Linux Shells by Example

7.7. Loops

Loops are used to repeatedly execute the statements following the test expression if a condition is true. Loops are often used to iterate through the fields within a record and to loop through the elements of an array in the END block. Awk has three types of loops: the while loop, the for loop, and the special for loop, which will be discussed later when working with awk arrays.

7.7.1. while Loop

The first step in using a while loop is to set a variable to an initial value. The value is then tested in the while expression. If the expression evaluates to true (nonzero), the body of the loop is entered and the statements within that body are executed. If there is more than one statement within the body of the loop, those statements ...