Quick Answer
The answer is `chmod 770 /directory`. This command is correct because the directory’s current permissions of 755 grant the owner read, write, and execute (7), but the group only has read and execute (5), which blocks group members from writing. Since the user belongs to the group but is not the owner, adding group write permission requires setting the group permission to 7, resulting in 770 (owner rwx, group rwx, others none). On the CompTIA Linux+ XK0-005 exam, this scenario tests your understanding of Linux file permissions and the `chmod` command, often appearing as a performance-based item where you must identify the exact octal mode that resolves a group write restriction. A common trap is confusing the group permission digit with the owner digit or forgetting that execute permission is needed to access a directory. Memory tip: think “770 for group go” — the middle 7 gives the group the same full access as the owner, while the trailing 0 locks out others.
This XK0-005 practice question tests your understanding of troubleshooting. 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 cannot write to a directory that has permissions 755. The user is not the owner but belongs to the group. Which command would allow the user to write?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "which command"
Why it matters: Tests specific CLI syntax. Recall the exact command and its required context — near-synonyms and partial matches are common distractors.
chmod 770 /directory
770 adds write permission for the group, allowing the user to write.
chmod 755 /directory
Why wrong: 755 is the current permission; no change.
chmod 777 /directory
Why wrong: 777 gives write to everyone, including others, which is overly permissive and a security risk.
chmod 700 /directory
Why wrong: 700 removes all permissions for group and others, making it worse.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
chmod 770 /directory
The directory currently has permissions 755, meaning the owner has rwx (7), the group has r-x (5), and others have r-x (5). Since the user belongs to the group but is not the owner, they need group write permission. The chmod 770 command sets the group permission to rwx (7), granting the user write access while preserving owner and group ownership semantics.
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.
chmod 770 /directory
Why this is correct
770 adds write permission for the group, allowing the user to write.
Clue confirmation
The clue word "which command" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
chmod 755 /directory
Why it's wrong here
755 is the current permission; no change.
chmod 777 /directory
Why it's wrong here
777 gives write to everyone, including others, which is overly permissive and a security risk.
chmod 700 /directory
Why it's wrong here
700 removes all permissions for group and others, making it worse.
Common exam traps
The trap here is that candidates may choose chmod 777 thinking it is the only way to grant write access, overlooking that the user is already in the group and only group write permission is needed.
Detailed technical explanation
Linux file permissions are stored as a 12-bit value: three bits for setuid, setgid, and sticky, plus nine bits for owner/group/other permissions. The octal notation (e.g., 755) directly maps to these bits: 7 = rwx (111 binary), 5 = r-x (101 binary). The chmod command modifies the inode's permission field; group membership is checked at access time by the kernel's VFS layer, which compares the user's GID against the file's group GID. A real-world scenario is a shared project directory where team members need to collaborate; using 770 ensures only the group can write, preventing unauthorized changes by others.
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 XK0-005 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.
Troubleshooting — study guide chapter
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FAQ
Troubleshooting — This question tests Troubleshooting — Read the scenario before looking for a memorised answer..
The correct answer is: chmod 770 /directory — The directory currently has permissions 755, meaning the owner has rwx (7), the group has r-x (5), and others have r-x (5). Since the user belongs to the group but is not the owner, they need group write permission. The chmod 770 command sets the group permission to rwx (7), granting the user write access while preserving owner and group ownership semantics.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Yes — watch for: "which command". Tests specific CLI syntax. Recall the exact command and its required context — near-synonyms and partial matches are common distractors.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 25, 2026
This XK0-005 practice question is part of Courseiva's free CompTIA 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 XK0-005 exam.
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