Quick Answer
The answer is `ps aux --sort=-%mem`. This command is correct because it lists all processes with detailed information and sorts them by the `%MEM` column in descending order, placing the most memory-intensive process at the top. The `-%mem` flag applies reverse sorting to the memory percentage, which directly addresses the need to identify the process using the most memory on a Linux server. On the CompTIA Linux+ XK0-005 exam, this question tests your ability to interpret process monitoring tools and sort output efficiently, often appearing as a scenario where you must quickly pinpoint a memory leak or runaway process. A common trap is confusing `ps aux` with `ps -ef` or forgetting the sort syntax—`--sort` requires a hyphen before the column name to reverse order. Remember the mnemonic "Minus Mem Means Most" to recall that `-%mem` shows the highest memory usage first.
This XK0-005 practice question tests your understanding of system management. 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.
A system administrator needs to determine which process is using the most memory on a Linux server. Which command should be used to display processes sorted by memory usage?
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.
top -o %MEM
Why wrong: top is interactive and not ideal for scripting.
vmstat 1 5
Why wrong: Shows system statistics, not per process memory.
ps aux --sort=-%mem
Correctly sorts processes by memory usage descending.
free -m
Why wrong: Shows overall memory usage, not per process.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
ps aux --sort=-%mem
Option C is correct because `ps aux --sort=-%mem` lists all processes with detailed information and sorts them by memory usage in descending order, showing the most memory-intensive process first. The `-%mem` flag specifies sorting by the %MEM column (resident set size as a percentage of total physical memory) in reverse order, which directly answers the requirement to determine which process is using the most memory.
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.
top -o %MEM
Why it's wrong here
top is interactive and not ideal for scripting.
vmstat 1 5
Why it's wrong here
Shows system statistics, not per process memory.
ps aux --sort=-%mem
Why this is correct
Correctly sorts processes by memory usage descending.
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.
free -m
Why it's wrong here
Shows overall memory usage, not per process.
Common exam traps
CompTIA often tests the distinction between commands that show system-wide memory statistics (like `free` or `vmstat`) versus commands that display per-process memory usage (like `ps` or `top`), and candidates may mistakenly choose `free -m` because it shows memory usage, even though it does not identify which process is consuming the most memory.
Trap categories for this question
Command / output trap
Shows system statistics, not per process memory.
Detailed technical explanation
The `ps` command reads process information from the `/proc` filesystem, which contains per-process directories with memory usage data in files like `/proc/[pid]/status` and `/proc/[pid]/smaps`. The `--sort` option accepts multiple keys with a leading `+` or `-` for ascending or descending order, and `%mem` is calculated as (RSS / total physical memory) * 100, where RSS (Resident Set Size) is the portion of a process's memory held in RAM. In real-world scenarios, this command is critical for identifying memory leaks or runaway processes that could degrade server performance.
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 XK0-005 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
System Management — This question tests System Management — Read the scenario before looking for a memorised answer..
The correct answer is: ps aux --sort=-%mem — Option C is correct because `ps aux --sort=-%mem` lists all processes with detailed information and sorts them by memory usage in descending order, showing the most memory-intensive process first. The `-%mem` flag specifies sorting by the %MEM column (resident set size as a percentage of total physical memory) in reverse order, which directly answers the requirement to determine which process is using the most memory.
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 30, 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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