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)

GAWK-specific regular expression operators

GAWK has some more regular expression operators, in addition to those we've already discussed. The operators described in this section are specific to GAWK and are not available in other AWK implementations. These are basically shorthand character classes that are frequently used, and most of them deal with word matching (here, word refers to a sequence of one or more letters, digits, or underscores). We access them by using the escape character, '\', followed by a letter (here, the escape character adds special meaning to them instead of taking it away).

Let's create a file to practice GAWK-only operators:

vi  gopr.txt
start end
white space example
e d
white space example with tab
e d