Book Image

Mastering Windows PowerShell Scripting (Second Edition) - Second Edition

By : Brenton J.W. Blawat
Book Image

Mastering Windows PowerShell Scripting (Second Edition) - Second Edition

By: Brenton J.W. Blawat

Overview of this book

PowerShell scripts offer a handy way to automate various chores. Working with these scripts effectively can be a difficult task. This comprehensive guide starts from scratch and covers advanced-level topics to make you a PowerShell expert. The first module, PowerShell Fundamentals, begins with new features, installing PowerShell on Linux, working with parameters and objects, and also how you can work with .NET classes from within PowerShell. In the next module, you’ll see how to efficiently manage large amounts of data and interact with other services using PowerShell. You’ll be able to make the most of PowerShell’s powerful automation feature, where you will have different methods to parse and manipulate data, regular expressions, and WMI. After automation, you will enter the Extending PowerShell module, which covers topics such as asynchronous processing and, creating modules. The final step is to secure your PowerShell, so you will land in the last module, Securing and Debugging PowerShell, which covers PowerShell execution policies, error handling techniques, and testing. By the end of the book, you will be an expert in using the PowerShell language.
Table of Contents (24 chapters)
Title Page
Credits
About the Authors
About the Reviewer
www.PacktPub.com
Customer Feedback
Preface

Variable scope


Variables may be declared in a number of different scopes. The scopes are:

  • Local
  • Global
  • Private
  • Script
  • A numeric scope relative to the current scope

Note

More about scopes:The help document, About_Scopes (Get-Help about_Scopes), has more examples and detail.

By default, variables are placed in Local scope. Access to variables is hierarchical: a child (scopes created beneath a parent) can access variables created by the parent (or ancestors).

Local and Global scope

When creating a variable in the console (outside of functions or script blocks), the Local scope is Global. The Global scope can be accessed from inside a function (child) because it is a parent scope:

Remove-Variable thisValue -ErrorAction SilentlyContinue 
$Local:thisValue = "Some value" 
"From Local: $local:thisValue"          # Accessible 
"From Global: $global:thisValue"        # Accessible 
 
function Test-ThisScope { 
    "From Local: $local:thisValue"      # Does not exist 
    "From Global: $global:thisValue"    #...