This chapter will focus on the usage of AWK variables. By the end of the chapter, the reader will understand how to use built-in and user-defined variables while writing AWK programs and command lines. Almost all expressions contain variables. Some of the variables are user-defined, while some are built-in, and others are fields. A variable is a named location that is either a string or a number, or both. User-defined variables in AWK consist of sequences of alphanumeric characters and underscores, with the exception that they do not begin with a digit. All built-in variables have uppercase names. The AWK variable type is not declared, but automatically infers the type from the context. When required, AWK converts a string value to a numeric value and vice versa. This chapter will give you a deep insight into different built-in and environment variables...
Learning AWK Programming
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Learning AWK Programming
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Overview of this book
AWK is one of the most primitive and powerful utilities which exists in all Unix and Unix-like distributions. It is used as a command-line utility when performing a basic text-processing operation, and as programming language when dealing with complex text-processing and mining tasks. With this book, you will have the required expertise to practice advanced AWK programming in real-life examples.
The book starts off with an introduction to AWK essentials. You will then be introduced to regular expressions, AWK variables and constants, arrays and AWK functions and more. The book then delves deeper into more complex tasks, such as printing formatted output in AWK, control flow statements, GNU's implementation of AWK covering the advanced features of GNU AWK, such as network communication, debugging, and inter-process communication in the GAWK programming language which is not easily possible with AWK.
By the end of this book, the reader will have worked on the practical implementation of text processing and pattern matching using AWK to perform routine tasks.
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Current Title:
Learning AWK Programming
Table of Contents (11 chapters)
Preface
Free Chapter
Getting Started with AWK Programming
Working with Regular Expressions
AWK Variables and Constants
Working with Arrays in AWK
Printing Output in AWK
AWK Expressions
AWK Control Flow Statements
AWK Functions
GNU's Implementation of AWK – GAWK (GNU AWK)
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