This LFCS practice question tests your understanding of essential commands. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 user reports that they cannot delete a file named 'important.txt' located in their home directory. The file is owned by the user and the user has write permission on the directory. Running 'rm important.txt' produces the error: 'rm: cannot remove 'important.txt': Operation not permitted'. The user has also tried using 'sudo rm' but gets the same error. Which of the following is the most likely cause and correct solution?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The file has the immutable attribute set. Use 'lsattr important.txt' and if the 'i' attribute is present, remove it with 'chattr -i important.txt'.
The error 'Operation not permitted' despite the user owning the file and having write permission on the directory indicates a filesystem-level restriction rather than a permission or ACL issue. The immutable attribute (i) on the file prevents any modification, including deletion, even by the root user. Running 'lsattr' reveals the attribute, and 'chattr -i' removes it, allowing deletion.
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.
✗
The file has an ACL that denies deletion. Use 'setfacl -b important.txt' to remove ACLs.
Why it's wrong here
ACLs do not cause 'Operation not permitted' for root.
✓
The file has the immutable attribute set. Use 'lsattr important.txt' and if the 'i' attribute is present, remove it with 'chattr -i important.txt'.
Why this is correct
The immutable attribute prevents deletion; removing it allows deletion.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The file is currently in use by another process. Use 'lsof' to find the process and kill it.
Why it's wrong here
An open file causes 'device or resource busy', not 'Operation not permitted'.
✗
The directory has the sticky bit set, preventing deletion. Use 'chmod o-t .' to remove the sticky bit.
Why it's wrong here
The sticky bit prevents deletion of other users' files, but the user owns this file.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse 'Operation not permitted' with standard permission errors, overlooking the immutable attribute as a filesystem-level override that affects even root and is not visible with 'ls -l'.
Detailed technical explanation
How to think about this question
The immutable attribute (i) is a Linux filesystem flag stored in the inode, enforced by the VFS layer; it overrides all permission checks, including root, making the file completely immutable until the flag is cleared. This attribute is commonly used for security hardening (e.g., preventing modification of critical system files) and can be set or removed only by the root user or a user with CAP_LINUX_IMMUTABLE capability. In real-world scenarios, malware or accidental 'chattr +i' can lock user files, requiring 'lsattr' and 'chattr -i' to recover.
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.
Essential Commands — This question tests Essential Commands — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The file has the immutable attribute set. Use 'lsattr important.txt' and if the 'i' attribute is present, remove it with 'chattr -i important.txt'. — The error 'Operation not permitted' despite the user owning the file and having write permission on the directory indicates a filesystem-level restriction rather than a permission or ACL issue. The immutable attribute (i) on the file prevents any modification, including deletion, even by the root user. Running 'lsattr' reveals the attribute, and 'chattr -i' removes it, allowing deletion.
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.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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