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Learning AWK Programming

Learning AWK Programming

By : Kalkhanda
5 (4)
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Learning AWK Programming

Learning AWK Programming

5 (4)
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)
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Regular expression operators

When we use the == condition, AWK looks for an exact match. However, when we use the match operator (~), AWK looks for a partial match. Here, ~ means contains. To match a specific pattern using regular expression, ~ and !~ are used. Regular expression comparisons are performed using a matching expression built with either of these two operators. The right-hand side of the ~ or !~ operator could be a regular expression or string enclosed between forward slashes (/…/).

Match operator (~):

It is represented as a tilde (~) symbol. It matches a pattern in a specific field. Its syntax is as follows:

expression ~ /regexpr/

It matches if the string value of the expression contains a sub-string matched by regular expression regexpr.

For example, if you want to print the records containing Singh or Kapur in last name field from the employees database...

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