UNIX® Shells by Example, Third Edition

7.1. Variables

7.1.1. Numeric and String Constants

Numeric constants can be represented as integers, such as 243, floating point numbers, such as 3.14, or numbers using scientific notation, such as .723E-1 or 3.4e7. Strings, such as Hello world, are enclosed in double quotes.

Initialization and Type Coercion. Just mentioning a variable in your awk program causes it to exist. A variable can be a string, a number, or both. When it is set, it becomes the type of the expression on the right-hand side of the equal sign.

Uninitialized variables have the value zero or the value " ", depending on the context in which they are used.

name = "Nancy" name is a string

x++            x
						is a number;
						x
						is initialized to zero and incremented by 1

number = 35    number is ...