System resource monitoring (free, uptime, vmstat) in Linux CLI - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What does the command free -m output?

You run free -m on a Linux system. What does the Mem: line show?

Linux CLI

free -m

A CPU usage percentages for user, system, and idle

B Memory usage in megabytes including total, used, free, shared, buff/cache, and available

C Disk space usage in megabytes for all mounted filesystems

D Network interface statistics including packets sent and received

💡 Hint

Think about what 'free' command is designed to show about system memory.

The free -m command shows memory usage in megabytes. The Mem: line lists total memory, used memory, free memory, shared memory, buffers/cache, and available memory.

💻 Command Output

intermediate

What does the uptime command output?

You run uptime on a Linux system. Which of the following best describes the output?

Linux CLI

uptime

A Network connections and their states

B List of running processes with CPU and memory usage

C Current time, system uptime, number of users logged in, and load averages for 1, 5, and 15 minutes

D Disk usage statistics for mounted filesystems

💡 Hint

Think about what 'uptime' means for a system.

The uptime command shows how long the system has been running, current time, how many users are logged in, and the system load averages over 1, 5, and 15 minutes.

💻 Command Output

advanced

What does the vmstat 1 2 command output show?

You run vmstat 1 2. What does the second line of output represent?

Linux CLI

vmstat 1 2

A System performance statistics averaged over the last 1 second interval

B Initial system statistics since boot time

C Disk usage summary for the last 2 seconds

D Network packet statistics for the last 1 second

💡 Hint

The first line of vmstat output is a summary since boot, the next lines are interval samples.

The first line of vmstat output shows averages since boot. The second line shows statistics for the last 1 second interval, which is the sampling period.

❓ Troubleshoot

advanced

Why does free -m show low free memory but high available memory?

You notice free -m shows low free memory but high available memory. What is the most likely explanation?

A Linux uses free memory for cache and buffers, which can be freed when needed

B The system is running out of memory and will soon crash

C There is a memory leak in the kernel causing incorrect reporting

D The command is showing swap memory instead of RAM

💡 Hint

Think about how Linux manages memory for performance.

Linux uses free memory to cache files and buffers to speed up access. This memory is counted as used but can be freed quickly, so available memory is a better indicator of free memory.

✅ Best Practice

expert

Which command combination gives a real-time view of CPU, memory, and process info?

You want to monitor CPU usage, memory usage, and running processes in real-time on a Linux system. Which command or combination is best?

A Run <code>free -m</code> repeatedly in a loop

B Check <code>uptime</code> every minute

C Use <code>vmstat 5</code> alone without any other tool

D Use <code>top</code> command which shows CPU, memory, and process info live

💡 Hint

Think about a tool that shows multiple system stats live in one place.

The top command provides a live, interactive view of CPU usage, memory usage, and running processes, making it ideal for real-time monitoring.