A logical condition is created, when two or more conditioned produce a single result based on them. Here one condition result may also invert the result of a other condition.
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. First condition is always checked but the second condition is checked only if first condition is returned falseAND is used between two or multiple conditions. It returns true only if all the conditions returns as true. First condition is always checked but the second condition is checked only if first condition is returned 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.
1 2 3 4 5 6 7 8 9 10 11 | #!/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.
1 2 3 4 5 6 7 8 9 10 11 | #!/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
Now, use the multiple logical operator in a single statement. Below example will help you to understand to how to use multiple logical operators in single statement.
1 2 3 4 5 6 7 8 9 10 | #!/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 |
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