How to Use Logical OR & AND in Shell Script with Examples

Logical OR & AND operations are very useful where multiple conditions are used in our programs (scripts).

• OR is used between two or multiple conditions. It returns true if any one of conditions returns as true.
• AND is used between two or multiple conditions. It returns true only if all the conditions returns as true.

Using Logical OR

Logical OR in bash script is used with operator -o. Below small shell script will show you to how to use logical OR ( -o ) between two conditions.

#!/bin/bash

read -p "Enter First Numeric Value: "   first
read -p "Enter Second Numeric Value: "  second


if [ $first -le 10  -o  $second -gt 20 ]
then
        echo "OK"
else
	echo "Not OK"
fi

Using Logical AND

Logical AND in bash script is used with operator -a. Below shell script will show you to how to use logical AND ( -a ) between two conditions.

#!/bin/bash

read -p "Enter First Numeric Value: "   first
read -p "Enter Second Numeric Value: "  second


if [ $first -le 10  -a  $second -gt 20 ]
then
        echo "OK"
else
	echo "Not OK"
fi

Using Multiple Logical OR & AND

Below example will help you to understand to how to use multiple logical operators in single statement.

#!/bin/bash

read -p "Enter Your Number:"  i


if [ ( $i -ge 10  -a  $i -le 20 ) -o ( $i -ge 100  -a  $i -le 200 ) ]
then
        echo "OK"
else
	echo "Not OK"
fi