Bash How to Add Numbers

September 8, 2021 by Raju

Bash provides a lot of methods how to add numbers. First of all is use $(())

echo $((2+2+1))

Output: 5

If we have a variable which has an integer value, we can use “$var”:

var=5
echo $((6+$var))

Output: 11

We can assign to variable counted numbers:

var=$((3+6))

The value of “var” is 9 now.

Another arithmetic expansion:
var=$((num1 + num2))
var=$(($num + $num2))
var=$((num1 + 10 + 20))
var=$[num1+num2]