System resource monitoring (free, uptime, vmstat) in Linux CLI - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to display the total and free memory on the system.

Linux CLI

free [1]

Drag options to blanks, or click blank then click option'

A-m

B-x

C-z

D-q

Attempts:

3 left

💡 Hint

Common Mistakes

Using options that do not display memory in a readable format.

Omitting the option and getting output in bytes.

The -m option shows memory in megabytes, making it easier to read total and free memory.

2fill in blank

medium

Complete the code to show how long the system has been running.

Linux CLI

uptime [1]

Drag options to blanks, or click blank then click option'

A-p

B-t

C-s

D-v

Attempts:

3 left

💡 Hint

Common Mistakes

Using uptime without options which shows more info than needed.

Using -s which shows boot time, not uptime duration.

The -p option shows the uptime in a pretty, human-readable format.

3fill in blank

hard

Fix the error in the command to display CPU and memory statistics every 2 seconds.

Linux CLI

vmstat [1] 5

Drag options to blanks, or click blank then click option'

A-s

B-2

C2

Ds

Attempts:

3 left

💡 Hint

Common Mistakes

Using a dash before the interval number causes an error.

Using letters instead of numbers for interval.

To display stats every 2 seconds, provide the interval as the first argument without a dash.

4fill in blank

hard

Fill both blanks to create a command that shows memory usage in kilobytes and updates every 3 seconds.

Linux CLI

free [1] [2] 3

Drag options to blanks, or click blank then click option'

A-k

B-m

C-s

D-h

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up units and interval options.

Using -m instead of -k for kilobytes.

-k shows memory in kilobytes, and -s followed by a number sets the update interval in seconds.

5fill in blank

hard

Fill all three blanks to create a vmstat command that shows statistics every 4 seconds, 6 times, and displays summary since boot.

Linux CLI

vmstat [1] [2] [3]

Drag options to blanks, or click blank then click option'

A4

B6

C-s

D-m

Attempts:

3 left

💡 Hint

Common Mistakes

Using options instead of numbers for interval and count.

Omitting the summary option.

The first two numbers set the interval and count, and -s shows a summary of memory stats since boot.

Practice

1. What does the free command primarily display on a Linux system?

easy

A. System uptime and load average

B. Disk usage statistics

C. CPU temperature

D. Memory usage and availability

Solution

1. Step 1: Understand the purpose of free

   The free command shows information about the system's memory usage, including total, used, free, and available memory.

2. Step 2: Compare with other commands

   uptime shows system running time and load, vmstat shows detailed CPU and memory stats, but free focuses on memory.

3. Final Answer:

   Memory usage and availability -> Option D

4. Quick Check:

   free = Memory info [OK]

Hint: Remember: free = memory info, uptime = running time [OK]

Common Mistakes:

• Confusing free with uptime output
• Thinking free shows CPU or disk info
• Mixing vmstat details with free

2. Which of the following is the correct syntax to display memory usage in megabytes using the free command?

easy

A. free -k

B. free -m

C. free -g

D. free --bytes

Solution

1. Step 1: Identify the option for megabytes

   The -m option in free shows memory in megabytes.

2. Step 2: Check other options

   --bytes shows bytes, -g shows gigabytes, -k shows kilobytes. So -m is correct for MB.

3. Final Answer:

   free -m -> Option B

4. Quick Check:

   free -m = megabytes [OK]

Hint: Use -m for MB, -k for KB, -g for GB in free [OK]

Common Mistakes:

• Using -k expecting MB output
• Confusing --bytes with -m
• Using wrong option like -g for MB

3. What output will the command uptime produce on a system that has been running for 3 days, 4 hours, 12 minutes with load averages 0.15, 0.10, 0.05?

medium

A. 10:30:00 up 3 days, 4:12, 1 user, load average: 0.15, 0.10, 0.05

B. 3 days, 4 hours, 12 minutes uptime with load 0.15, 0.10, 0.05

C. uptime: 3d 4h 12m, load: 0.15 0.10 0.05

D. System up for 3 days 4 hours 12 minutes, load averages: 0.15 0.10 0.05

Solution

1. Step 1: Understand uptime output format

   The uptime command shows current time, system uptime in days and hours:minutes, number of users, and load averages.

2. Step 2: Match given data to output style

   The correct format includes current time, "up 3 days, 4:12", user count, and load averages separated by commas.

3. Final Answer:

   10:30:00 up 3 days, 4:12, 1 user, load average: 0.15, 0.10, 0.05 -> Option A

4. Quick Check:

   uptime shows time, up, users, load [OK]

Hint: Look for 'up' and load averages format in uptime output [OK]

Common Mistakes:

• Expecting uptime to print in verbose sentences
• Missing commas or user count in output
• Confusing uptime with other commands

4. You run vmstat 1 3 but get an error saying "command not found". What is the most likely cause?

medium

A. vmstat is not installed on the system

B. The interval must be greater than 1 second

C. The command syntax is incorrect; count must be last

D. You need to run vmstat as root user

Solution

1. Step 1: Verify vmstat syntax

   vmstat 1 3 uses correct syntax: 1-second delay, 3 samples.

2. Step 2: Analyze the error

   "command not found" means vmstat (from procps package) is not installed.

3. Final Answer:

   vmstat is not installed on the system -> Option A

4. Quick Check:

   command not found = not installed [OK]

Hint: vmstat missing? Install procps package [OK]

Common Mistakes:

• Assuming syntax error for missing command
• Thinking root needed for vmstat
• Believing interval too small

5. You want to monitor CPU and memory usage every 2 seconds for 5 samples using vmstat. Which command will correctly do this and what will be the total monitoring time?

hard

A. vmstat 2 5; total time 10 seconds

B. vmstat 5 2; total time 10 seconds

C. vmstat 2 5; total time 8 seconds

D. vmstat 5 2; total time 8 seconds

Solution

1. Step 1: Understand vmstat interval and count

   vmstat 2 5 runs vmstat every 2 seconds, 5 times total.

2. Step 2: Calculate total monitoring time

   vmstat prints the first line immediately, then 4 intervals of 2 seconds each, so total time = 2 * (5 - 1) = 8 seconds.

3. Final Answer:

   vmstat 2 5; total time 8 seconds -> Option C

4. Quick Check:

   Total time = interval * (count - 1) [OK]

Hint: Total time = interval x (count - 1) for vmstat [OK]

Common Mistakes:

• Multiplying interval by count instead of count-1
• Swapping interval and count values
• Assuming total time equals interval x count