if-elif-else in Bash Scripting - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

Output of a simple if-elif-else script

What is the output of this Bash script when run with argument 15?

Bash Scripting

#!/bin/bash
num=$1
if [ "$num" -lt 10 ]; then
  echo "Less than 10"
elif [ "$num" -lt 20 ]; then
  echo "Between 10 and 19"
else
  echo "20 or more"
fi

A Less than 10

B Syntax error

C 20 or more

D Between 10 and 19

💡 Hint

Check the numeric comparison operators and the order of conditions.

The script checks if the number is less than 10, then less than 20. Since 15 is not less than 10 but less than 20, it prints 'Between 10 and 19'.

🔧 Debug

intermediate

Identify the error in this if-elif-else script

What error will this Bash script produce when run?

Bash Scripting

#!/bin/bash
num=5
if [ $num < 10 ]; then
  echo "Less than 10"
elif [ $num < 20 ]; then
  echo "Between 10 and 19"
else
  echo "20 or more"
fi

A Runs correctly and prints 'Less than 10'

B Syntax error due to incorrect comparison operator

C Runtime error: command not found

D Prints '20 or more'

💡 Hint

Check the comparison operators used inside the test brackets.

In Bash, '<' is a redirection operator, not a numeric comparison. The correct operator is '-lt'. Using '<' causes a syntax error.

🚀 Application

advanced

Script to categorize a number with if-elif-else

Which script correctly categorizes a number into 'small' (less than 5), 'medium' (5 to 10), or 'large' (greater than 10)?

A

#!/bin/bash
num=$1
if [ "$num" -lt 5 ]; then
  echo "small"
elif [ "$num" -le 10 ]; then
  echo "medium"
else
  echo "large"
fi

B

#!/bin/bash
num=$1
if [ "$num" -le 5 ]; then
  echo "small"
elif [ "$num" -lt 10 ]; then
  echo "medium"
else
  echo "large"
fi

C

#!/bin/bash
num=$1
if [ "$num" -lt 5 ]; then
  echo "small"
elif [ "$num" -lt 10 ]; then
  echo "medium"
else
  echo "large"
fi

D

#!/bin/bash
num=$1
if [ "$num" -lt 5 ]; then
  echo "small"
elif [ "$num" -gt 10 ]; then
  echo "medium"
else
  echo "large"
fi

💡 Hint

Check the numeric ranges carefully and the operators used.

Option A correctly uses '-lt 5' for small, '-le 10' for medium (including 5 to 10), and else for large. Others misclassify or overlap ranges.

🧠 Conceptual

advanced

Understanding else placement in if-elif-else

What happens if you omit the else block in an if-elif-else chain in Bash?

A The script runs but always executes the last elif block

B The script throws a syntax error

C The script runs without errors and does nothing if no conditions match

D The script runs but skips all conditions

💡 Hint

Think about what else does in a conditional chain.

The else block is optional. If omitted and no conditions match, the script simply skips the blocks and continues without error.

💻 Command Output

expert

Output of nested if-elif-else with multiple conditions

What is the output of this script when run with argument 0?

Bash Scripting

#!/bin/bash
num=$1
if [ "$num" -gt 0 ]; then
  if [ "$num" -lt 10 ]; then
    echo "Positive single digit"
  else
    echo "Positive double digit or more"
  fi
elif [ "$num" -eq 0 ]; then
  echo "Zero"
else
  echo "Negative number"
fi

A Zero

B Positive single digit

C Negative number

D Syntax error

💡 Hint

Trace the conditions carefully for input zero.

The script first checks if number is greater than zero (false for 0), then checks if number equals zero (true), so it prints 'Zero'.