- A
groupadd projectx; usermod -G projectx bob carol; chmod 2770 /projectx
Why wrong: Invalid syntax for usermod; also -G without -a replaces groups.
- B
addgroup projectx; adduser bob projectx; adduser carol projectx; chmod u+s /projectx
Why wrong: adduser/addgroup are distribution-specific; chmod u+s sets setuid, not setgid.
- C
groupadd projectx; usermod -aG projectx bob; usermod -aG projectx carol; chmod g+s /projectx
Correct commands to add to group and set setgid.
- D
groupadd projectx; usermod -G projectx bob; usermod -G projectx carol; chmod g+s /projectx
Why wrong: This replaces all groups for each user.
Question 456 of 513
LFCS User and Group Management Practice Question
This LFCS practice question tests your understanding of user and group management. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A system administrator needs to create a shared group 'projectx' and add existing users 'bob' and 'carol' to it. The users need to collaborate on files in a directory /projectx. What is the correct sequence of commands to set up the group and ensure new files created in /projectx are automatically owned by the group 'projectx'?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
groupadd projectx; usermod -aG projectx bob; usermod -aG projectx carol; chmod g+s /projectx
Option C is correct because it uses `groupadd` to create the group, `usermod -aG` to append users to the group without removing them from other groups, and `chmod g+s` to set the setgid bit on the directory. The setgid bit ensures that new files created in /projectx inherit the group ownership of the directory (projectx), enabling collaboration.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
groupadd projectx; usermod -G projectx bob carol; chmod 2770 /projectx
Why it's wrong here
Invalid syntax for usermod; also -G without -a replaces groups.
- ✗
addgroup projectx; adduser bob projectx; adduser carol projectx; chmod u+s /projectx
Why it's wrong here
adduser/addgroup are distribution-specific; chmod u+s sets setuid, not setgid.
- ✓
groupadd projectx; usermod -aG projectx bob; usermod -aG projectx carol; chmod g+s /projectx
Why this is correct
Correct commands to add to group and set setgid.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
groupadd projectx; usermod -G projectx bob; usermod -G projectx carol; chmod g+s /projectx
Why it's wrong here
This replaces all groups for each user.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that `usermod -G` without `-a` overwrites the user's supplementary groups, and candidates often forget the `-a` flag, leading to accidental removal of existing group memberships.
Detailed technical explanation
How to think about this question
The setgid bit (mode 2xxx or `g+s`) on a directory causes the kernel to assign the directory's group to any newly created file or subdirectory, overriding the creator's primary group. This behavior is defined in POSIX and is essential for shared workspace setups. Without `-a` in `usermod`, the `-G` option resets the supplementary group list, which is a common pitfall when managing group memberships.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the LFCS exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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FAQ
Questions learners often ask
What does this LFCS question test?
User and Group Management — This question tests User and Group Management — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: groupadd projectx; usermod -aG projectx bob; usermod -aG projectx carol; chmod g+s /projectx — Option C is correct because it uses `groupadd` to create the group, `usermod -aG` to append users to the group without removing them from other groups, and `chmod g+s` to set the setgid bit on the directory. The setgid bit ensures that new files created in /projectx inherit the group ownership of the directory (projectx), enabling collaboration.
What should I do if I get this LFCS question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jul 4, 2026
This LFCS practice question is part of Courseiva's free Linux Foundation certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the LFCS exam.
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