Powershell in action

Windows PowerShell in Action

Licensed to Marco Tarantino

Licensed to Marco Tarantino

Windows PowerShell in Action

BRUCE PAYETTE

MANNING
Greenwich (74° w. long.)

Licensed to Marco Tarantino

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Copyeditor: Benjamin Berg Typesetter: Gordan Salinovic Cover designer: Leslie Haimes

ISBN 1932394-90-7 Printed in the United States of America 1 2 3 4 5 6 7 8 9 10 – MAL – 11 10 09 08 07

Licensed to Marco TarantinoTo my wife, Tina, for all her love and support

Licensed to Marco Tarantino

Licensed to Marco Tarantino

brief contents
Part 1 Learning PowerShell 1
1 Welcome to PowerShell 3 2 The basics 25 3 Working with types 55 4 Operators and expressions 87 115

5 Advanced operators and variables 6 Flow control in scripts 147

7 Functions and scripts 177 8 Scriptblocks and objects 214 9Errors, exceptions, and script debugging 251

Part 2

Using PowerShell 295
10 Processing text, files, and XML 297 11 Getting fancy—.NET and WinForms 12 Windows objects: COM and WMI 13 Security, security, security 440 344

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Licensed to Marco Tarantino

Licensed to Marco Tarantino

contents
foreword xv preface xvii acknowledgments xix about this book xx

Part 1LEARNING POWERSHELL 1
1 Welcome to PowerShell 3
1.1 What is PowerShell? 5 Shells, command-lines, and scripting languages 5 ✦ Why a new shell? Why now? 7 ✦ The last mile problem 7 1.2 Soul of a new language 8 Learning from history 8 ✦ Leveraging .NET 9 1.3 Brushing up on objects 10 Reviewing object-oriented programming 11 Objects in PowerShell 12 1.4 Dude! Where’s my code? 13 Installing and startingPowerShell 13 ✦ Command editing 15 Command completion 16 ✦ Evaluating basic expressions 17 Processing data 18 1.5 Summary 23

2 The basics 25
2.1 Command concepts and terminology 27 Commands and cmdlets 27 ✦ Command categories 30 Aliases and elastic syntax 34 2.2 Parsing and PowerShell 37 How PowerShell parses 37 ✦ Quoting 38 ✦ Expression mode and command mode parsing 41 ✦ Statement termination43

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Licensed to Marco Tarantino

2.3 Pipelines and commands 45 Pipelines and streaming behavior 46 Parameters and parameter binding 47 2.4 Formatting and output 48 The formatting cmdlets 49 ✦ The outputter cmdlets 51 2.5 Summary 54

3 Working with types 55
3.1 Type management in the wild, wild west 55 PowerShell: a type-promiscuous language 56 The type system and type adaptation 58 3.2Basic types and literals 60 Strings 60 ✦ Numbers and numeric literals 64 ✦ Collections: dictionaries and hashtables 66 ✦ Collections: arrays and sequences 71 ✦ Type literals 75 3.3 Type conversions 79 How type conversion works 79 ✦ PowerShell’s type-conversion algorithm 82 ✦ Special type conversions in parameter binding 85 3.4 Summary 86

4 Operators and expressions

87

4.1 Arithmetic...