LFCS Essential Commands Practice Question
Which command displays the amount of free and used memory in the system?
⚠ Common exam trap
Candidates often confuse `df` (disk free) with `free` (memory free) due to similar names, or assume `ps aux` shows total memory usage when it only shows per-process values.
Answer choices
Why each option matters
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 the total, used, and free physical memory (RAM) and swap space in a human-readable format (e.g., GiB, MiB). The `-h` flag converts raw byte counts into appropriate units, making it the correct tool for checking memory usage.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
free -h
Why this is correct
free displays memory usage.
- ✗
df -h
Why it's wrong here
df shows disk space.
- ✗
ps aux
Why it's wrong here
ps shows process information.
- ✗
netstat -i
Why it's wrong here
netstat shows network interfaces.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.