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Linux Shells by Example by Ellie Quigley

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7.1. Variables

7.1.1. Numeric and String Constants

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

Initialialization 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 a number ...

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