Logical or Boolean expressions

Boolean expressions are also known as logical expressions.It is a combination of comparison expressions or matching expressions, using the Boolean operators together with parentheses to control nesting. There are three Booleanoperators, namely or ( ||) , and (&&), and not (!).The truth value ofBooleanexpression is calculated by combining the truth values of the component expressions.

Boolean expressions are usedto combine two or more conditional expressions.They return numeric value 1 if true and 0 if false.

Logical AND (&&): This operator is represented by the && symbol.Its syntax is:

expr1 && expr2

It evaluates to true if both expressions expr1 and expr2 evaluate to true; otherwise it returns false. Also expr2 is evaluated if and only if expr1 evaluates to true. For example, we print those records from the employee database emp.dat whose salary is greater than 2500 and gender is female:

$ awk '$5 == "F" && $7 > 2500 ...