Book Image

Mastering Windows PowerShell Scripting - Third Edition

By : Chris Dent
Book Image

Mastering Windows PowerShell Scripting - Third Edition

By: Chris Dent

Overview of this book

PowerShell scripts offer a handy way to automate various chores, however working effectively with these scripts can be a difficult task. This comprehensive guide starts with the fundamentals before moving on to advanced-level topics to help you become a PowerShell Core 6.0 expert. The first module, PowerShell Core 6.0 Fundamentals, begins with the new features of PowerShell Core 6.0, installing it on Linux, and working with parameters, objects and .NET classes from within PowerShell Core 6.0. As you make your way through the chapters, you'll see how to efficiently manage large amounts of data and interact with other services using PowerShell Core 6.0. You'll be able to make the most of PowerShell Core 6.0's powerful automation feature, where you will have different methods available to parse data and manipulate regular expressions and Windows Management Instrumentation (WMI). After having explored automation, you will enter the extending PowerShell Core 6.0 module, covering asynchronous processing and desired state configuration. In the last module, you will learn to extend PowerShell Core 6.0 using advanced scripts and filters, and also debug issues along with working on error handling techniques. By the end of this book, you will be an expert in scripting with PowerShell Core 6.0.
Table of Contents (27 chapters)
Free Chapter
1
Section 1: Exploring PowerShell Fundamentals
6
Section 2: Working with Data
16
Section 3: Automating with PowerShell
19
Section 4: Extending PowerShell

Alternation

The alternation (or) character in a regular expression is a pipe (|). This is used to combine several possible regular expressions. A simple example is to match a list of words:

'one', 'two', 'three' | Where-Object { $_ -match 'one|three' } 

The alternation character has the lowest precedence; in the previous expression, every value is first tested against the expression to the left of the pipe and then against the expression to the right of the pipe.

The goal of the following expression is to extract strings that only contain the words one or three. Adding the start and the end of string anchors ensures that there is a boundary. However, because the left and right are treated as separate expressions, the result might not be as expected when using the following expression:

PS> 'one', 'one hundred', &apos...