LFCS Operation of Running Systems Practice Question
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?
⚠ Common exam trap
Candidates often 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.
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 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.
Answer analysis
Option-by-option breakdown
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 virtual memory statistics as raw numeric columns in kilobytes, not human-readable totals of used and free memory. It suits sampling paging, swap and CPU activity over intervals, but the stem requires a formatted summary of total, used and free memory, which free delivers.
- ✓
free -h
Why this is correct
`free -h` reads `/proc/meminfo` and prints used, free, shared, buff/cache and available memory, with the `-h` flag scaling values into human-readable units such as MiB and GiB. This directly satisfies the stem's requirement for totals in a readable format, unlike `-b`, `-k` or `-m`, which force fixed byte, KiB or MiB units.
- ✗
top
Why it's wrong here
top reports per-process CPU and memory with a summary line, not a dedicated totals view; its memory figures are derived and less precise for free/used breakdowns. It is the right tool for live per-process CPU monitoring, but the stem asks for human-readable total memory usage, which free provides directly.
- ✗
cat /proc/meminfo
Why it's wrong here
/proc/meminfo exposes raw kernel counters in kilobytes with no human-readable formatting or used/free totals; it is intended for scripts and tools parsing MemTotal and MemAvailable. The stem asks for a formatted summary, which free -h provides directly.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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