User accounts and permissions in Intro to Computing - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a new user account named 'alice'.

Intro to Computing

create_user [1]

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

Aalice

Bbob

Cadmin

Dguest

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different username than 'alice'.

Confusing user roles with usernames.

The command create_user alice creates a new user account named 'alice'.

2fill in blank

medium

Complete the command to grant read permission to user 'alice' on file 'report.txt'.

Intro to Computing

grant_permission [1] report.txt read

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

Awrite

Badmin

Calice

Dguest

Attempts:

3 left

💡 Hint

Common Mistakes

Using permission types instead of usernames.

Confusing file names with user names.

The command grant_permission alice report.txt read gives user 'alice' read access to the file 'report.txt'.

3fill in blank

hard

Fix the error in the command to revoke write permission from user 'bob' on 'data.csv'.

Intro to Computing

revoke_permission [1] data.csv write

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

Adata.csv

Bbob

Cwrite

Dalice

Attempts:

3 left

💡 Hint

Common Mistakes

Using permission types or file names instead of the username.

Mixing up usernames.

The command revoke_permission bob data.csv write correctly revokes write permission from user 'bob' on the file 'data.csv'.

4fill in blank

hard

Fill both blanks to check if user 'carol' has execute permission on 'script.sh'.

Intro to Computing

check_permission [1] [2] execute

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

Acarol

Bread

Cscript.sh

Dwrite

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping the order of username and filename.

Using permission types instead of username or filename.

The command check_permission carol script.sh execute checks if user 'carol' has execute permission on the file 'script.sh'.

5fill in blank

hard

Fill both blanks to create a dictionary mapping users to their permission levels for 'project.doc'.

Intro to Computing

permissions = {: {BLANK_2}} for {{BLANK_2}} in users

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

Auser

Bpermissions[user]

Cusers

D{

Attempts:

3 left

💡 Hint

Common Mistakes

Missing the opening brace for the dictionary.

Using incorrect variable names.

Swapping keys and values.

The dictionary comprehension permissions = {user: permissions[user] for user in users} creates a mapping of each user to their permission level.

Practice

1. What is the main purpose of a user account on a computer?

easy

A. To increase the internet speed

B. To speed up the computer's processor

C. To identify who is using the computer

D. To install new software automatically

Solution

1. Step 1: Understand the role of user accounts

   User accounts are created to recognize and separate different users on the same computer.

2. Step 2: Identify the correct purpose

   Among the options, only identifying the user matches the main purpose of user accounts.

3. Final Answer:

   To identify who is using the computer -> Option C

4. Quick Check:

   User account = Identify user [OK]

Hint: User accounts are about who, not how fast [OK]

Common Mistakes:

• Confusing user accounts with hardware speed
• Thinking user accounts control internet speed
• Assuming user accounts install software automatically

2. Which of the following is the correct way to represent a permission that allows a user to read and write files?

easy

A. rwx

B. ---

C. r--

D. rw-

Solution

1. Step 1: Understand permission symbols

   In permissions, 'r' means read, 'w' means write, and 'x' means execute. A dash '-' means no permission.

2. Step 2: Match read and write permissions

   Read and write together are represented as 'rw-'. 'rwx' includes execute, which is not asked.

3. Final Answer:

   rw- -> Option D

4. Quick Check:

   Read + Write = rw- [OK]

Hint: r=read, w=write, x=execute; dash means no permission [OK]

Common Mistakes:

• Including execute permission when not needed
• Using only 'r' for read and write
• Confusing dashes with permission letters

3. Consider this scenario: A file has permissions set to r-- for a user. What can the user do with this file?

medium

A. Only read the file

B. Read and modify the file

C. Execute the file

D. Delete the file

Solution

1. Step 1: Interpret the permission string 'r--'

   'r' means read permission is granted; '-' means no write or execute permission.

2. Step 2: Determine allowed actions

   With only read permission, the user can open and view the file but cannot change or run it.

3. Final Answer:

   Only read the file -> Option A

4. Quick Check:

   r-- means read only [OK]

Hint: r-- means read only, no write or execute [OK]

Common Mistakes:

• Assuming write permission is included
• Thinking execute permission is granted
• Confusing delete with permissions shown

4. A user tries to edit a file but gets a 'Permission Denied' error. Which of the following is the most likely cause?

medium

A. The file is corrupted

B. The file has read-only permission for the user

C. The user is logged out

D. The computer is turned off

Solution

1. Step 1: Understand 'Permission Denied' meaning

   This error means the user lacks the rights to perform the action on the file.

2. Step 2: Identify permission issue cause

   If the file is read-only, the user cannot edit it, causing the error. Other options do not relate to permissions.

3. Final Answer:

   The file has read-only permission for the user -> Option B

4. Quick Check:

   Permission Denied = insufficient rights [OK]

Hint: Permission Denied usually means no write access [OK]

Common Mistakes:

• Blaming file corruption for permission errors
• Assuming user login status causes permission errors
• Confusing computer power state with permissions

5. An administrator wants to give a user permission to read and execute files but not modify them. Which permission string should be assigned?

hard

A. r-x

B. rwx

C. rw-

D. --x

Solution

1. Step 1: Understand required permissions

   The user needs read (r) and execute (x) permissions but no write (w) permission.

2. Step 2: Match permission string

   "r-x" means read and execute allowed, write denied. Other options either allow write or deny read.

3. Final Answer:

   r-x -> Option A

4. Quick Check:

   Read + Execute, no write = r-x [OK]

Hint: r-x means read and execute, no write [OK]

Common Mistakes:

• Choosing rwx which allows write
• Selecting rw- which lacks execute
• Picking --x which lacks read