Bash Script to Find Sum of n Numbers

Use a Bash script that reads n numbers in a loop and adds them using a variable, like sum=0; for ((i=0; i.

Examples

Input3 1 2 3

Output6

Input5 10 20 30 40 50

Output150

Input0

Output0

How to Think About It

To find the sum of n numbers, first get how many numbers you want to add. Then read each number one by one, keep adding it to a total sum. Finally, show the total sum after all numbers are added.

Algorithm

1

Get the number n from the user.

2

Set a variable sum to 0.

3

Repeat n times: read a number and add it to sum.

4

After the loop, print the sum.

Code

bash

#!/bin/bash
read -p "Enter count of numbers: " n
sum=0
for ((i=0; i<n; i++))
do
  read -p "Enter number $((i+1)): " num
  sum=$((sum + num))
done
echo "Sum of $n numbers is: $sum"

Output

Enter count of numbers: 3
Enter number 1: 4
Enter number 2: 5
Enter number 3: 6
Sum of 3 numbers is: 15

Dry Run

Let's trace the input 3 numbers: 4, 5, 6 through the code

1

Read n

User inputs n=3

2

Initialize sum

sum=0

3

Loop iteration 1

Read num=4; sum=0+4=4

4

Loop iteration 2

Read num=5; sum=4+5=9

5

Loop iteration 3

Read num=6; sum=9+6=15

6

Print sum

Output: Sum of 3 numbers is: 15

Iteration	Input Number	Sum After Addition
1	4	4
2	5	9
3	6	15

Why This Works

Step 1: Reading the count

We use read to get how many numbers the user wants to add.

Step 2: Adding numbers in a loop

The for loop runs n times, each time reading a number and adding it to sum using $((sum + num)).

Step 3: Displaying the result

After the loop, echo prints the total sum to the screen.

Alternative Approaches

Using while loop

bash

#!/bin/bash
read -p "Enter count of numbers: " n
sum=0
count=0
while [ $count -lt $n ]
do
  read -p "Enter number $((count+1)): " num
  sum=$((sum + num))
  count=$((count + 1))
done
echo "Sum is: $sum"

This uses a while loop instead of for; both are equally readable but while is more flexible for unknown counts.

Sum from command line arguments

bash

#!/bin/bash
sum=0
for num in "$@"
do
  sum=$((sum + num))
done
echo "Sum is: $sum"

This sums numbers passed as arguments when running the script, no interactive input needed.

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

Time Complexity

The script reads and adds each of the n numbers once, so time grows linearly with n.

Space Complexity

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

Which Approach is Fastest?

All approaches run in O(n) time; using command line arguments avoids input prompts but requires all numbers upfront.

Approach	Time	Space	Best For
For loop with read	O(n)	O(1)	Interactive input with known count
While loop with read	O(n)	O(1)	Flexible looping with interactive input
Command line arguments	O(n)	O(1)	Non-interactive, batch input