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)

Arithmetic expressions using binary operators

AWK supports almost all basic arithmetic operators for building arithmetic expressions. These operators are binary operators; that is, they operate on two variables and are very similar to C language expressions. All these arithmetic operators follow the normal precedence rule. AWK supports the following arithmetic operators.

Addition (p + q):

This is represented by a plus (+) symbol, which adds two or more numbers. These numbers could be variables or constants. For example, we can add two numbers after assigning them to two variables as follows:

$ awk 'BEGIN{ p = 20; q = 30; print "( p + q ) = ",( p + q )}'

The output on execution of this code is as follows:

( p + q ) =  50

Now, we will use the marks.txt sample file to calculate the sum of marks obtained by a student using the arithmetic operator, as follows: