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.
Refer to the exhibit. The administrator receives alerts that the root filesystem is almost full. Which command could free up space by removing old log files?
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.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
find /var/log -name '*.log' -mtime +30 -delete
Option A is correct because the `find` command with `-name '*.log'` targets log files, `-mtime +30` selects files modified more than 30 days ago, and `-delete` removes them. This safely frees space by purging only old logs, preserving recent logs needed for troubleshooting.
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.
✓
find /var/log -name '*.log' -mtime +30 -delete
Why this is correct
Removes old log files safely.
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.
✗
truncate -s 0 /var/log/syslog
Why it's wrong here
Only truncates one file, not all old logs.
✗
rm -rf /var/log/*
Why it's wrong here
Removes all log files, including current ones, potentially causing data loss.
✗
du -sh /var/log
Why it's wrong here
Shows disk usage but does not free space.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Linux Foundation often tests the distinction between commands that merely display disk usage (like `du`) versus those that actually remove files, and the danger of using `rm -rf` with wildcards on system directories like /var/log.
Trap categories for this question
Command / output trap
Shows disk usage but does not free space.
Detailed technical explanation
How to think about this question
The `find` command with `-mtime +30` uses the file's modification timestamp (mtime) measured in days; files modified exactly 30 days ago are not included due to the `+` prefix. The `-delete` action is efficient and avoids race conditions compared to piping to `xargs rm`, but it should be used carefully to avoid unintended deletions. In real-world scenarios, log rotation (e.g., logrotate) is typically configured to handle old logs, but manual cleanup with `find` is useful when rotation fails or disk space is critically low.
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 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
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: find /var/log -name '*.log' -mtime +30 -delete — Option A is correct because the `find` command with `-name '*.log'` targets log files, `-mtime +30` selects files modified more than 30 days ago, and `-delete` removes them. This safely frees space by purging only old logs, preserving recent logs needed for troubleshooting.
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: "which command". Tests specific CLI syntax. Recall the exact command and its required context — near-synonyms and partial matches are common distractors.
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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