Bash Script to Print Numbers 1 to n

Use a Bash for loop like for i in $(seq 1 $n); do echo $i; done to print numbers from 1 to n.

Examples

Input1

Output1

Input5

Output1 2 3 4 5

Input0

Output

How to Think About It

To print numbers from 1 to n, think of counting starting at 1 and going up to n. Use a loop that repeats for each number in this range and print each number on its own line.

Algorithm

1

Get the input number n.

2

Start a loop from 1 to n.

3

For each number in the loop, print the number.

4

End the loop after reaching n.

Code

bash

#!/bin/bash

read -p "Enter a number n: " n
for i in $(seq 1 $n)
do
  echo $i
done

Output

Enter a number n: 5
1
2
3
4
5

Dry Run

Let's trace input n=3 through the code

1

Read input

User inputs n=3

2

Start loop

Loop runs for i in 1 2 3

3

Print numbers

Print 1, then 2, then 3

i	Output
1	1
2	2
3	3

Why This Works

Step 1: Input reading

The script uses read to get the number n from the user.

Step 2: Looping through numbers

The for loop with seq 1 $n generates numbers from 1 to n.

Step 3: Printing each number

Inside the loop, echo $i prints the current number on its own line.

Alternative Approaches

Using while loop

bash

#!/bin/bash

read -p "Enter a number n: " n
count=1
while [ $count -le $n ]
do
  echo $count
  ((count++))
done

This uses a <code>while</code> loop and manual counter increment, which is more flexible but slightly longer.

Using brace expansion

bash

#!/bin/bash

read -p "Enter a number n: " n
for i in $(eval echo {1..$n})
do
  echo $i
done

Brace expansion <code>{1..n}</code> does not work with variables directly, so this method uses <code>eval</code> to expand the range.

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

Time Complexity

The loop runs from 1 to n, so it executes n times, making the time complexity O(n).

Space Complexity

The script uses constant extra space for variables and prints output directly, so space complexity is O(1).

Which Approach is Fastest?

Using for i in $(seq 1 $n) is simple and efficient; while loops add more lines but similar performance; brace expansion is limited with variables.

Approach	Time	Space	Best For
for loop with seq	O(n)	O(1)	Simple and readable for variable n
while loop	O(n)	O(1)	More control over loop conditions
brace expansion	O(n)	O(1)	Fixed ranges, not variable-friendly