AWK Language Programming

by Arnold D. Robbins

AWK Language Programming

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A User's Guide for GNU AWK
Edition 1.0
January 1996

 

Arnold D. Robbins

Based on The GAWK Manual,
by Robbins, Close, Rubin, and Stallman

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To boldly go where no man has gone before" is a Registered Trademark of Paramount Pictures Corporation.

 

Copyright © 1989, 1991 - 1996 Free Software Foundation, Inc.

This is Edition 1.0 of AWK Language Programming,
for the 3.0 (or later) version of the GNU implementation of AWK.

Published by the Free Software Foundation
59 Temple Place — Suite 330
Boston, MA 02111-1307 USA
Phone: +1-617-542-5942
Fax (including Japan): +1-617-542-2652
Printed copies are available for $25 each.
ISBN 1-882114-26-4

Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies.

Permission is granted to copy and distribute modi ed versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one.

Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modi ed versions, except that this permission notice may be stated in a translation approved by the Foundation.

Cover art by Etienne Suvasa.

To Miriam, for making me complete.

To Chana, for the joy you bring us.

To Rivka, for the exponential increase.

Short Contents

Preface ....................................................................................................................................................................................................................................................

1

1

Introduction ....................................................................................................................................................................................................................................................

5

2

Getting Started with awk ....................................................................................................................................................................................................................................................

9

3

Useful One Line Programs ....................................................................................................................................................................................................................................................

21

4

Regular Expressions ....................................................................................................................................................................................................................................................

23

5

Reading Input Files ....................................................................................................................................................................................................................................................

37

6

Printing Output ....................................................................................................................................................................................................................................................

61

7

Expressions ....................................................................................................................................................................................................................................................

77

8

Patterns and Actions ....................................................................................................................................................................................................................................................

97

9

Control Statements in Actions ....................................................................................................................................................................................................................................................

105

10

Built-in Variables ....................................................................................................................................................................................................................................................

115

11

Arrays in awk ....................................................................................................................................................................................................................................................

123

12

Built-in Functions ....................................................................................................................................................................................................................................................

135

13

User-defined Functions ....................................................................................................................................................................................................................................................

153

14

Running awk ....................................................................................................................................................................................................................................................

161

15

A Library of awk Functions ....................................................................................................................................................................................................................................................

169

16

Practical awk Programs ....................................................................................................................................................................................................................................................

203

17

The Evolution of the awk Language ....................................................................................................................................................................................................................................................

251

Appendix A gawk Summary ....................................................................................................................................................................................................................................................

257

Appendix B Installing gawk ....................................................................................................................................................................................................................................................

277

Appendix C Implementation Notes ....................................................................................................................................................................................................................................................

293

Appendix D Glossary ....................................................................................................................................................................................................................................................

299

GNU GENERAL PUBLIC LICENSE ....................................................................................................................................................................................................................................................

307

Index ....................................................................................................................................................................................................................................................

315