Quick Answer
The answer is that chmod 755 sets file permissions to rwxr-xr-x. This octal value breaks down as 7 (4+2+1) for the owner, granting read, write, and execute, while the 5 (4+1) for both group and others gives only read and execute. This configuration is correct because it allows the owner full control to modify the file, while preventing non-owners from writing to it—a standard security practice for executable scripts and directories. On the Linux Foundation Certified System Administrator LFCS exam, this command tests your understanding of octal permission notation and the principle of least privilege; a common trap is confusing the 5 (read+execute) with 4 (read-only) or 6 (read+write). Remember the mnemonic: 7 is the owner’s full set, and 5 is the “safe execute” for everyone else—like a 5-star rating for read and execute only.
This LFCS practice question tests your understanding of essential commands. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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.
What is the purpose of the chmod 755 command in this exhibit?
Add execute permission for the owner only
Why wrong: 755 adds execute for all, not just owner.
Remove write permission for others
Why wrong: Others already had read-only; 755 does not remove write because they had none.
Set the setuid bit
Why wrong: chmod 755 does not set setuid; that would be 4755.
Set permissions to rwxr-xr-x
755 corresponds to rwxr-xr-x.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Set permissions to rwxr-xr-x
The chmod 755 command sets the file permissions to rwxr-xr-x, meaning the owner has read, write, and execute permissions (7), while the group and others have read and execute permissions (5). This is a common permission set for executable scripts and directories to allow execution without granting write access to non-owners.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Add execute permission for the owner only
Why it's wrong here
755 adds execute for all, not just owner.
Remove write permission for others
Why it's wrong here
Others already had read-only; 755 does not remove write because they had none.
Set the setuid bit
Why it's wrong here
chmod 755 does not set setuid; that would be 4755.
Set permissions to rwxr-xr-x
Why this is correct
755 corresponds to rwxr-xr-x.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
The trap here is that candidates often confuse the octal value 755 with adding execute only for the owner (option A) or think it removes write for others (option B), when in fact 755 sets a specific permission mask that includes execute for all and write only for the owner.
Detailed technical explanation
The octal value 755 breaks down as owner=7 (rwx), group=5 (r-x), others=5 (r-x). In Linux, the execute permission on a directory allows traversal (accessing files within), so 755 is standard for web server directories like /var/www/html to allow users to list and access content without modifying files. A subtle behavior: if a file has 755 but is not executable (e.g., a text file), the execute bits are ignored, but the permissions still show as rwxr-xr-x.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Essential Commands — study guide chapter
Learn the concepts, then practise the questions
Essential Commands practice questions
Targeted practice on this topic area only
All LFCS questions
513 questions across all exam domains
Linux Foundation Certified System Administrator LFCS study guide
Full concept coverage aligned to exam objectives
LFCS practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Practise LFCS questions linked to User and Group Management.
Practise LFCS questions linked to Operation of Running Systems.
Practise LFCS questions linked to Essential Commands.
Practise LFCS questions linked to Networking.
Practise LFCS questions linked to Service Configuration.
Practise LFCS questions linked to Storage Management.
Practise LFCS questions linked to LFCS fundamentals.
Practise LFCS questions linked to LFCS scenario.
Practise LFCS questions linked to LFCS troubleshooting.
Practice this exam
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Essential Commands — This question tests Essential Commands — Read the scenario before looking for a memorised answer..
The correct answer is: Set permissions to rwxr-xr-x — The chmod 755 command sets the file permissions to rwxr-xr-x, meaning the owner has read, write, and execute permissions (7), while the group and others have read and execute permissions (5). This is a common permission set for executable scripts and directories to allow execution without granting write access to non-owners.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Same concept, more angles
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 user wants to set the permissions of a file to 'rwxr-xr--'. Which octal permission value should they use with chmod?
easyWhy A: The permissions 'rwxr-xr--' correspond to owner: rwx (7), group: r-x (5), others: r-- (4). The octal value 754 is derived by summing the binary bits for each triad: read (4), write (2), execute (1). Thus, chmod 754 sets the exact permissions requested.
Last reviewed: Jun 11, 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.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.