Arithmetics

Here we will learn how to perform arithmetic operations using shell scripts.

Arithmetics in Linux Shell Scripting

We use the keyword " expr " to perform arithmetic operations.

Syntax:
expr op1 math-operator op2

Example:

 
$ expr 3 + 2
$ expr 3 - 2
$ expr 10 / 2
$ expr 20 % 3
$ expr 10 \* 3
$ echo `expr 3 + 2`

In shell scripting we will be using the echo command to print the result of the arithmetic operations.

Note:
If you use echo command, before expr keyword we use ` (back quote) sign.
Here both double and single quote will not give you the desired result.
Try the following commands:

 
$ echo "expr 3 + 2" # Result expr 3 + 2
$ echo 'expr 3 + 2'  # Result expr 3 + 2
$ echo `expr 3 + 2` # Result 5

From the above example, we see that if we use double or single quote, the echo command directly prints " expr 3 + 2 ".
To get the result of this expression, we need to use the back quote.