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)

The print statement

So far, we have been using print statements mainly to produce simple yet standardized output. With a print statement, we specify the expressions to print as a list separated by commas. The output is separated by single spaces, followed by a newline. The print statement has two forms:

print expr1, expr2, ……, exprn
print (expr1, expr2, ………, exprn)

Both print the string value of each expression separated by the Output Field Separator (OFS); the default is a single space followed by the Output Record Separator (ORS); the default is newline. Using parentheses is necessary if an expression uses the > relational operator to mark its differentiation from redirection operator. Here expression could be any AWK expression or any constant string, or number, or field of current input record (like $1, $2, ... and so on). Numeric values...