The answer is that the service user 'myapp' lacks write permission to the log directory. This is because the directory /var/log/myapp/ has permissions 755, meaning the owner (root) has read, write, and execute; the group (root) has read and execute; and others have only read and execute. Since 'myapp' is not the owner and not in the root group, it falls into the 'others' category, which has no write bit set. Without write permission on the directory, the service cannot create or modify the log file /var/log/myapp.log, even if the file itself allows writing. On the LFCS exam, this scenario tests your understanding of Linux file permissions and how the effective user of a service determines access. A common trap is assuming that file permissions alone matter—remember, directory write permission controls file creation. Memory tip: "To log in, you need write on the bin" — for a service to write logs, it needs the 'w' bit on the directory, not just the file.
LFCS Service Configuration Practice Question
This LFCS practice question tests your understanding of service configuration. 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 developer reports that a web application's logs are not being written to /var/log/myapp.log. The service runs as user 'myapp' and the log directory /var/log/myapp/ has permissions 755 owned by root. What is the most likely cause?
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 service user 'myapp' does not have write permission to the log directory.
Option D is correct because the /var/log/myapp/ directory has permissions 755, which grants read and execute access to the 'others' category but not write. Since the service runs as user 'myapp', which is not the owner (root) and not in the root group, it falls under 'others' and thus lacks write permission. Without write permission on the directory, the service cannot create or write to /var/log/myapp.log, even if the file itself might have different permissions.
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.
✗
AppArmor is denying access.
Why it's wrong here
AppArmor is not standard on many distributions and not indicated.
✗
SELinux is blocking the write.
Why it's wrong here
SELinux could be a factor, but without evidence, the permissions issue is more direct.
✗
The service is logging to systemd-journald instead of a file.
Why it's wrong here
The application is configured to write to a file, not journald.
✓
The service user 'myapp' does not have write permission to the log directory.
Why this is correct
The directory is owned by root with 755, so only root can write; myapp needs write permission.
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.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may focus on file permissions of the log file itself rather than the directory permissions, or incorrectly assume that SELinux or AppArmor is the default cause for permission denials without evidence of their enforcement.
Detailed technical explanation
How to think about this question
Under Linux, directory permissions control the ability to create, delete, or rename files within that directory. The write bit on a directory (w) is required to add new files, regardless of the file's own permissions. In this scenario, the 'myapp' user needs the write permission on /var/log/myapp/ to create or modify /var/log/myapp.log. A common real-world scenario is when a service runs under a non-root user and the log directory is created by root with restrictive permissions, causing silent failures that are only visible in the service's stderr or system logs.
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.
Service Configuration — This question tests Service Configuration — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The service user 'myapp' does not have write permission to the log directory. — Option D is correct because the /var/log/myapp/ directory has permissions 755, which grants read and execute access to the 'others' category but not write. Since the service runs as user 'myapp', which is not the owner (root) and not in the root group, it falls under 'others' and thus lacks write permission. Without write permission on the directory, the service cannot create or write to /var/log/myapp.log, even if the file itself might have different permissions.
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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