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)

Referring to members in arrays

We can directly display the value stored in an array element using the print command, or we can assign it to another variable for further processing inside a AWK program as follows:

$ vi arr_var_assign.awk

BEGIN {
arr[10] = "maruti"
arr[20] = "audi"
print "arr[10] : " arr[10]
x=arr[20] print "x : " x
}

$ awk -f arr_var_assign.awk

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

arr[10] : maruti
x : audi

To check whether a particular index exists in an array, we use the if condition within the operator to build the conditional expression syntax, as shown in the following syntactical phrase. It will return true (1), if the index exists in the array; otherwise, it will return false (0):

if(index in array)

In the following example, we show you how the if condition works when...