whoami and id commands in Linux CLI - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to display the current logged-in username.

Linux CLI

[1]

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

Awhoami

Bid

Cpwd

Dls

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'id' instead of 'whoami' to get only the username.

Using 'pwd' which shows current directory, not username.

The whoami command shows the current logged-in username.

2fill in blank

medium

Complete the code to display the user ID and group ID of the current user.

Linux CLI

[1]

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

Agroups

Bwhoami

Cid

Dusers

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'whoami' which only shows username, not IDs.

Using 'groups' which shows only group names.

The id command shows user ID (UID), group ID (GID), and groups of the current user.

3fill in blank

hard

Fix the error in the command to show only the user ID number.

Linux CLI

id [1]

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

A-n

B-G

C-g

D-u

Attempts:

3 left

💡 Hint

Common Mistakes

Using '-g' which shows group ID instead of user ID.

Using '-n' which is for name, not numeric ID.

The -u option with id shows only the user ID number.

4fill in blank

hard

Fill both blanks to display the primary group name of the current user.

Linux CLI

id [1] [2]

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

A-n

B-g

C-G

D-u

Attempts:

3 left

💡 Hint

Common Mistakes

Using -G which shows all group IDs, not primary group.

Mixing up user ID options with group options.

Combining -n and -g shows only the primary group name.

5fill in blank

hard

Fill all three blanks to create a dictionary in Python showing username and user ID using shell commands.

Linux CLI

user_info = { [1]: "$(whoami)", [2]: "$(id [3])" }

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

A"username"

B"uid"

C-u

D"gid"

Attempts:

3 left

💡 Hint

Common Mistakes

Using "gid" instead of "uid" for user ID.

Forgetting quotes around dictionary keys.

This creates a Python dictionary with keys username and uid. The -u option gets the user ID number.

Practice

1. What does the whoami command display when run in a Linux terminal?

easy

A. The current logged-in username

B. The current directory path

C. The list of running processes

D. The system's IP address

Solution

1. Step 1: Understand the purpose of whoami

   The whoami command is designed to show the username of the current user logged into the shell.

2. Step 2: Compare with other options

   Options A, B, and C describe other commands or outputs unrelated to whoami.

3. Final Answer:

   The current logged-in username -> Option A

4. Quick Check:

   whoami = username [OK]

Hint: Remember: whoami = "Who am I?" shows your username [OK]

Common Mistakes:

• Confusing whoami with pwd (current directory)
• Thinking whoami shows system info
• Mixing up with commands showing processes

2. Which of the following is the correct syntax to display your user ID and group information in Linux?

easy

A. user id

B. id

C. whoami -u

D. showid

Solution

1. Step 1: Identify the correct command syntax

   The command id without arguments shows user ID, group ID, and group memberships.

2. Step 2: Check other options for validity

   Options A, B, and D are invalid commands or incorrect syntax for this purpose.

3. Final Answer:

   id -> Option B

4. Quick Check:

   id shows user and group info [OK]

Hint: Use simple id to see user and group IDs [OK]

Common Mistakes:

• Adding wrong flags to whoami
• Typing commands with spaces like 'user id'
• Using non-existent commands like showid

3. What will be the output of the command id -u if the current user has user ID 1001?

medium

A. 1001

B. uid=1001(user)

C. user=1001

D. id: invalid option

Solution

1. Step 1: Understand the -u option of id

   The -u option prints only the numeric user ID (UID) of the current user.

2. Step 2: Match output format

   The output will be just the number 1001, not a string with 'uid=' or other text.

3. Final Answer:

   1001 -> Option A

4. Quick Check:

   id -u = UID number only [OK]

Hint: id -u prints only your numeric user ID [OK]

Common Mistakes:

• Expecting full id output with -u
• Confusing uid= prefix with plain number
• Thinking -u is invalid option

4. You run the command id -u but get an error: "id: invalid option -- 'U'". What is the likely cause?

medium

A. You ran the command as root user

B. Your Linux system does not support the id command

C. You used a space between id and -u

D. You typed a capital U instead of lowercase u

Solution

1. Step 1: Check the option case sensitivity

   Linux commands are case sensitive. The option -u is lowercase. Using uppercase -U instead of lowercase -u can cause errors.

2. Step 2: Analyze the error message

   The error "invalid option -- 'U'" suggests the option letter was not recognized, likely due to uppercase letter typed instead of lowercase.

3. Final Answer:

   You typed a capital U instead of lowercase u -> Option D

4. Quick Check:

   Linux options are case sensitive [OK]

Hint: Check option letter case carefully; Linux is case sensitive [OK]

Common Mistakes:

• Typing uppercase instead of lowercase option
• Assuming id command is missing
• Adding spaces incorrectly in command

5. You want to write a script that prints your username and all group names you belong to. Which combination of commands will achieve this?

hard

A. id -un && id -G

B. whoami -g && id -u

C. echo $(whoami) && id -Gn

D. whoami && id -G

Solution

1. Step 1: Identify command to print username

   whoami prints the current username. Using echo $(whoami) prints it clearly.

2. Step 2: Identify command to print group names

   id -Gn prints all group names the user belongs to, separated by spaces.

3. Step 3: Evaluate options

   echo $(whoami) && id -Gn correctly combines username and group names. whoami -g && id -u uses invalid whoami -g. id -un && id -G uses id -un (which prints username) and id -G (which prints numeric group IDs, not names). whoami && id -G prints username and numeric group IDs, not names.

4. Final Answer:

   echo $(whoami) && id -Gn -> Option C

5. Quick Check:

   Use whoami + id -Gn for username and group names [OK]

Hint: Use whoami for username and id -Gn for group names [OK]

Common Mistakes:

• Using invalid flags with whoami
• Confusing numeric IDs with names
• Not combining commands properly