Why conditionals branch script logic in Bash Scripting - Challenge Your Understanding

Challenge - 5 Problems

💻 Command Output

intermediate

What is the output of this Bash script with conditionals?

Consider the following Bash script. What will it print when run?

Bash Scripting

count=5
if [ $count -gt 3 ]; then
  echo "Count is greater than 3"
else
  echo "Count is 3 or less"
fi

A Syntax error

B Count is 3 or less

C Count is greater than 3

D No output

💡 Hint

Check the condition if count is greater than 3.

The variable count is 5, which is greater than 3, so the if condition is true and the first echo runs.

💻 Command Output

intermediate

What output does this nested conditional produce?

What will this Bash script print?

Bash Scripting

value=10
if [ $value -lt 5 ]; then
  echo "Less than 5"
elif [ $value -eq 10 ]; then
  echo "Equal to 10"
else
  echo "Other value"
fi

A Equal to 10

B Less than 5

C Other value

D Syntax error

💡 Hint

Check the elif condition carefully.

The value is 10, so the first if is false, but the elif condition is true, so it prints 'Equal to 10'.

🔧 Debug

advanced

Why does this Bash script fail to run?

This script is intended to print "Positive" if the number is greater than zero, but it fails. What is the error?

Bash Scripting

num=3
if [ $num -gt 0 ]; then
  echo "Positive"
fi

A No output because condition is false

B Runs correctly and prints "Positive"

C Runtime error: variable not defined

D Syntax error due to incorrect comparison operator

💡 Hint

Check the operator used inside the square brackets.

In Bash, '>' is a redirection operator, not a numeric comparison. The correct operator is '-gt'.

💻 Command Output

advanced

What does this script print with multiple conditions?

What is the output of this Bash script?

Bash Scripting

score=75
if [ $score -ge 90 ]; then
  echo "Grade A"
elif [ $score -ge 80 ]; then
  echo "Grade B"
elif [ $score -ge 70 ]; then
  echo "Grade C"
else
  echo "Grade F"
fi

A Grade C

B Grade A

C Grade B

D Grade F

💡 Hint

Check which condition matches the score first.

Score 75 is not >= 90 or 80, but it is >= 70, so it prints 'Grade C'.

💻 Command Output

expert

What is the output of this Bash script using logical AND in condition?

What will this script print?

Bash Scripting

a=5
b=10
if [ $a -lt 10 ] && [ $b -gt 5 ]; then
  echo "Both conditions true"
else
  echo "One or both conditions false"
fi

A One or both conditions false

B Both conditions true

C Syntax error due to missing semicolon

D No output

💡 Hint

Both conditions must be true for the if to run.

a=5 is less than 10 and b=10 is greater than 5, so both conditions are true and it prints 'Both conditions true'.

Practice

1. What is the main purpose of using if statements in a bash script?

easy

A. To make decisions and run different commands based on conditions

B. To repeat commands multiple times

C. To define functions

D. To declare variables

Solution

1. Step 1: Understand the role of if in scripts

   if statements check conditions and decide which commands to run next.

2. Step 2: Compare with other options

   Repeating commands is done by loops, functions define reusable code, and variables store data, so these are not the main purpose of if.

3. Final Answer:

   To make decisions and run different commands based on conditions -> Option A

4. Quick Check:

   Conditionals branch logic = A [OK]

Hint: If it chooses what to do next, it's an if statement [OK]

Common Mistakes:

• Confusing if with loops
• Thinking if defines functions
• Mixing variable declaration with conditionals

2. Which of the following is the correct syntax to start an if statement in bash?

easy

A. if condition {}

B. if (condition) {

C. if condition then

D. if [ condition ]; then

Solution

1. Step 1: Recall bash if syntax

   Bash requires square brackets around the condition and a semicolon before then.

2. Step 2: Check other options for syntax errors

   Options A, B, and C use incorrect syntax styles not valid in bash.

3. Final Answer:

   if [ condition ]; then -> Option D

4. Quick Check:

   Bash if syntax = D [OK]

Hint: Remember: if [ condition ]; then is bash style [OK]

Common Mistakes:

• Omitting semicolon before then
• Using parentheses instead of brackets
• Missing brackets around condition

3. What will be the output of this script?

#!/bin/bash
num=5
if [ $num -gt 10 ]; then
  echo "Greater than 10"
elif [ $num -eq 5 ]; then
  echo "Equals 5"
else
  echo "Less than 5"
fi

medium

A. Equals 5

B. Greater than 10

C. Less than 5

D. No output

Solution

1. Step 1: Check the value of num

   The variable num is set to 5.

2. Step 2: Evaluate the conditions in order

   First condition checks if 5 > 10 (false), second checks if 5 == 5 (true), so it prints "Equals 5".

3. Final Answer:

   Equals 5 -> Option A

4. Quick Check:

   num=5 matches elif condition = A [OK]

Hint: Check conditions top to bottom; first true runs [OK]

Common Mistakes:

• Assuming first condition is true
• Ignoring elif branch
• Confusing numeric comparison operators

4. Identify the error in this bash conditional snippet:

if [ $value = 10 ]; then
  echo "Value is 10"
fi

medium

A. Missing semicolon before then

B. Using single equals for numeric comparison

C. Brackets should be double [[ ]]

D. No error, script runs fine

Solution

1. Step 1: Understand comparison operators in bash

   For numeric comparison inside [ ], use -eq instead of =.

2. Step 2: Check the snippet

   The snippet uses = which is for string comparison, so numeric comparison is incorrect here.

3. Final Answer:

   Using single equals for numeric comparison -> Option B

4. Quick Check:

   Numeric compare needs -eq not = [OK]

Hint: Use -eq for numbers, = for strings in [ ] [OK]

Common Mistakes:

• Confusing string and numeric operators
• Thinking = works for numbers
• Ignoring bash operator rules

5. You want a script to print "Positive", "Zero", or "Negative" based on a variable num. Which conditional structure correctly branches all cases?

hard

A. if [ $num -ge 0 ]; then echo "Positive"; else echo "Negative"; fi

B. if [ $num = 0 ]; then echo "Zero"; else echo "Non-zero"; fi

C. if [ $num -gt 0 ]; then echo "Positive"; elif [ $num -eq 0 ]; then echo "Zero"; else echo "Negative"; fi

D. if [ $num -lt 0 ]; then echo "Negative"; elif [ $num -gt 0 ]; then echo "Positive"; fi

Solution

1. Step 1: Identify all required cases

   We need to handle positive (>0), zero (=0), and negative (<0) values.

2. Step 2: Check each option for coverage

   if [ $num -gt 0 ]; then echo "Positive"; elif [ $num -eq 0 ]; then echo "Zero"; else echo "Negative"; fi covers all three cases with if, elif, else branches. Others miss zero or one case.

3. Final Answer:

   if [ $num -gt 0 ]; then echo "Positive"; elif [ $num -eq 0 ]; then echo "Zero"; else echo "Negative"; fi -> Option C

4. Quick Check:

   All cases covered with if-elif-else = B [OK]

Hint: Use if-elif-else to cover all conditions [OK]

Common Mistakes:

• Missing zero case
• Using wrong comparison operators
• Not using else for last case