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  • Book Overview & Buying PowerShell Troubleshooting Guide
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PowerShell Troubleshooting Guide

PowerShell Troubleshooting Guide

By : Michael Shepard
4.7 (3)
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PowerShell Troubleshooting Guide

PowerShell Troubleshooting Guide

4.7 (3)
By: Michael Shepard
Buy this Book

Overview of this book

The techniques in this book apply to beginners who have just started to learn PowerShell, as well as advanced scripters who have a good grasp of the language.
Table of Contents (10 chapters)
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Preface
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Preface
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What this book covers
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What you need for this book
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Who this book is for
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Conventions
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Reader feedback
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Customer support
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1
1. PowerShell Primer
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1. PowerShell Primer
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Introduction
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Cmdlets
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Functions
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Scripts
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Pipelines
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Variables
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Modules
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Further reading
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Summary
2
2. PowerShell Peculiarities
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2. PowerShell Peculiarities
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PowerShell strings
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Function output
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Pipeline processing
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PowerShell error handling
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Further reading
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Summary
3
3. PowerShell Practices
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3. PowerShell Practices
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Filter left
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Format right
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Comment-based help
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Using Write-* cmdlets
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Further reading
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Summary
4
4. PowerShell Professionalism
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4. PowerShell Professionalism
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Naming conventions
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Modularization
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Version control
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Unit testing
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Further reading
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Summary
5
5. Proactive PowerShell
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5. Proactive PowerShell
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Error handling
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CmdletBinding()
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SupportsShouldProcess
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Parameter value validation
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Pipeline input
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Pipelines and function execution
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Parameter type transformation
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#REQUIRES statements
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Set-StrictMode and Set-PSDebug -strict
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Further reading
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Summary
6
6. Preparing the Scripting Environment
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6. Preparing the Scripting Environment
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Validating operating system properties
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Validating service status
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Validating disk and memory availability
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Validating network connectivity
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Further reading
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Summary
7
7. Reactive Practices – Traditional Debugging
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7. Reactive Practices – Traditional Debugging
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Reading error messages
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Using Set-PSDebug
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Debugging in the console
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Debugging in the ISE
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Event logs
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The PSDiagnostics module
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Using –confirm and –whatif
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Reducing input set
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Using Tee-Object to see intermediate results
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Replacing the foreach loop with the foreach-object cmdlet
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Further reading
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Summary
8
8. PowerShell Code Smells
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8. PowerShell Code Smells
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Code smells
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Language-agnostic code smells
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PowerShell-specific code smells
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Missing Param() statements
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Homegrown common parameters
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Unapproved verbs
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Accumulating output objects
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Sequences of assignment statements
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Using untyped or [object] parameters
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Static analysis tools – ScriptCop and Script Analyzer
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Further reading
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Summary
9
Index
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Index

Sequences of assignment statements

As I have mentioned several times, scripting in PowerShell is somewhat different than programming in other languages. A programmer who isn't comfortable with the pipeline might easily fall into the trap of writing code in a style that matches the imperative programming language that he is most familiar with. For instance, filtering and sorting a list of files in a directory could easily be seen as a sequence of operations, as follows:

  1. Get the list of files.

  2. Filter the list of files to match the given criteria.

  3. Sort the remaining list of files.

This thought process could lead to a PowerShell script that looks like this:

function get-sortedFilteredList{
Param($folder,$extension)

    $files = dir $folder
    $matchingFiles = where-object -InputObject $files -FilterScript {$_.Extension -eq $extension}
    $sortedMatches = sort-object -InputObject $matchingFiles -Property Name

    return $sortedMatches
}

While this is a correct solution to the problem in some senses...

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PowerShell Troubleshooting Guide
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