Book Image

Learning AWK Programming

By : Shiwang Kalkhanda
5 (1)
Book Image

Learning AWK Programming

5 (1)
By: Shiwang Kalkhanda

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.
Table of Contents (11 chapters)

Working with Regular Expressions

AWK is a pattern-matching language. It searches for a pattern in a file and, upon finding the corresponding match, it performs the file's action on the input line. This pattern could consist of fixed strings or a pattern of text. This variable content or pattern is generally searched for with the help of regular expressions. Hence, regular expressions form a very important part of AWK programming language. In this chapter, we will look at regular expressions and how they are handled with AWK.

In this chapter, we will cover the following:

  • Regular expressions and their usage in AWK
  • The basic regular expression construct
  • Understanding the metacharacters of regular expression
  • The precedence of regular expressions
  • GAWK-specific regular expressions
  • Case-sensitive matching
  • Escape sequences