The correct answer is the command sequence `chown root:projectteam /project; chmod 2770 /project; setfacl -d -m o::---` because it establishes a shared directory with group inheritance and file ownership restrictions by combining the SGID bit with a default ACL. The SGID bit (represented by the 2 in 2770) ensures that any new files or subdirectories automatically inherit the group `projectteam`, while the 770 permissions grant full read, write, and execute access to the group but deny others. The default ACL `setfacl -d -m o::---` then strips all permissions for "other" users on newly created files, which enforces that only the file owner can modify their own files—group members can create and delete files but cannot edit each other’s work. On the LFCS exam, this scenario tests your understanding of how SGID and ACLs work together to solve real-world multi-user collaboration requirements; a common trap is forgetting that `chmod 2770` alone does not prevent group members from modifying each other’s files. Memory tip: think "SGID for group stickiness, default ACL for ownership lockiness."
LFCS User and Group Management Practice Question
This LFCS practice question tests your understanding of user and group management. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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.
An administrator needs to set up a shared directory /project for the group 'projectteam' (GID 5000). All members of the group should be able to create and delete files, but only the file owner can modify their own files. The directory should also ensure that new files inherit the group ownership. Which set of commands achieves this?
Option B is correct because it sets the SGID bit (2770) so new files inherit the group 'projectteam', grants rwx to the group, and uses a default ACL with `setfacl -d -m o::---` to remove 'other' permissions, ensuring only the file owner can modify their own files while group members can create/delete but not modify others' files.
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.
Sticky bit (1) prevents deletion; mask not inherited.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Linux Foundation often tests the distinction between SGID (2xxx) and sticky bit (1xxx), and candidates confuse them, thinking the sticky bit ensures group inheritance, or they overlook that removing 'other' permissions is necessary to prevent unauthorized access.
Detailed technical explanation
How to think about this question
The SGID bit (chmod 2xxx) on a directory causes new files and subdirectories to inherit the group ID of the directory, not the creating user's primary group, which is essential for shared project spaces. Default ACLs (`setfacl -d`) define permissions that are automatically applied to new files, and setting `o::---` ensures that 'others' have no access, while the group's rwx allows members to create/delete but not modify others' files due to the default file creation mask (umask) and the fact that only the file owner can change permissions or content without ACL overrides. In practice, this setup is common for collaborative directories where audit trails require owner accountability.
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 security administrator must allow nursing staff to reach a patient records server while blocking access from the guest Wi-Fi VLAN. After applying an extended ACL, traffic is still blocked from nursing workstations. The ACL was applied outbound instead of inbound on the wrong interface. Questions like this test ACL direction and placement rules.
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.
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: chown root:projectteam /project; chmod 2770 /project; setfacl -d -m o::--- /project — Option B is correct because it sets the SGID bit (2770) so new files inherit the group 'projectteam', grants rwx to the group, and uses a default ACL with `setfacl -d -m o::---` to remove 'other' permissions, ensuring only the file owner can modify their own files while group members can create/delete but not modify others' files.
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.
About these practice questions
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These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A system administrator needs to ensure that all users in the 'developers' group have read and write access to a shared project directory /project/data, but new files created in that directory should belong to the 'developers' group automatically. Which command sequence achieves this goal?
Why D: Option D is correct because `chown :developers /project/data` changes the group ownership of the directory to 'developers', and `chmod g+s /project/data` sets the setgid bit on the directory. The setgid bit ensures that new files created inside inherit the directory's group ('developers') instead of the creator's primary group, and the group ownership gives all members of 'developers' read and write access based on the directory's permissions (e.g., 775).
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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.
Question Discussion
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