Book Image

Learning AWK Programming

By : Kalkhanda
5 (1)
Book Image

Learning AWK Programming

5 (1)
By: 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 AWK

Like other programming environments, AWK also has environment variables. In this section, we will discuss the different environment variables available to users in the AWK programming language.

ARGC and ARGV

The ARGC and ARGV variables are used to pass arguments to the AWK script from the command line.

ARGC specifies the total number of arguments passed to the AWK script on the command line. It always has a value of 1 or more, as it counts the program name as the first argument.

The AWK script filename specified using the -f option is not counted as an argument. If we declare any variable on the command line, it is counted as an argument in GAWK:

$ awk 'BEGIN { print "No of arguments...