Network monitoring script in Bash Scripting - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to ping a host once and check if it is reachable.

Bash Scripting

ping -c [1] 8.8.8.8

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

A1

B5

C0

D10

Attempts:

3 left

💡 Hint

Common Mistakes

Using 0 or no count sends unlimited pings.

Using too many pings delays the check.

The -c option specifies the number of ping requests to send. Using 1 sends a single ping.

2fill in blank

medium

Complete the code to store the ping command's exit status in a variable.

Bash Scripting

ping -c 1 8.8.8.8
status=[1]

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

A$!

B$?

C$#

D$$

Attempts:

3 left

💡 Hint

Common Mistakes

Using $! which holds the last background process ID.

Using $$ which holds the current script's PID.

The special variable $? holds the exit status of the last command run.

3fill in blank

hard

Fix the error in the if statement to check if the ping was successful.

Bash Scripting

if [ [1] -eq 0 ]; then
  echo "Host is reachable"
else
  echo "Host is unreachable"
fi

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

Astatus

B$?status

C$status

Dstatus$

Attempts:

3 left

💡 Hint

Common Mistakes

Using variable name without $ causes string comparison, not numeric.

Adding $ in wrong place causes syntax error.

Variables in bash must be prefixed with $ to get their value inside conditions.

4fill in blank

hard

Fill both blanks to create a loop that pings a host 3 times and prints the result each time.

Bash Scripting

for i in [1]; do
  ping -c 1 8.8.8.8
  result=$?
  if [ $result [2] 0 ]; then
    echo "Ping $i: Success"
  else
    echo "Ping $i: Fail"
  fi
done

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

A"1 2 3"

B==

C-eq

D1 2 3

Attempts:

3 left

💡 Hint

Common Mistakes

Using quotes around numbers makes the loop treat it as one string.

Using == instead of -eq causes numeric comparison errors.

The loop iterates over the numbers 1 2 3 (without quotes). The numeric comparison operator for equality in bash is -eq.

5fill in blank

hard

Fill all three blanks to create a script that logs ping results with timestamps to a file.

Bash Scripting

for i in [1]; do
  ping -c 1 8.8.8.8 > /dev/null
  status=$?
  echo "$(date [2]) Ping $i: $[3]" >> ping_log.txt
done

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

A1 2 3 4 5

B"+%Y-%m-%d %H:%M:%S"

Cstatus

Dresult

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong variable name for status.

Not quoting the date format string.

Using too few or too many loop iterations.

The loop runs 5 times. The date command uses the format string "+%Y-%m-%d %H:%M:%S" for timestamps. The variable holding ping success is status.

Practice

1. What is the main purpose of a network monitoring script using ping?

easy

A. To increase the speed of the network

B. To install software on remote devices

C. To change the IP addresses of devices

D. To check if devices on the network are reachable

Solution

1. Step 1: Understand the role of ping

   ping sends a small message to a device to see if it replies, showing if it is reachable.

2. Step 2: Identify the script's goal

   The script uses ping to detect if devices respond, helping find network problems early.

3. Final Answer:

   To check if devices on the network are reachable -> Option D

4. Quick Check:

   Ping checks reachability = B [OK]

Hint: Ping tests if a device replies to confirm reachability [OK]

Common Mistakes:

• Confusing ping with speed testing
• Thinking ping changes device settings
• Assuming ping installs software

2. Which of the following is the correct syntax to ping a device once in a bash script?

easy

A. ping /c 1 192.168.1.1

B. ping -n 1 192.168.1.1

C. ping -c 1 192.168.1.1

D. ping 192.168.1.1 -count 1

Solution

1. Step 1: Recall the ping option for count

   In Linux bash, -c specifies the number of ping requests to send.

2. Step 2: Verify the correct command format

   ping -c 1 192.168.1.1 sends exactly one ping to the IP address.

3. Final Answer:

   ping -c 1 192.168.1.1 -> Option C

4. Quick Check:

   Use -c for count in ping = D [OK]

Hint: Use -c to specify ping count in bash [OK]

Common Mistakes:

• Using Windows ping options like -n in bash
• Incorrect option syntax like /c or -count
• Omitting the count option for single ping

3. What will be the output of this script snippet?

if ping -c 1 8.8.8.8 > /dev/null; then
  echo "Host is reachable"
else
  echo "Host is unreachable"
fi

medium

A. Host is reachable

B. Syntax error

C. Host is unreachable

D. No output

Solution

1. Step 1: Understand the ping command behavior

   The command ping -c 1 8.8.8.8 sends one ping to Google's DNS server, which is usually reachable.

2. Step 2: Analyze the if condition and output

   If ping succeeds, the script prints "Host is reachable"; otherwise, it prints "Host is unreachable".

3. Final Answer:

   Host is reachable -> Option A

4. Quick Check:

   Successful ping prints reachable = C [OK]

Hint: Ping 8.8.8.8 usually succeeds, so output is reachable [OK]

Common Mistakes:

• Assuming ping always fails
• Confusing output redirection with errors
• Missing that output is suppressed with > /dev/null

4. Identify the error in this script snippet for monitoring a device:

for ip in 192.168.1.1 192.168.1.2
 do
  ping -c 1 $ip
  if [ $? -eq 0 ]; then
    echo "$ip is up"
  else
    echo "$ip is down"
  fi

medium

A. Incorrect ping option '-c'

B. Missing 'done' to close the for loop

C. Wrong variable name for IP address

D. No error, script is correct

Solution

1. Step 1: Check for loop syntax completeness

   The for loop starts with for ip in ... but lacks the closing done keyword.

2. Step 2: Confirm other parts are correct

   The ping command and if condition use correct syntax and variable names.

3. Final Answer:

   Missing 'done' to close the for loop -> Option B

4. Quick Check:

   For loops need 'done' to end = A [OK]

Hint: Always end bash loops with 'done' [OK]

Common Mistakes:

• Forgetting 'done' after loops
• Using wrong ping options
• Using undefined variables

5. You want to create a script that checks multiple IPs and logs only unreachable ones to a file named unreachable.log. Which snippet correctly does this?

hard

A. for ip in 192.168.1.1 192.168.1.2; do
ping -c 1 $ip > /dev/null || echo "$ip unreachable" >> unreachable.log
done

B. for ip in 192.168.1.1 192.168.1.2; do
if ping -c 1 $ip > /dev/null; then
echo "$ip unreachable" >> unreachable.log
fi
done

C. for ip in 192.168.1.1 192.168.1.2; do
ping -c 1 $ip >> unreachable.log
done

D. for ip in 192.168.1.1 192.168.1.2; do
ping -c 1 $ip || echo "$ip reachable" >> unreachable.log
done

Solution

1. Step 1: Understand the goal

   The script should log only unreachable IPs to unreachable.log.

2. Step 2: Analyze each option

   for ip in 192.168.1.1 192.168.1.2; do ping -c 1 $ip > /dev/null || echo "$ip unreachable" >> unreachable.log done uses ping -c 1 $ip > /dev/null || echo "$ip unreachable" >> unreachable.log, which logs IPs only if ping fails (unreachable). for ip in 192.168.1.1 192.168.1.2; do if ping -c 1 $ip > /dev/null; then echo "$ip unreachable" >> unreachable.log fi done logs reachable IPs incorrectly. for ip in 192.168.1.1 192.168.1.2; do ping -c 1 $ip >> unreachable.log done logs all ping output, not just unreachable. for ip in 192.168.1.1 192.168.1.2; do ping -c 1 $ip || echo "$ip reachable" >> unreachable.log done logs reachable IPs as unreachable.

3. Final Answer:

   for ip in 192.168.1.1 192.168.1.2; do ping -c 1 $ip > /dev/null || echo "$ip unreachable" >> unreachable.log done -> Option A

4. Quick Check:

   Use '||' to log failures only = A [OK]

Hint: Use '||' to log only when ping fails [OK]

Common Mistakes:

• Logging reachable IPs instead of unreachable
• Appending all ping output to log
• Using wrong conditional logic