book

Learn PowerShell in a Month of Lunches, Fourth Edition

by Tyler Leonhardt, Travis Plunk, James Petty

May 2022

Beginner

360 pages

10h 10m

English

Manning Publications

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forewordprefaceacknowledgmentsabout this bookWho should read this bookAbout the codeliveBook discussion forumabout the authors
1.1 Why you can no longer afford to ignore PowerShell1.1.1 Life without PowerShell1.1.2 Life with PowerShell1.2 Windows, Linux, and macOS, oh my1.3 Is this book for you?1.4 How to use this book1.4.1 The chapters1.4.2 Hands-on labs1.4.3 Supplementary materials1.4.4 Further exploration1.4.5 Above and beyond1.5 Setting up your lab environment1.6 Installing PowerShell1.7 Contacting us1.8 Being immediately effective with PowerShell
2.1 PowerShell on Windows2.2 PowerShell on macOS2.2.1 Installation on macOS2.3 PowerShell on Linux (Ubuntu 18.04)2.3.1 Installation on Ubuntu 18.042.4 Visual Studio Code and the PowerShell extension2.4.1 Installing Visual Studio Code and the PowerShell extension2.4.2 Getting familiar with Visual Studio Code2.4.3 Customizing Visual Studio Code and the PowerShell extension2.5 It’s typing class all over again2.6 What version is this?2.7 Lab
3.1 The help system: How you discover commands3.2 Updatable help3.3 Asking for help3.4 Using help to find commands3.5 Interpreting the help3.5.1 Parameter sets and common parameters3.5.2 Optional and mandatory parameters3.5.3 Positional parameters3.5.4 Parameter values3.5.5 Finding command examples3.6 Accessing “about” topics3.7 Accessing online help3.8 Lab3.9 Lab answers
4.1 Let’s talk security4.1.1 Execution policy4.2 Not scripting, but running commands4.3 The anatomy of a command4.4 The cmdlet naming convention4.5 Aliases: Nicknames for commands4.6 Taking shortcuts4.6.1 Truncating parameter names4.6.2 Using parameter name aliases4.6.3 Using positional parameters4.7 Support for external commands4.8 Dealing with errors4.9 Common points of confusion4.9.1 Typing cmdlet names4.9.2 Typing parameters4.10 Lab4.11 Lab answers
5.1 What are providers?5.2 Understanding how the filesystem is organized5.3 Navigating the filesystem5.4 Using wildcards and literal paths5.5 Working with other providers5.5.1 Windows Registry5.6 Lab5.7 Lab answers

6.1 Connecting one command to another: Less work for you6.2 Exporting to a file6.2.1 Exporting to CSV6.2.2 Exporting to JSON6.2.3 Exporting to XML6.2.4 Out-File6.2.5 Comparing files6.3 Piping to a file6.4 Converting to HTML6.5 Using cmdlets that modify the system: Killing processes6.6 Common points of confusion6.7 Lab6.8 Lab answers
7.1 How one shell can do everything7.2 Extensions: Finding and installing modules7.3 Extensions: Finding and adding modules7.4 Command conflicts and removing extensions7.5 Playing with a new module7.6 Common points of confusion7.7 Lab7.7 Lab answers
8.1 What are objects?8.2 Understanding why PowerShell uses objects8.3 Discovering objects: Get-Member8.4 Using object attributes, or properties8.5 Using object actions, or methods8.6 Sorting objects8.7 Selecting the properties you want8.8 Objects until the end8.9 Common points of confusion8.10 Lab8.11 Lab answers
9.1 Defining the task9.2 Finding the commands9.3 Learning to use the commands9.4 Tips for teaching yourself9.5 Lab9.6 Lab answer
10.1 The pipeline: Enabling power with less typing10.2 How PowerShell passes data down the pipeline10.3 Plan A: Pipeline input ByValue10.4 Plan B: Pipeline input ByPropertyName10.5 When things don’t line up: Custom properties10.6 Working with Azure PowerShell10.7 Parenthetical commands10.8 Extracting the value from a single property10.9 Lab10.10 Lab answers10.11 Further exploration
11.1 Formatting: Making what you see prettier11.2 Working with the default formatting11.3 Formatting tables11.4 Formatting lists11.5 Formatting wide lists11.6 Creating custom columns and list entries11.7 Going out: To a file or to the host11.8 Another out: GridViews11.9 Common points of confusion11.9.1 Always format right11.9.2 One type of object at a time, please11.10 Lab11.11 Lab answers11.12 Further exploration
12.1 Making the shell give you just what you need12.2 Filtering left12.3 Using comparison operators12.4 Filtering objects out of the pipeline12.5 Using the iterative command-line model12.6 Common points of confusion12.6.1 Filter left, please12.6.2 When $_ is allowed12.7 Lab12.8 Lab answers12.9 Further exploration
13.1 The idea behind remote PowerShell13.1.1 Remoting on Windows devices13.1.2 Remoting on macOS and Linux devices13.1.3 Cross-platform remoting13.2 Setting up PSRP over SSH13.2.1 macOS and Linux13.2.2 Setting up SSH on Windows13.3 PSRP over SSH overview13.4 WinRM overview13.5 Using Enter-PSSession and Exit-PSSession for one-to-one remoting13.6 Using Invoke-ScriptBlock for one-to-many remoting13.7 Differences between remote and local commands13.7.1 Deserialized objects13.7.2 Local vs. remote processing13.8 But wait, there’s more13.9 Common points of confusion13.10 Lab13.11 Lab answers13.12 Further exploration
14.1 Making PowerShell do multiple things at the same time14.2 Synchronous vs. asynchronous14.3 Creating a process job14.4 Creating a thread job14.5 Remoting, as a job14.6 Jobs in the wild14.7 Getting job results14.8 Working with child jobs14.9 Commands for managing jobs14.10 Common points of confusion14.11 Lab14.12 Lab answers
15.1 The preferred way: “Batch” cmdlets15.2 The CIM way: Invoking methods15.3 The backup plan: Enumerating objects15.3.1 Making the cmdlets work for you15.4 Let’s speed things up15.5 Common points of confusion15.5.1 Which way is the right way?15.5.2 Diminishing returns of Parallel ForEach15.5.3 Method documentation15.5.4 ForEach-Object confusion15.6 Lab15.7 Lab answers
16.1 Introduction to variables16.2 Storing values in variables16.3 Using variables: Fun tricks with quotes16.4 Storing many objects in a variable16.4.1 Working with single objects in a variable16.4.2 Working with multiple objects in a variable16.4.3 Other ways to work with multiple objects16.4.4 Unrolling properties and methods in PowerShell16.5 More tricks with double quotes16.6 Declaring a variable’s type16.7 Commands for working with variables16.8 Variable best practices16.9 Common points of confusion16.10 Lab16.11 Lab answers16.12 Further exploration
17.1 Prompting for, and displaying, information17.2 Read-Host17.3 Write-Host17.4 Write-Output17.5 Other ways to write17.6 Lab17.7 Lab answers17.8 Further exploration
18.1 Creating and using reusable sessions18.2 Enter-PSSession with session objects18.3 Invoke-Command with session objects18.4 Implicit remoting: Importing a session18.5 Using disconnected sessions18.6 Lab18.7 Lab answers18.8 Further exploration
19.1 Not programming, more like batch files19.2 Making commands repeatable19.3 Parameterizing commands19.4 Creating a parameterized script19.5 Documenting your script19.6 One script, one pipeline19.7 A quick look at scope19.8 Lab19.9 Lab answer
20.1 Starting point20.2 Getting PowerShell to do the hard work20.3 Making parameters mandatory20.4 Adding parameter aliases20.5 Validating parameter input20.6 Adding the warm and fuzzies with verbose output20.7 Lab20.8 Lab answer
21.1 The purpose of regular expressions21.2 A regex syntax primer21.3 Using regex with -Match21.4 Using regex with Select-String21.5 Lab21.6 Lab answers21.7 Further exploration
22.1 The script22.1.1 Parameter block22.1.2 Process block22.2 It’s a line-by-line examination22.3 Lab22.4 Lab answer
23.1 Foreach and Foreach-Object23.1.1 Foreach23.1.2 Foreach-Object23.1.3 Foreach-Object -Parallel23.3 While23.3 Do While23.4 Lab23.5 Lab answers
24.1 Understanding errors and exceptions24.2 Bad handling24.3 Two reasons for exception handling24.4 Handling exceptions24.5 Handling exceptions for noncommands24.6 Going further with exception handling24.7 Lab24.8 Lab answer
25.1 Output everything25.2 One line at a time25.3 Hey, script, stop right there . . . with breakpoints25.4 Lab
26.1 Profiles, prompts, and colors: Customizing the shell26.1.1 PowerShell profiles26.1.2 Customizing the prompt26.1.3 Tweaking colors26.2 Operators: -as, -is, -replace, -join, -split, -contains, -in26.2.1 -as and -is26.2.2 -replace26.2.3 -join and -split26.2.4 -contains and -in26.3 String manipulation26.4 Date manipulation26.5 Dealing with WMI dates26.6 Setting default parameter values26.7 Playing with script blocks26.8 More tips, tricks, and techniques
27.1 Ideas for further exploration27.2 “Now that I’ve read the book, where do I start?”27.3 Other resources you’ll grow to love
A.1 PunctuationA.2 Help fileA.3 OperatorsA.4 Custom property and column syntaxA.5 Pipeline parameter inputA.6 When to use $_

Content preview from Learn PowerShell in a Month of Lunches, Fourth Edition

24 Handling errors

In this chapter, we’ll focus on how to capture, deal with, log, and otherwise handle errors the tool may encounter.

Note PowerShell.org offers a free e-book called The Big Book of PowerShell Error Handling, which dives into this topic from a more technical reference perspective, at https://devopscollective.org/ebooks/. We recommend checking it out once you’ve completed this tutorial-focused chapter.

Before we get started, there are two variables that we need to get comfortable with. The first is the $Error automation variable. This contains an array of error objects that have occurred in your current session, with the most recent error object showing up at $Error[0]. By default, all errors will be put into this variable. You ...