In ksh and bash, the shell enable integer arithmetic to be to be performed.This avoids having to run an extra program such as expr or bc to do math in a shell script
Syntax: Var=$((expression))
Example:
$ foo=$((((2+6*3)-5)/3))
$ echo $foo
5
The operators which can be used in the arithmetic substitution.
Operators Description
/ The division Operator divides two numbers and return the result.
* The multiplication operator multiplies two numbers and return the result.
– The subtraction operator subtracts two numbers and returns the difference.
+ The addition operator adds two numbers and returns the result.
() The parentheses is used to clarify which expression should be evaluated first.