whoami and id commands in Linux CLI - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

Output of whoami command

What is the output of the whoami command when run by a logged-in user named alice?

Linux CLI

whoami

A id

B alice

C users

D root

💡 Hint

The whoami command shows the current user's login name.

The whoami command prints the username of the current user running the command. If the user is 'alice', it outputs 'alice'.

💻 Command Output

intermediate

Understanding id command output

What does the id command output show when run by user bob with UID 1001, GID 1001, and groups 1001 and 27?

Linux CLI

id

A user=bob uid=1001 gid=1001 groups=1001,27

B bob 1001 1001 27

C uid=1001(bob) gid=1001(bob) groups=1001(bob),27(sudo)

D uid=bob gid=1001 groups=27

💡 Hint

The id command shows user ID, group ID, and group memberships with names.

The id command outputs the user ID (uid), group ID (gid), and all groups the user belongs to, showing both numeric IDs and names.

🧠 Conceptual

advanced

Difference between whoami and id commands

Which statement correctly describes the difference between whoami and id commands?

A <code>whoami</code> shows only the current username; <code>id</code> shows user and group IDs and group memberships.

B <code>whoami</code> shows user and group IDs; <code>id</code> shows only the username.

C <code>whoami</code> shows all logged-in users; <code>id</code> shows current user only.

D <code>whoami</code> shows group memberships; <code>id</code> shows the current username.

💡 Hint

Think about what each command prints about the user.

whoami prints the username of the current user. id prints detailed info: user ID, group ID, and all groups the user belongs to.

💻 Command Output

advanced

Output of id command with multiple groups

What is the output of id for user carol with UID 2000, GID 3000, and groups 3000, 4, and 27, where group 4 is 'adm' and 27 is 'sudo'?

Linux CLI

id

A uid=carol gid=3000 groups=4,27

B uid=2000 gid=3000 groups=carol,adm,sudo

C carol 2000 3000 4 27

D uid=2000(carol) gid=3000(carol) groups=3000(carol),4(adm),27(sudo)

💡 Hint

The id command shows numeric IDs and group names.

The output format includes numeric IDs and names for user ID, group ID, and all groups the user belongs to.

💻 Command Output

expert

Error when running id with invalid option

What error message appears when running id --unknown on a Linux system?

Linux CLI

id --unknown

A

id: unrecognized option '--unknown'
Try 'id --help' for more information.

B id: invalid argument '--unknown'

C bash: id: command not found

D id: option requires an argument -- 'unknown'

💡 Hint

Invalid options usually produce a message about unrecognized option.

The id command prints an error message about unrecognized option and suggests using --help.