Windows Powershell in Action, 2nd Edition potx

MANNING
Bruce Payette
SECOND EDITION
Covers PowerShell v2
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PRAISE FOR THE FIRST EDITION
The book on PowerShell, it has all the secrets.
—James Truher, PowerShell Program Manager, Microsoft
If all it had going for it was the authoritative pedigree of the writer, it might be worth it, but it’s also
well-written, well-organized, and thorough, which I think makes it invaluable as both a learning tool
and a reference.
—Slashdot.org
an encyclopedic tome of PowerShell scripting bringing the reader through the basics with simple shell
scripts through powerful and flexible scripts any Windows systems administrator will find immediately
useful.
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The nuances of PowerShell from the lead language designer himself! Excellent content and easy read-
ability!
—Keith Hill, Software Architect
[It gives you] inside information, excellent examples, and a colorful writing style.
—Marc van Orsouw (MOW), PowerShell MVP
There’s no better way to learn PowerShell than from someone on the core PowerShell team—and that’s
exactly what you get with this book.
—Joe Topjian, adminspotting.net
Where’s the 6 stars option? I haven’t enjoyed a software engineering book to the same extent for a long
time.
—T. Kirby Green, Technical Architect, SunGard
Consider this book the definitive reference for PowerShell. As one of the designers of the PowerShell
environment, the author knows all the ins and outs, back alleys, hidden rooms, and secret handshakes
the language offers, and isn’t afraid to grab you by the hand and drag you along (like it or not!) for the
tour of your life.

—Jase T. Wolfe, Amazon reader
I love this book!
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Windows PowerShell
in Action, Second Edition
BRUCE PAYETTE
MANNING
Shelter Island
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v
brief contents
Part 1 Learning PowerShell 1
1 Welcome to PowerShell 3
2 Foundations of PowerShell 36
3 Working with types 72
4 Operators and expressions 110
5 Advanced operators and variables 151
6 Flow control in scripts 198
7 PowerShell functions 236
8 Advanced functions and scripts 275
9 Using and authoring modules 322
10 Module manifests and metadata 361
11 Metaprogramming with scriptblocks and dynamic code 392
12 Remoting and background jobs 447
13 Remoting: configuring applications and services 502
14 Errors and exceptions 553
15 The PowerShell ISE and debugger 606
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vi BRIEF CONTENTS
Part 2 Using PowerShell 661

16 Working with files, text, and XML 663
17 Extending your reach with .NET 719
18 Working with COM 760
19 Management objects: WMI and WS-MAN 797
20 Responding in real time with eventing 847
21 Security, security, security 888
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vii
contents
preface xix
acknowledgments xxi
about this book xxiii
about the cover illustration xxix
Part 1 Learning PowerShell 1
1 Welcome to PowerShell 3
1.1 What is PowerShell? 5
Shells, command lines, and scripting languages 6 ✦ Why a new
shell? Why now? 7 ✦ The last mile problem 8
1.2 Soul of a new language 9
Learning from history 9 ✦ Leveraging .NET 10
1.3 Brushing up on objects 11
Reviewing object-oriented programming 11 ✦ Objects in
PowerShell 13
1.4 Up and running with PowerShell 13
PowerShell 14 ✦ Starting PowerShell 14 ✦ The PowerShell
console host 14 ✦ The PowerShell Integrated Scripting
Environment 17 ✦ Command completion 20
1.5 Dude! Where’s my code? 22
Navigation and basic operations 22 ✦ Basic expressions and
variables 23 ✦ Processing data 25 ✦ Flow control

statements 30 ✦ Scripts and functions 31 ✦ Remoting and
the Universal Execution Model 32
1.6 Summary 35
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viii CONTENTS
2 Foundations of PowerShell 36
2.1 Getting a sense of the PowerShell language 37
2.2 The core concepts 38
Command concepts and terminology 38 ✦ Commands and
cmdlets 38 ✦ Command categories 42
2.3 Aliases and elastic syntax 46
2.4 Parsing and PowerShell 50
How PowerShell parses 51 ✦ Quoting 51 ✦ Expression-
mode and command-mode parsing 54 ✦ Statement
termination 56 ✦ Comment syntax in PowerShell 58
2.5 How the pipeline works 60
Pipelines and streaming behavior 61 ✦ Parameters and
parameter binding 62
2.6 Formatting and output 64
The formatting cmdlets 64 ✦ The outputter cmdlets 67
2.7 Summary 70
3 Working with types 72
3.1 Type management in the wild, wild West 72
PowerShell: a type-promiscuous language 73 ✦ The type
system and type adaptation 75
3.2 Basic types and literals 77
String literals 77 ✦ Numbers and numeric literals 82
3.3 Collections: dictionaries and hash tables 85
Creating and inspecting hash tables 85 ✦ Modifying and
manipulating hash tables 88 ✦ Hash tables as reference

types 90
3.4 Collections: arrays and sequences 91
Collecting pipeline output as an array 91 ✦ Array
indexing 92 ✦ Polymorphism in arrays 92 ✦ Arrays as
reference types 93 ✦ Singleton arrays and empty arrays 94
3.5 Type literals 96
Type name aliases 96 ✦ Generic type literals 98 ✦ Accessing
static members with type literals 99
3.6 Type conversions 101
How type conversion works 101 ✦ PowerShell’s type-
conversion algorithm 104 ✦ Special type conversions in
parameter binding 107
3.7 Summary 109
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CONTENTS ix
4 Operators and expressions 110
4.1 Arithmetic operators 112
The addition operator 113 ✦ The multiplication operator 116
Subtraction, division, and the modulus operator 117
4.2 The assignment operators 119
Multiple assignments 120 ✦ Multiple assignments with type
qualifiers 121 ✦ Assignment operations as
value expressions 123
4.3 Comparison operators 124
Scalar comparisons 125 ✦ Comparisons and case
sensitivity 127 ✦ Using comparison operators
with collections 129
4.4 Pattern matching and text manipulation 131
Wildcard patterns and the -like operator 132 ✦ Regular
expressions 133 ✦ The -match operator 134 ✦ The -replace

operator 137 ✦ The -join operator 139 ✦ The -split
operator 143
4.5 Logical and bitwise operators 148
4.6 Summary 150
5 Advanced operators and variables 151
5.1 Operators for working with types 152
5.2 The unary operators 154
5.3 Grouping and subexpressions 157
Subexpressions $( ) 159 ✦ Array subexpressions @( ) 160
5.4 Array operators 162
The comma operator 162 ✦ The range operator 165
Array indexing and slicing 167 ✦ Using the range
operator with arrays 170 ✦ Working with
multidimensional arrays 171
5.5 Property and method operators 173
The dot operator 174 ✦ Static methods and the double-colon
operator 177 ✦ Indirect method invocation 178
5.6 The format operator 179
5.7 Redirection and the redirection operators 181
5.8 Working with variables 184
Creating variables 185 ✦ Variable name syntax 186
Working with the variable cmdlets 188
Splatting a variable 193
5.9 Summary 196
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x CONTENTS
6 Flow control in scripts 198
6.1 The conditional statement 200
6.2 Looping statements 203
The while loop 203 ✦ The do-while loop 204 ✦ The for

loop 205 ✦ The foreach loop 207
6.3 Labels, break, and continue 212
6.4 The switch statement 215
Basic use of the switch statement 215 ✦ Using wildcard
patterns with the switch statement 216 ✦ Using regular
expressions with the switch statement 217 ✦ Processing files
with the switch statement 221 ✦ Using the $switch loop
enumerator in the switch statement 222
6.5 Flow control using cmdlets 223
The ForEach-Object cmdlet 223 ✦ The Where-Object
cmdlet 228
6.6 Statements as values 231
6.7 A word about performance 233
6.8 Summary 234
7 PowerShell functions 236
7.1 Fundamentals of PowerShell functions 237
Passing arguments using $args 237 ✦ Example functions:
ql and qs 239 ✦ Simplifying $args processing with multiple
assignment 240
7.2 Declaring formal parameters for a function 241
Mixing named and positional parameters 242 ✦ Adding type
constraints to parameters 243 ✦ Handling variable numbers of
arguments 245 ✦ Initializing function parameters with default
values 246 ✦ Handling mandatory parameters, v1-style 248
Using switch parameters to define command switches 248
Switch parameters vs. Boolean parameters 252
7.3 Returning values from functions 257
Debugging problems in function output 259 ✦ The return
statement 262
7.4 Using simple functions in a pipeline 263

Filters and functions 265 ✦ Functions with begin, process, and
end blocks 266
7.5 Managing function definitions in a session 267
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7.6 Variable scoping in functions 269
Declaring variables 270 ✦ Using variable scope modifiers 272
7.7 Summary 273
8 Advanced functions and scripts 275
8.1 PowerShell scripts 276
Script execution policy 276 ✦ Passing arguments to
scripts 278 ✦ Exiting scripts and the exit statement 280
Scopes and scripts 281 ✦ Managing your scripts 284
Running PowerShell scripts from other applications 285
8.2 Writing advanced functions and scripts 287
Specifying script and function attributes 288 ✦ The
CmdletBinding attribute 289 ✦ The OutputType
attribute 293 ✦ Specifying parameter attributes 296
Creating parameter aliases with the Alias attribute 303
Parameter validation attributes 305
8.3 Dynamic parameters and dynamicParam 311
Steps for adding a dynamic parameter 312 ✦ When should
dynamic parameters be used? 314
8.4 Documenting functions and scripts 314
Automatically generated help fields 315 ✦ Creating manual help
content 315 ✦ Comment-based help 316 ✦ Tags used in
documentation comments 318
8.5 Summary 321
9 Using and authoring modules 322
9.1 The role of a module system 323

Module roles in PowerShell 324 ✦ Module mashups: composing
an application 324
9.2 Module basics 325
Module terminology 326 ✦ Modules are single-instance
objects 326
9.3 Working with modules 327
Finding modules on the system 327 ✦ Loading a module 331
Removing a loaded module 335
9.4 Writing script modules 337
A quick review of scripts 338 ✦ Turning a script into a
module 340 ✦ Controlling member visibility with Export-
ModuleMember 343 ✦ Installing a module 347 ✦ How
scopes work in script modules 348 ✦ Nested modules 350
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xii CONTENTS
9.5 Binary modules 353
Binary modules versus snap-ins 354 ✦ Creating a binary
module 355 ✦ Nesting binary modules in script modules 357
9.6 Summary 360
10 Module manifests and metadata 361
10.1 Module folder structure 362
10.2 Module manifest structure 363
10.3 Production manifest elements 366
Module identity 368 ✦ Runtime dependencies 368
10.4 Construction manifest elements 370
The loader manifest elements 371 ✦ Module component
load order 374
10.5 Content manifest elements 375
10.6 Language restrictions in a manifest 376
10.7 Advanced module operations 378

The PSModuleInfo object 378 ✦ Using the PSModuleInfo
methods 382 ✦ The defining module versus the calling
module 384 ✦ Setting module properties from inside a script
module 388 ✦ Controlling when modules can be unloaded 388
Running an action when a module is removed 389
10.8 Summary 390
11 Metaprogramming with scriptblocks and dynamic code 392
11.1 Scriptblock basics 393
Invoking commands 394 ✦ The scriptblock literal 397
Defining functions at runtime 398
11.2 Building and manipulating objects 400
Looking at members 400 ✦ Using Add-Member to
extend objects 402 ✦ Adding note properties with
New-Object 409
11.3 Using the Select-Object cmdlet 410
11.4 Dynamic modules 412
Dynamic script modules 412 ✦ Closures in PowerShell 414
Creating custom objects from modules 417
11.5 Steppable pipelines 418
How steppable pipelines work 418 ✦ Creating a proxy command
with steppable pipelines 420
11.6 A closer look at the type-system plumbing 423
Adding a property 425 ✦ Shadowing an existing
property 427
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CONTENTS xiii
11.7 Extending the PowerShell language 428
Little languages 428 ✦ Adding a CustomClass keyword to
PowerShell 428 ✦ Type extension 433
11.8 Building script code at runtime 436

The Invoke-Expression cmdlet 436 ✦ The ExecutionContext
variable 437 ✦ The ExpandString() method 437 ✦ The
InvokeScript() method 438 ✦ Mechanisms for creating
scriptblocks 438 ✦ Creating functions using the function:
drive 439
11.9 Compiling code with Add-Type 440
Defining a new .NET class: C# 440 ✦ Defining a new enum at
runtime 442 ✦ Dynamic binary modules 443
11.10 Summary 445
12 Remoting and background jobs 447
12.1 Getting started with remoting 448
Commands with built-in remoting 448 ✦ The PowerShell
remoting subsystem 449 ✦ Enabling remoting 450
Additional setup steps for workgroup environments 451
Enabling remoting in the enterprise 452
12.2 Applying PowerShell remoting 454
Basic remoting examples 454 ✦ Adding concurrency to the
examples 455 ✦ Solving a real problem: multimachine
monitoring 457
12.3 Sessions and persistent connections 462
Additional session attributes 466 ✦ Using the New-PSSession
cmdlet 468 ✦ Interactive sessions 469 ✦ Managing
PowerShell sessions 472
12.4 Implicit remoting 473
Using implicit remoting 474 ✦ How implicit remoting
works 476
12.5 Background jobs in PowerShell 481
The job commands 483 ✦ Working with the job cmdlets 483
Working with multiple jobs 487 ✦ Starting jobs on remote
computers 489 ✦ Running jobs in existing sessions 492

12.6 Considerations when running commands remotely 493
Remote session startup directory 494 ✦ Profiles and
remoting 494 ✦ Issues running executables remotely 495
Reading and writing to the console 496 ✦ Remote output vs. local
output 497 ✦ Processor architecture issues 498
12.7 Summary 500
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xiv CONTENTS
13 Remoting: configuring applications and services 502
13.1 Remoting infrastructure in depth 503
The PowerShell remoting protocol stack 503 ✦ Using the
WSMan cmdlets and providers 509 ✦ Authenticating the target
computer 511 ✦ Authenticating the connecting user 514
Addressing the remoting target 518 ✦ Windows version-specific
connection issues 520 ✦ Managing resource consumption 522
13.2 Building custom remoting services 527
Remote service connection patterns 527 ✦ Working with custom
configurations 530 ✦ Creating a custom configuration 531
Access controls and endpoints 533 ✦ Constraining a PowerShell
session 535 ✦ Creating a constrained execution environment 543
13.3 Summary 551
14 Errors and exceptions 553
14.1 Error handling 554
ErrorRecords and the error stream 555 ✦ The $error variable and
–ErrorVariable parameter 560 ✦ Determining if a command had
an error 564 ✦ Controlling the actions taken on an error 566
14.2 Dealing with errors that terminate execution 569
The trap statement 570 ✦ The try/catch/finally statement 575
The throw statement 578
14.3 Debugging with the host APIs 580

Catching errors with strict mode 582 ✦ The Set-StrictMode
cmdlet in PowerShell v2 584 ✦ Static analysis of scripts 589
14.4 Capturing session output 593
Starting the transcript 593 ✦ What gets captured in the
transcript 595
14.5 PowerShell and the event log 597
The EventLog cmdlets 597 ✦ Examining the PowerShell
event log 603
14.6 Summary 605
15 The PowerShell ISE and debugger 606
15.1 The PowerShell ISE 607
Controlling the ISE pane layout 607 ✦ Using the ISE
editor 610 ✦ Executing commands in the ISE 614
Considerations when running scripts in the ISE 616
15.2 Using multiple PowerShell tabs 618
Local in-memory session tabs 619 ✦ Remote session tabs in
PowerShell ISE 619
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CONTENTS xv
15.3 Extending the ISE 622
The $psISE variable 622 ✦ Using the Options property 624
Managing tabs and files 625 ✦ Working with text panes 629
Adding a custom menu 633
15.4 PowerShell script debugging features 638
The Set-PSDebug cmdlet 638 ✦ Nested prompts and the
Suspend operation 643
15.5 The PowerShell v2 debugger 647
The graphical debugger 648
15.6 Command-line debugging 652
Working with breakpoint objects 653 ✦ Setting breakpoints

on commands 656 ✦ Setting breakpoints on variable
assignment 657 ✦ Debugger limitations and issues 658
15.7 Summary 659
Part 2 Using PowerShell 661
16 Working with files, text, and XML 663
16.1 PowerShell and paths 664
Providers and the core cmdlets 664 ✦ Working with
PSDrives 665 ✦ Working with paths that contain
wildcards 667 ✦ Suppressing wildcard processing
in paths 668 ✦ The -LiteralPath parameter 670
The Registry provider 671
16.2 File processing 672
Reading and writing files 674 ✦ Writing files 679 ✦ All
together now—reading and writing 680 ✦ Performance caveats
with Get-Content 680
16.3 Processing unstructured text 681
Using System.String to work with text 681 ✦ Using hashtables to
count unique words 684 ✦ Using regular expressions to
manipulate text 686 ✦ Searching files with the Select-String
cmdlet 688
16.4 XML structured text processing 693
Using XML as objects 693 ✦ Adding elements to an XML
object 695 ✦ Loading and saving XML files 697
Processing XML documents in a pipeline 701 ✦ Processing
XML with XPath 702 ✦ A hint of XLinq 709 ✦ Rendering
objects as XML 711
16.5 Summary 717
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xvi CONTENTS
17 Extending your reach with .NET 719

17.1 Using .NET from PowerShell 720
.NET basics 720 ✦ Working with assemblies 721 ✦ Finding
types 725 ✦ Creating instances of types 727 ✦ Defining new
types with Add-Type 729 ✦ Working with generic types 739
17.2 PowerShell and the internet 740
Retrieving a web page 740 ✦ Processing an RSS feed 742
17.3 PowerShell and graphical user interfaces 743
PowerShell and WinForms 744 ✦ Creating a winforms
module 750
PowerShell and Windows Presentation Foundation 753
17.4 Summary 759
18 Working with COM 760
18.1 Working with COM in PowerShell 761
Creating COM objects 761 ✦ Identifying and locating COM
classes 762
18.2 Automating Windows with COM 764
Exploring with the Shell.Application class 765 ✦ Managing
browser windows using COM 767 ✦ A browser window
management module 770
18.3 Working with the WScript.Shell class 777
18.4 Using COM to manage applications 779
Looking up a word using Internet Explorer 779 ✦ Using
Microsoft Word to do spell checking 781
18.5 The WSH ScriptControl class 783
Embedding VBScript code in a PowerShell script 784
Embedding JScript code in a PowerShell script 785
18.6 Working with the Windows Task Scheduler 786
Getting started with the Schedule.Service class 786 ✦ Listing
running tasks 787 ✦ Creating a new scheduled task 788
Credentials and scheduled tasks 789 ✦ Viewing the life cycle

of a task 792
18.7 Issues with COM 793
64-bit vs. 32-bit issues 793 ✦ Threading model problems 793
Interop assemblies, wrappers, and typelibs 793
18.8 Summary 795
19 Management objects: WMI and WS-MAN 797
19.1 Working with WMI in PowerShell 798
Exploring WMI 798 ✦ The WMI infrastructure 799
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CONTENTS xvii
19.2 The WMI cmdlets 801
The WMI cmdlet common parameters 802 ✦ The Get-WmiObject
cmdlet 804 ✦ The Set-WmiInstance cmdlet 813 ✦ The
Invoke-WmiMethod cmdlet 819 ✦ The Remove-WmiObject
cmdlet 822
19.3 The WMI object adapter 824
The WMI type accelerators 825 ✦ Putting modified WMI objects
back 828
19.4 Exploring WS-Man 830
The WS-Man cmdlets 831 ✦ Using Get-WSManInstance to
retrieve management data 832 ✦ Updating resources using
Set-WSManInstance 840 ✦ Invoking methods with
Invoke-WSManAction 841
19.5 Summary 845
20 Responding in real time with eventing 847
20.1 Foundations of event handling 848
20.2 Synchronous events 849
Synchronous eventing in GUIs 850 ✦ Delegates and
delegation 850
20.3 Asynchronous events 853

Subscriptions, registrations, and actions 854 ✦ The eventing
cmdlets 854
20.4 Working with asynchronous .NET events 855
Writing a timer event handler 856 ✦ Managing event
subscriptions 859
20.5 Asynchronous event handling with scriptblocks 860
Automatic variables in the event handler 860 ✦ Dynamic
modules and event handler state 862
20.6 Queued events and the Wait-Event cmdlet 863
20.7 Working with WMI events 866
WMI event basics 866 ✦ Class-based WMI event
registration 867 ✦ Query-based WMI event
registrations 871
20.8 Engine events 875
Predefined engine events 875 ✦ Generating events in functions
and scripts 876
20.9 Remoting and event forwarding 877
Handling remote EventLog events 879 ✦ Serialization issues with
remote events 880
20.10 How eventing works 882
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20.11 Summary 885
21 Security, security, security 888
21.1 Introduction to security 889
What security is and what it isn’t 889 ✦ Security: perception and
reality 890
21.2 Security modeling 891
Introduction to threat modeling 891 ✦ Classifying threats using
the STRIDE model 892 ✦ Security basics: threats, assets, and

mitigations 893
21.3 Securing the PowerShell environment 897
Secure by default 897 ✦ Enabling scripting with execution
policy 898
21.4 Signing scripts 904
How public key encryption and one-way hashing work 904
Signing authorities and certificates 905 ✦ Self-signed
certificates 905 ✦ Using a certificate to sign a script 909
Enabling strong private key protection 913 ✦ Using the PFX file
to sign a file 915
21.5 Writing secure scripts 916
21.6 Using the SecureString class 916
Creating a SecureString object 917 ✦ The SecureString
cmdlets 918 ✦ Working with credentials 919 ✦ Avoiding
Invoke-Expression 923
21.7 Summary 926
index 929
appendix A Comparing PowerShell to other languages
appendix B Examples
appendix C PowerShell Quick Reference
appendix D Additional PowerShell topics
Appendixes are available for download from
www.manning.com/WindowsPowerShellinActionSecondEdition
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xix
preface
Well, it’s been a wild ride since the first edition of this book was released. At that
time, PowerShell had just shipped and had a fairly limited scope of influence. Things
have changed a lot. PowerShell now ships in the box with Windows (at least Win-
dows 7 and Server 2008 R2). The number of PowerShell users is now in the hundreds

of thousands, if not millions (this is not a formal estimate—I just looked at some of
the download counters for PowerShell-related tools and went from there).
One of the biggest events from my perspective was the release of PowerShell version
2 in July of 2009. Obviously it was time for a sequel to the book. I put together a short
proposal and estimate of the amount of work needed to update the book. The initial
estimate was for a few months of work—a couple of new chapters, a few updates here
and there, and we’re good to go. Wow, was I ever wrong about that! PowerShell v2
was a really big release.
When you are in the middle of something, working heads down, you tend to lose
perspective of the overall project—that old forest/trees problem. It wasn’t until I was
preparing a talk for MMS (Microsoft Management Summit) that I realized just how
BIG it was. In a one-hour talk, we barely had time to list all of the new stuff, much
less describe it in detail. But describing it in detail was exactly what I needed to do and
that’s why this book took a great deal longer to write than anticipated. It’s also much
bigger than I had expected or wanted. At one point it was double the size of the first
edition. So we cut some stuff that was no longer as relevant with PowerShell v2, moved
some stuff into the online appendixes, and capped the book at about 1000 pages.
So why write the book in the first place? The answer is the same now as it was
then—I wanted the PowerShell community to have a way to see “inside the box” and
have a more intimate insight into the goals and motivations behind PowerShell.
Although PowerShell draws heavily from existing technologies, it combines them in
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xx PREFACE
novel ways. This kind of novelty leads to misunderstandings which then turn into
urban myths, like PowerShell does X because its designers were kitten-eating aliens.
(Trust me—we’re not.)
As we showed our work to the world I found that there were a number of questions
that were being asked over and over again. These questions would usually arise as a
result of some prior language experience that the user had. Typically a simple expla-
nation was all it took to clear up the confusion. Unfortunately we couldn’t keep

answering these questions over and over on a one-by-one basis; that just couldn’t scale.
There needed to be a way to gather this information together in one place. The book
was my attempt to address that problem, and the second edition continues on with
this goal.
I continue to be amazed at just how much power comes out of the synergy of the
various technologies underlying PowerShell. We see this in our own internal uses of
PowerShell at Microsoft as well as in what the community has done with it. And so
a second goal of this book was to try and foster that creativity by conveying just how
capable PowerShell is.
And finally, this is the book I wanted to read. I love programming languages and
the best books are the ones that explain not only what but also why. Look at the books
that continue to sell year after year: Kernighan and Ritchie’s The C Programming Lan-
guage, Stroustrup’s book on
C++, and Ousterhout’s book on TCL. The TCL book in
particular describes a very early version of the TCL language, has never been updated,
and yet it continues to sell. Why? Because these books give the reader something more
than just technical detail. They convey a sense of the overall design and some element
of the intent of the designer. (Let me know if I succeeded, okay?)
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xxi
acknowledgments
First and foremost, this book is for my wife Tina. I could not have done it without
her patience, support, and encouragement. She kept me fed and sane, and she even
read early drafts of material about which she knows nothing. Now that’s support! She
also contributed the Gnome picture in chapter 21 and the bird-watching information
and pictures in chapter 2. And I can now recognize the call of the California quail.
Thanks to my parents for their love and support over the years. Yes, I am finally
done with the second edition!
Of course, there wouldn’t be a PowerShell book without a PowerShell product in
the first place and PowerShell wouldn’t exist without the vision of its chief architect

Jeffrey Snover. He was kind enough to do extensive reviews of both editions of the
book. The book, like the product, has benefited greatly from his insight and sugges-
tions.
PowerShell v2 would also not have been possible without the continued efforts on
the part of Kenneth Hansen, lead Program Manager of the PowerShell team. Kenneth
provided most of the day-to-day leadership during the Version 2/Windows 7 release
cycle. He continues to be one of the strongest advocates for the customer that I’ve seen
at Microsoft.
I’d like to thank the following PowerShell team members who took time to review
specific chapters: Jason Shirk, who implemented most (all?) of the advanced function
features in v2, reviewed chapters 7 and 8. Refaat Issa and Lucio Silveira, who were
responsible for the design (Refaat) and implementation (Lucio) of the
ISE, reviewed
chapter 15 which covers the ISE.
To all of the MEAP readers and reviewers, many thanks for your feedback. I’ve
incorporated as much of it as possible (boy, I make a lot of typos). In particular, I’d
like to thank the following: Peter Johnson, Jonathan Medd, Sam Abraham, Andrew
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xxii ACKNOWLEDGMENTS
Tearle, Keith Hill, Richard Siddaway, Paul Grebenc, Kirk Freiheit, Tony Niemann,
Amos Bannister, Jeff Copeland, Marcus Baker, Massimo Perga, Tomas Restrepo,
Jason Zions, Oisin Grehan, Kanwal Khipple, Brandon Shell, Bernd Schandl, and
Matthew Reynolds. Thanks to all of you for your patience. This book took way, way
too long to complete.
Finally, special thanks to all of the people who piled on at the end of the project
to finally get it done: Cynthia Kane, my development editor, who is still talking to me
(I think), even after all of the missed deadlines; also Liz Welch, Mary Piergies, Tiffany
Taylor, and everyone else at Manning who helped get this book out the door. All I
can say is thanks, and thanks again.
And more super-special thanks to three of our wonderful PowerShell MVPs who

helped enormously with the final reviews. Marco Shaw was the technical proofreader
who read the chapters during production. Jeffrey Hicks, a fine author in his own right,
helped with the last set of “author” reviews. And Aleksandar Nikolic´ went above and
beyond the call, turning around reviewed chapters stunningly quickly, and then
reviewing the reviews! Dude, you’re a lifesaver!
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xxiii
about this book
Windows PowerShell is the next-generation scripting environment created by Micro-
soft. It’s designed to provide a unified solution for Windows scripting and automa-
tion, able to access the wide range of technologies such as .NET, COM, and WMI
through a single tool. Since its release in 2006, PowerShell has become the central
component of any Windows management solution. In addition, due to PowerShell’s
comprehensive support for .NET, it also has broad application potential outside of the
system administration space. PowerShell can be used for text processing, general
scripting, build management, creating test frameworks, and so on.
This book was written by one of the principal creators of PowerShell to enable users
to get the most out of the PowerShell environment. Using many examples, both small
and large, this book illustrates the features of the language and environment and shows
how to compose those features into solutions, quickly and effectively.
Note that, because of the broad scope of the PowerShell product, this book has a
commensurately broad focus. It was not designed as a cookbook of pre-constructed
management examples, like how to deal with Active Directory or how to script
Exchange. Instead it provides information about the core of the PowerShell runtime
and how to use it to compose solutions the “PowerShell Way.” After reading this book,
the PowerShell user should be able to take any example written in other languages like
C# or Visual Basic and leverage those examples to build solutions in PowerShell.
Who should read this book?
This book is designed for anyone who wants to learn PowerShell and use it well.
Rather than simply being a book of recipes to read and apply, this book tries to give

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xxiv ABOUT THIS BOOK
the reader a deep knowledge about how PowerShell works and how to apply it. As a
consequence, all users of PowerShell should read this book.
So, if you’re a Windows sysadmin, this book is for you. If you’re a developer and
you need to get things done in a hurry, if you’re interested in .NET, or just if you like
to experiment with computers, PowerShell is for you and this book is for you.
Roadmap
The book is divided into two major parts plus four appendixes (which are available
online from the publisher’s website). The two parts of the book are “Learning Power-
Shell” and “Using PowerShell.”
Part 1, “Learning PowerShell,” is a comprehensive tour of the PowerShell language
and runtime. The goal is to introduce new PowerShell users to the language as well
as to provide experienced users with a deep insight into how and why things are the
way they are.
In part 1, we look at all aspects of the PowerShell language including the syntax,
the type system, and so on. Along the way we present examples showing how each fea-
ture works. Because the goal of the first part of the book is to focus on the individual
features of the environment, most of the examples are quite small and are intended to
be entered in an interactive session. The second part of this book focuses on larger
examples that bring the individual features together to build larger applications.
Chapter 1 begins with some history and the rationale for why PowerShell was cre-
ated in the first place. It then proceeds through a quick tour of the features of the envi-
ronment. The remaining chapters in part 1 cover each element of the language,
starting with basic PowerShell concepts in chapter 2.
Chapter 3 introduces the PowerShell type system and discusses its relationship to
.NET. This chapter also presents the syntax for each of the PowerShell literal data types.
The discussion of operators and expressions (PowerShell has lots of these) begins in
chapter 4 which covers the basic arithmetic, comparison, and assignment operators.
It also covers the wildcard and regular expression pattern matching operators.

Chapter 5 continues the discussion of operators with the advanced operations for
working with arrays (indexing, slicing) and objects (properties and methods). It also
covers output redirection and the formatting operator, and introduces PowerShell
variables.
Chapter 6 covers the PowerShell language constructs like
if
statements and loops.
Chapter 7 introduces programming in PowerShell and covers basic functions, vari-
able scoping, and other programming-related topics.
Chapter 8 builds on the material in chapter 7, covering advanced function meta-
data, scripting, and how to create in-line documentation for scripts and functions.
Chapter 9 covers the basics of how to use PowerShell modules and how to create
your own basic modules.
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