.

Operating Systems

if os.access('example.txt', [1]):
    print('File is readable')

Drag options to blanks, or click blank then click option'

Aos.W_OK

Bos.R_OK

Cos.X_OK

Dos.F_OK

Attempts:

3 left

💡 Hint

Common Mistakes

Using write or execute flags instead of read flag.

The os.R_OK flag checks if the file is readable.

2fill in blank

medium

Complete the code to open a file for writing only if it exists.

Operating Systems

with open('data.txt', '[1]') as file:
    file.write('Hello')

Drag options to blanks, or click blank then click option'

Aw

Bx

Cr+

Da

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'w' which creates the file if it doesn't exist.

The mode r+ opens the file for reading and writing but fails if the file does not exist.

3fill in blank

hard

Fix the error in the code to get the size of a file in bytes.

Operating Systems

size = os.path.[1]('file.txt')
print(size)

Drag options to blanks, or click blank then click option'

Aget_size

Bfilesize

Csizeof

Dgetsize

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect function names like get_size or filesize.

The correct function to get file size is os.path.getsize.

4fill in blank

hard

Fill both blanks to create a dictionary of file names and their sizes for files larger than 1000 bytes.

Operating Systems

file_sizes = {f: os.path.[1](f) for f in files if os.path.[2](f) and os.path.getsize(f) > 1000}

Drag options to blanks, or click blank then click option'

Agetsize

Bexists

Disfile

Attempts:

3 left

💡 Hint

Common Mistakes

Using exists instead of isfile for file check.

Use getsize to get file size and isfile to ensure the path is a file.

5fill in blank

hard

Fill all three blanks to filter files by extension and size, then create a dictionary with uppercase file names and their sizes.

Operating Systems

filtered = {f.[1](): os.path.[2](f) for f in files if f.[3]('.txt') and os.path.getsize(f) > 500}

Drag options to blanks, or click blank then click option'

Aupper

Bgetsize

Cendswith

Dlower

Attempts:

3 left

💡 Hint

Common Mistakes

Using lower() instead of upper(), or wrong method for extension check.

Use upper() to convert file names, getsize to get file size, and endswith to filter by '.txt' extension.

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