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)

String constants

A string constant is a sequence of zero or more characters enclosed in double quotation marks. A string constant can be of any length, and they can have any of the possible 8-bit ASCII characters. These string constants can be stored in variables or appear literally as string constants, such as "River" or " ".

For example, if we want to print those records from cars.dat that contain the maruti string in the first field, we have to enclose the maruti string in double quotes while performing the match as follows:

$ awk '$1 == "maruti" {print}' cars.dat

The output of the execution of the preceding code is as follows:

maruti          swift       2007        50000       5
maruti dezire 2009 3100 6
maruti swift 2009 4100 5
maruti esteem 1997 98000 ...