Quick Answer
The answer is the `free` command and reading `/proc/meminfo` with `cat`. Both tools display the amount of free and used memory on a Linux system, but they do so in different ways: `free` provides a human-readable summary of total, used, and available RAM and swap, while `/proc/meminfo` is a virtual file maintained by the kernel that offers granular, real-time memory statistics. On the LPIC-1 exam, this question tests your ability to distinguish between commands that report memory usage versus those that modify it, with a common trap being candidates who confuse `free` with `vmstat` or `top`, which show memory but also include process or CPU data. Remember that `free` is the dedicated command for a quick snapshot, whereas `cat /proc/meminfo` gives you the raw kernel data for deeper analysis. A useful memory tip: think of `free` as the friendly summary, and `/proc/meminfo` as the engineer’s blueprint—both are correct, but each serves a different purpose.
This LPIC-1 practice question tests your understanding of system architecture. 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.
Which TWO commands can be used to display the amount of free and used memory on a Linux system? (Select exactly 2.)
vmstat
Why wrong: vmstat reports memory, but it's less common than free.
du
Why wrong: du reports disk usage, not memory.
cat /proc/meminfo
Directly reads kernel memory information.
free
free displays memory usage in a concise format.
top
Why wrong: top shows processes and memory but is interactive; not a direct memory display command.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
cat /proc/meminfo
Option C is correct because `/proc/meminfo` is a virtual file maintained by the kernel that provides detailed, real-time memory statistics, including total, free, available, and used memory. Reading this file with `cat` directly displays the current memory usage without any additional processing.
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
vmstat reports memory, but it's less common than free.
du
Why it's wrong here
du reports disk usage, not memory.
cat /proc/meminfo
Why this is correct
Directly reads kernel memory information.
Related concept
Read the scenario before looking for a memorised answer.
free
Why this is correct
free displays memory usage in a concise format.
Related concept
Read the scenario before looking for a memorised answer.
top
Why it's wrong here
top shows processes and memory but is interactive; not a direct memory display command.
Common exam traps
The trap here is that candidates may confuse `du` (disk usage) with memory reporting, or assume `vmstat` or `top` are primary tools for a simple free/used memory display, when `free` and `/proc/meminfo` are the direct and standard answers.
Trap categories for this question
Command / output trap
top shows processes and memory but is interactive; not a direct memory display command.
Detailed technical explanation
The `/proc/meminfo` file exposes kernel memory management data, including `MemTotal`, `MemFree`, `MemAvailable`, `Buffers`, `Cached`, and `SwapTotal`/`SwapFree`. The `free` command reads `/proc/meminfo` and formats the output into a user-friendly table, showing used memory as `total - free - buffers/cache`. In real-world troubleshooting, `free -h` is often used for quick checks, while `cat /proc/meminfo` provides granular details for debugging memory leaks or kernel slab allocations.
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 LPIC-1 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
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FAQ
System Architecture — This question tests System Architecture — Read the scenario before looking for a memorised answer..
The correct answer is: cat /proc/meminfo — Option C is correct because `/proc/meminfo` is a virtual file maintained by the kernel that provides detailed, real-time memory statistics, including total, free, available, and used memory. Reading this file with `cat` directly displays the current memory usage without any additional processing.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 11, 2026
This LPIC-1 practice question is part of Courseiva's free LPI 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 LPIC-1 exam.
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