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

Grouping


A group in a regular expression serves a number of different possible purposes:

  • To denote repetition (of more than a single character)
  • To restrict alternation to a part of the regular expression
  • To capture a value

Repeating groups

Groups may be repeated using any of the quantifiers. The regular expression that tentatively identifies an IP address can be improved using a repeated group. The starting point for this expression is as follows:

[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+

In this expression, the [0-9]+ term followed by a literal . is repeated three times. Therefore, the expression can become as follows:

([0-9]+\.){3}[0-9]+

The expression itself is not very specific (it will match much more than an IP address), but it is now more concise. This example will be taken further later in this chapter.

If * is used as the quantifier for the group, it becomes optional. If faced with a set of version numbers ranging in formats from 1 to 1.2.3.4, a similar regular expression might be used:

[0-9]+(\.[0-9...