Quick Answer
The correct command is `chmod o+r file`. This works because the file’s 640 permission set grants read/write to the owner (root) and read to the group (root), but provides no access for others. Since the user is neither root nor a member of the root group, they fall into the “others” category, and adding the read permission for others with `o+r` directly resolves the issue without altering ownership or group membership. On the CompTIA Linux+ XK0-005 exam, this scenario tests your understanding of Linux file permission categories—owner, group, and others—and how the `chmod` command modifies them using symbolic notation. A common trap is assuming the user can be added to the root group, but that would grant unnecessary privileges; the simplest and most secure fix is to adjust only the others permission. To remember, think “o+r = others can read,” and note that 640 means “owner read/write, group read, others nothing”—so adding `o+r` changes it to 644.
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 access a file. The file has permissions 640 and is owned by root:root. The user is not root and not in the root group. Which command should the administrator use to allow the user to read the file?
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 o+r file
Correct: Adds read permission for others.
chgrp user file
Why wrong: Changes group, but user may not be in that group.
setfacl -m u:user:r file
Why wrong: Works but is more complex than needed.
chown user file
Why wrong: Changes ownership to user, but does not grant read to others.
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 o+r file
The file has permissions 640, which means the owner (root) has read/write, the group (root) has read, and others have no permissions. Since the user is not root and not in the root group, they fall into the 'others' category. The command `chmod o+r file` adds read permission for others, allowing the user to read the file without changing ownership or group membership.
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 o+r file
Why this is correct
Correct: Adds read permission for others.
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.
chgrp user file
Why it's wrong here
Changes group, but user may not be in that group.
setfacl -m u:user:r file
Why it's wrong here
Works but is more complex than needed.
chown user file
Why it's wrong here
Changes ownership to user, but does not grant read to others.
Common exam traps
The trap here is that candidates may overcomplicate the solution by choosing `setfacl` or `chown` when a simple `chmod` on the 'others' class is the correct and most efficient fix for a user who is neither the owner nor a group member.
Detailed technical explanation
The Unix permission model uses three triads (owner, group, others) with bits for read (4), write (2), and execute (1). The `chmod o+r` command adds the read bit (4) to the 'others' triad, effectively changing the permissions from 640 to 644. In a real-world scenario, using ACLs with `setfacl` is more granular and often preferred in multi-user environments, but the XK0-005 exam emphasizes understanding of basic permission commands.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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
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 o+r file — The file has permissions 640, which means the owner (root) has read/write, the group (root) has read, and others have no permissions. Since the user is not root and not in the root group, they fall into the 'others' category. The command `chmod o+r file` adds read permission for others, allowing the user to read the file without changing ownership or group membership.
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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