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)

Environment variables in GAWK

In this section, we discuss the various GAWK-specific variables. They are not available in the original AWK distribution. However, on modern Linux systems, generally these options will work because AWK is set as a symbolic link to the GAWK executable.

ARGIND

ARGIND represents the index in the ARGV array to retrieve the current file being processed. When we operate with one file in AWK script, the ARGIND will be 1, and ARGV[ARGIND] will return the filename that is currently being processed.

In the following example, we print the value of ARGIND and the current filename using ARGV[ARGIND] as follows:

$ vi argind.awk

END {
print "ARGIND : ", ARGIND;
print "Current Filename...