This LFCS practice question tests your understanding of operation of running systems. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
An administrator wants to view the current memory usage in a human-readable format, showing totals for used and free memory. Which command should be used?
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.
vmstat
Why wrong: Shows system statistics including memory but not a concise summary.
free -h
Shows human-readable memory summary.
top
Why wrong: Interactive process viewer, not a static memory summary.
cat /proc/meminfo
Why wrong: Raw data, not human-readable by default.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
free -h
The `free -h` command displays memory usage in a human-readable format (e.g., MiB, GiB) and shows totals for used and free memory, including buffers/cache and swap. This directly matches the requirement for a quick, readable summary of memory usage.
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.
vmstat
Why it's wrong here
Shows system statistics including memory but not a concise summary.
free -h
Why this is correct
Shows human-readable memory summary.
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.
top
Why it's wrong here
Interactive process viewer, not a static memory summary.
cat /proc/meminfo
Why it's wrong here
Raw data, not human-readable by default.
Common exam traps
The trap here is that candidates may choose `cat /proc/meminfo` because it contains all memory details, but they overlook the requirement for a human-readable format and totals, which `free -h` provides directly.
Trap categories for this question
Command / output trap
Shows system statistics including memory but not a concise summary.
Detailed technical explanation
The `free` command reads memory information from `/proc/meminfo` and calculates used/free values, including adjustments for buffers/cache. The `-h` flag uses powers of 1024 (binary) for human-readable output, aligning with the `--si` flag for decimal if needed. In real-world scenarios, `free -h` is preferred for quick checks, while `/proc/meminfo` is used for scripting or detailed analysis.
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.
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FAQ
Operation of Running Systems — This question tests Operation of Running Systems — Read the scenario before looking for a memorised answer..
The correct answer is: free -h — The `free -h` command displays memory usage in a human-readable format (e.g., MiB, GiB) and shows totals for used and free memory, including buffers/cache and swap. This directly matches the requirement for a quick, readable summary of memory usage.
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 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.
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