Adam Bertram

Building Better PowerShell Code

Applying Proven Practices One Tip at a Time

1st ed.
Adam Bertram
Evansville, IN, USA
ISBN 978-1-4842-6387-7e-ISBN 978-1-4842-6388-4
https://doi.org/10.1007/978-1-4842-6388-4
© Adam Bertram 2020
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This book is dedicated to all of the tech professionals out there that have been intrigued by PowerShell and have taken the time to dig in, learn, and better themselves with knowledge.

Introduction

This book was created out of necessity. There are many books out there on how to learn PowerShell. You’ll also find thousands of articles and blog posts on PowerShell best practices. But there wasn’t an entire collection of PowerShell learning and best practices brought together before.

Each chapter in this book is broken down by chapter with multiple “tips” inside. Each chapter is a bucket for the kinds of tips you can expect to read about. Each tip is a best practice. Tips are short, actionable steps you can take today to help you improve your PowerShell scripts.

Tips do not go into major detail. There are other resources out there for that. The tips in this book are not meant to be exhaustive how-tos but to rather act as a checklist for actions to take. With each tip, you will typically find an example to solidify your understanding of the tip.

All tips within this book should be treated as universal across all PowerShell versions and platforms from Windows PowerShell 5.1 and later including all PowerShell Core versions. If you see an example using code, assume that it will work in your PowerShell version of choice. All examples were written to be as generic as possible.

All tips in this book were written by me, but many were contributed by the PowerShell community. If a tip did come from the community, the community member will be referenced.

Who Is This Book For?

This book is for anyone wanting to learn how to write better PowerShell code. The book’s examples are primarily targeted to the IT professional, although anyone writing PowerShell for any purpose can get a lot from this book.

This book is not meant to be “training,” per se. It’s not specifically targeted at any level of PowerShell expertise. You will find tips in this book ranging from the basic level all the way up to the advanced level. It’s up to you to skip those tips that don’t apply to you and soak up the ones that do.

Read over this book periodically throughout your career. You’ll find that each tip will vary based on specific contexts, use cases, and expertise levels. Once you find yourself at that level, you’ll be able to understand and get more out of those tips.

Book Resources

You will find all code referenced in this book in the (a) GitHub repository called PowerShellTipsTo​WriteBy.

Acknowledgments

This book, along with all of my other career projects, could not have been possible without my wife, Miranda. She’s the rock of our household and has allowed me to pursue projects regardless of how crazy they have been and has supported me for nearly 20 years now.

I also want to acknowledge all of those that have reached out and let me know how much my work means to you. It may mean a lot to you, but trust me, it means more to me to hear stories of how I’ve helped throughout your career.

Table of Contents
Chapter 1:​ Do the Basics 1
Plan Before You Code 1
Don’t Reinvent the Wheel 2
Build Functions As Building Blocks 2
Build Reusable Tools 3
Don’t Focus Purely on Performance 3
Build Pester Tests 4
Implement Error Handling 4
Build Manageable Code 5
Don’t Skimp on Security 5
Log Script Activity 6
Parameterize Everything 6
Limit Script and Function Input 7
Maintain Coding Standards 7
Code in Context 8
Return Informational Output 8
Understand Your Code 9
Use Version Control 9
Write for Cross-Platform 10
Write for the Next Person 10
Use Visual Studio Code 11
Chapter 2:​ Don’t Reinvent the Wheel 13
Use Community Modules 13
Leverage Others’ Work 14
Chapter 3:​ Use Visual Studio Code 17
Install the PowerShell Extension 19
Integrate VS Code with Git 19
Chapter 4:​ Plan Before You Code 21
Write Comments Before Coding 21
Use Your Code As a Todo List 23
Chapter 5:​ Create Building Blocks with Functions 25
Write Functions with One, Single Goal 25
Build Functions with Pipeline Support 27
Save Commonly Used, Interactive Functions to Your User Profile 30
Chapter 6:​ Parameterize Everything 33
Don’t Hardcode.​ Always Use Parameters 33
Use Parameter Sets When All Parameters Should Not Be Used at Once 36
Use a PSCredential Object Rather Than a Separate Username and Password 40
Chapter 7:​ Log Script Activity 43
Use a Logging Function 43
Clean Up Verbose Messages 46
Chapter 8:​ Build with Manageability in Mind 49
DRY:​ Don’t Repeat Yourself 49
Don’t Store Configuration Items in Code 51
Always Remove Dead Code 53
Chapter 9:​ Be Specific 55
Explicitly Type All Parameters 55
Always Use Parameter Validation When Possible 57
Always Define a Function’s OutputType 59
Write Specific Regular Expressions 61
Chapter 10:​ Write for the Next Person 63
Give Your Variables Meaningful Names 63
String Substitution 65
Keep Aliases to the Console Only, Not in Scripts 66
Put Functions in Alphabetical Order in a Module 67
Explain Regular Expressions with Comments 68
Write Comment-Based Help 69
Weigh the Difference Between Performance and Readability 71
Chapter 11:​ Handle Errors Gracefully 73
Force Hard-Terminating Errors 73
Avoid Using $?​ 76
Chapter 12:​ Don’t Skimp on Security 79
Sign Scripts 79
Use Scriptblock Logging 81
Never Store Sensitive Information in Clear Text in Code 82
Don’t Use Invoke-Expression 84
Use PowerShell Constrained Language Mode 86
Chapter 13:​ Stick to PowerShell 87
Use Native PowerShell Where Possible 87
Use Approved, Standard Function Names 89
Chapter 14:​ Build Tools 91
Think Ahead and Build Abstraction “Layers” 91
Wrap Command-Line Utilities in Functions 97
Make Module Functions Return Common Object Types 98
Ensure Module Functions Cover All the Verbs 100
Chapter 15:​ Return Standardized, Informational Output 101
Use Progress Bars Wisely 101
Leave the Format Cmdlets to the Console 103
Use Write-Verbose 105
Use Write-Information 107
Ensure a Command Returns One Type of Object 108
Only Return Necessary Information to the Pipeline 110
Chapter 16:​ Build Scripts for Speed 113
Don’t Use Write-Host in Bulk 113
Don’t Use the Pipeline 114
Use the foreach Statement in PowerShell Core 115
Use Parallel Processing 117
Use the .​NET StreamReader Class When Reading Large Text Files 119
Chapter 17:​ Use Version Control 121
Create Repositories Based on a Purpose 121
Commit Code Changes Based on Small Goals 122
Create a Branch Based on a Feature 122
Use a Distributed Version Control Service 123
Chapter 18:​ Build and Run Tests 125
Learn the Pester Basics 125
Leverage Infrastructure Tests 126
Automate Pester Tests 127
Use PSScriptAnalyzer​ 128
Chapter 19:​ Miscellaneous Tips 131
Write for Cross-Platform 131
Don’t Query the Win32_​Product CIM Class 133
Create a Shortcut to Run PowerShell As Administrator 134
Store “Formattable” Strings for Later Use 136
Use Out-GridView for GUI-Based Sorting and Filtering 137
Don’t Make Automation Scripts Interactive 139
Chapter 20:​ Summary 141
Index 143
About the Author
Adam Bertram
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is a 22-year veteran of IT and experienced online business professional. He’s an entrepreneur, Microsoft MVP, blogger at adamtheautomator.com, trainer, and writer for multiple technology companies. Catch up on Adam’s articles at adamtheautomator.com, connect on linkedin.com/in/AdamBertram/, or follow him on twitter.com/adbertram.

 
About the Technical Reviewer
Vikas Sukhija
../images/501963_1_En_BookFrontmatter_Figc_HTML.jpg
has over 16 years of IT infrastructure experience. He is certified/worked on various Microsoft and related technologies.

He has been awarded five times with Microsoft Most Valuable Professional title (thrice in Cloud and Datacenter management (PowerShell) and twice in the Office 365 category).

With his experience on messaging and collaboration technologies, he has assisted clients in migrating from one messaging platform to another.

He has utilized PowerShell for automation of various monotonous tasks as well as created self-service solutions for users.

He has been recognized many times by clients for automations that resulted in direct/indirect cost avoidance.

He is playing key roles with various large clients in the implementation and adoption of Office 365.

He is the owner and author of the http://TechWizard.cloud ,http://SysCloudPro.comblog site.

He is also the owner and author of the https://www.facebook.com/TechWizard.cloud Facebook page.

 
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