Classic Shell Scripting

by Robbins, Arnold

• ISBN13: 9780596005955
• ISBN10: 0596005954
• Format: Paperback
• Copyright: 2005-06-01
• Publisher: Oreilly & Associates Inc

Summary

Writing shell scripts requires more than just a knowledge of the shell language, it also requires familiarity with the individual Unix programs: why each one is there, how to use them by themselves, and in combination with the other programs. The authors are intimately familiar with the tips and tricks that can be used to create excellent scripts, as well as the traps that can make your best effort a bad shell script. With Classic Shell Scripting you'll avoid hours of wasted effort. You'll learn not only write useful shell scripts, but how to do it properly and portably. The ability to program and customize the shell quickly, reliably, and portably to get the best out of any individual system is an important skill for anyone operating and maintaining Unix or Linux systems. Classic Shell Scripting gives you everything you need to master these essential skills

Author Biography

Arnold Robbins, an Atlanta native, is a professional programmer and technical author. He has worked with Unix systems since 1980, when he was introduced to a PDP-11 running a version of Sixth Edition Unix. He has been a heavy AWK user since 1987, when he became involved with gawk, the GNU project's version of AWK. As a member of the POSIX 1003.2 balloting group, he helped shape the POSIX standard for AWK. He is currently the maintainer of gawk and its documentation. He is also coauthor of the sixth edition of O'Reilly's Learning the vi Editor. Since late 1997, he and his family have been living happily in Israel.

Nelson Beebe is a long time Unix user and system administrator, and has helped for years on Usenet newsgroups.

Table of Contents

Foreword	p. ix
Preface	p. xi
Background	p. 1
Unix History	p. 1
Software Tools Principles	p. 4
Summary	p. 6
Getting Started	p. 8
Scripting Languages Versus Compiled Languages	p. 8
Why Use a Shell Script?	p. 9
A Simple Script	p. 9
Self-Contained Scripts: The #! First Line	p. 10
Basic Shell Constructs	p. 12
Accessing Shell Script Arguments	p. 23
Simple Execution Tracing	p. 24
Internationalization and Localization	p. 25
Summary	p. 28
Searching and Substitutions	p. 30
Searching for Text	p. 30
Regular Expressions	p. 31
Working with Fields	p. 56
Summary	p. 65
Text Processing Tools	p. 67
Sorting Text	p. 67
Removing Duplicates	p. 75
Reformatting Paragraphs	p. 76
Counting Lines, Words, and Characters	p. 77
Printing	p. 78
Extracting the First and Last Lines	p. 83
Summary	p. 86
Pipelines Can Do Amazing Things	p. 87
Extracting Data from Structured Text Files	p. 87
Structured Data for the Web	p. 94
Cheating at Word Puzzles	p. 100
Word Lists	p. 102
Tag Lists	p. 105
Summary	p. 107
Variables, Making Decisions, and Repeating Actions	p. 109
Variables and Arithmetic	p. 109
Exit Statuses	p. 120
The case Statement	p. 129
Looping	p. 130
Functions	p. 135
Summary	p. 138
Input and Output, Files, and Command Evaluation	p. 140
Standard Input, Output, and Error	p. 140
Reading Lines with read	p. 140
More About Redirections	p. 143
The Full Story on printf	p. 147
Tilde Expansion and Wildcards	p. 152
Command Substitution	p. 155
Quoting	p. 161
Evaluation Order and eval	p. 162
Built-in Commands	p. 168
Summary	p. 175
Production Scripts	p. 177
Path Searching	p. 177
Automating Software Builds	p. 192
Summary	p. 222
Enough awk to Be Dangerous	p. 223
The awk Command Line	p. 224
The awk Programming Model	p. 225
Program Elements	p. 226
Records and Fields	p. 236
Patterns and Actions	p. 238
One-Line Programs in awk	p. 240
Statements	p. 244
User-Defined Functions	p. 252
String Functions	p. 255
Numeric Functions	p. 264
Summary	p. 266
Working with Files	p. 267
Listing Files	p. 267
Updating Modification Times with touch	p. 273
Creating and Using Temporary Files	p. 274
Finding Files	p. 279
Running Commands: xargs	p. 293
Filesystem Space Information	p. 295
Comparing Files	p. 299
Summary	p. 307
Extend Example: Merging User Databases	p. 308
The Problem	p. 308
The Password Files	p. 309
Merging Password Files	p. 310
Changing File Ownership	p. 317
Other Real-World Issues	p. 321
Summary	p. 323
Spellchecking	p. 325
The spell Program	p. 325
The Original Unix Spellchecking Prototype	p. 326
Improving ispell and aspell	p. 327
A Spellchecker in awk	p. 331
Summary	p. 350
Processes	p. 352
Process Creation	p. 353
Process Listing	p. 354
Process Control and Deletion	p. 360
Process System-Call Tracing	p. 368
Process Accounting	p. 372
Delayed Scheduling of Processes	p. 373
The /proc Filesystem	p. 378
Summary	p. 379
Shell Portability Issues and Extensions	p. 381
Gotchas	p. 381
The bash shopt Command	p. 385
Common Extensions	p. 389
Download Information	p. 402
Other Extended Bourne-Style Shells	p. 405
Shell Versions	p. 405
Shell Initialization and Termination	p. 406
Summary	p. 412
Secure Shell Scripts: Getting Started	p. 413
Tips for Secure Shell Scripts	p. 413
Restricted Shell	p. 416
Trojan Horses	p. 418
Setuid Shell Scripts: A Bad Idea	p. 419
ksh93 and Privileged Mode	p. 421
Summary	p. 422
Writing Manual Pages	p. 423
Files and Filesystems	p. 437
Important Unix Commands	p. 473
Bibliography	p. 478
Glossary	p. 484
Index	p. 509
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