Bash Script to Find Power of a Number

Use a Bash script with a loop to multiply the base number by itself exponent times, like: result=1; for ((i=0; i.

Examples

Inputbase=2, exponent=3

Output8

Inputbase=5, exponent=0

Output1

Inputbase=3, exponent=4

Output81

How to Think About It

To find the power of a number, multiply the base by itself repeatedly as many times as the exponent says. Start with 1 because multiplying by 1 doesn't change the value. Then multiply the result by the base in each step until you reach the exponent count.

Algorithm

1

Get the base number and exponent from the user.

2

Initialize a result variable to 1.

3

Repeat multiplying the result by the base, exponent times.

4

After the loop, output the result.

Code

bash

#!/bin/bash
read -p "Enter base number: " base
read -p "Enter exponent: " exponent
result=1
for ((i=0; i<exponent; i++))
do
  result=$((result * base))
done
echo "$base raised to the power $exponent is $result"

Output

Enter base number: 2
Enter exponent: 3
2 raised to the power 3 is 8

Dry Run

Let's trace base=2 and exponent=3 through the code

1

Initialize result

result = 1

2

First loop iteration

result = 1 * 2 = 2

3

Second loop iteration

result = 2 * 2 = 4

4

Third loop iteration

result = 4 * 2 = 8

Iteration	Result
0 (initial)	1
1	2
2	4
3	8

Why This Works

Step 1: Start with 1

We set result=1 because multiplying by 1 keeps the value unchanged, serving as a neutral starting point.

Step 2: Multiply in loop

Each loop multiplies result by base, repeating this exponent times to build the power.

Step 3: Output final result

After the loop finishes, result holds the base raised to the exponent, which we print.

Alternative Approaches

Using bc command

bash

#!/bin/bash
read -p "Enter base number: " base
read -p "Enter exponent: " exponent
result=$(echo "$base^$exponent" | bc)
echo "$base raised to the power $exponent is $result"

This uses the external bc calculator for power, which handles large numbers and decimals but requires bc installed.

Using arithmetic expansion with ** operator (bash 4+)

bash

#!/bin/bash
read -p "Enter base number: " base
read -p "Enter exponent: " exponent
result=$((base ** exponent))
echo "$base raised to the power $exponent is $result"

This uses Bash's built-in exponent operator, which is simpler but requires Bash version 4 or higher.

Complexity: O(n) time, O(1) space

Time Complexity

The loop runs exponent times, so the time grows linearly with the exponent.

Space Complexity

Only a few variables are used, so space is constant regardless of input size.

Which Approach is Fastest?

Using Bash's ** operator is fastest and simplest, while the loop method is more manual but compatible with older Bash versions.

Approach	Time	Space	Best For
Loop multiplication	O(n)	O(1)	Compatibility with all Bash versions
bc command	Depends on bc	O(1)	Handling large or decimal powers
Bash ** operator	O(1)	O(1)	Simple integer powers with modern Bash