10 POWERSHELL MISTAKES, TRIP-UPS

AND TRAPSJEFFERY HICKS

PROF. POWERSHELL

WHO AM I?• Windows PowerShell MVP• PowerShell Author

• Learn PowerShell 3 in a Month of Lunches (with Don Jones)

• Learn PowerShell Toolmaking in a Month of Lunches (with Don Jones)

• PowerShell in Depth (with Don Jones & Richard Siddaway)

• Managing Active Directory with Windows PowerShell: TFM 2nd Ed.

• IT trainer and consultant• http://jdhitsolutions.com/blog• http://twitter.com/jeffhicks

#1 DON’T USE WRITE-HOST

• Write-Host writes to the console, not the pipeline• You can only work with objects written to the pipeline• Puppies are hurt when you use Write-Host• Unless you use as intended

#2 IT’S ALL ABOUT THE OBJECTS

• Don’t try to parse text• Don’t try to concatenate• Everything in PowerShell is an object• Learn how to use Get-Member

#3 BOOLEANS ARE OBJECTS, TOO

• $True and $False are not strings• The cool PowerShell kids don’t compare

#4 DON’T FALL INTO THE ALIAS TRAP

• Aliases are fine for interactive sessions• You know what you’re typing• Aliases disguise the real command

#5 VARIABLE VULNERABILITY

• This isn’t VBScript• Variable names should be meaningful• Avoid re-using variables for different object types

#6 POWERSHELL IS NOT .NET PROGRAMMING

• Use cmdlets wherever possible• .NET classes and methods are for exceptions• …or large scale performance benefits

#7 POWERSHELL IS NOT VBSCRIPT

• PowerShell requires a new paradigm• Don’t turn VBScript into PowerShell• Objects in the pipeline

#8 DON’T MAKE ERRORS GO AWAY

• Don’t turn off error pipeline• $ErrorActionPreference = "SilentlyContinue"

• Makes troubleshooting more difficult• Use Try/Catch and learn how to handle errors

#9 DON’T RE-INVENT THE WHEEL

• Don’t try to duplicate PowerShell functionality• No need to write your own help routine• Don’t try to re-invent cmdlets using .NET

#10 NOT EVERYTHING IS A ONE-LINER

• One-line commands can be efficient• Great for interactive console• Not necessarily a benefit in scripting• Don’t code yourself into a corner

QUESTIONS AND ANSWERS

RECOMMENDATIONS

• Write objects to the pipeline• Use cmdlets where possible• No aliases or shortcuts in scripts• Learn how to handle errors• Read the help and examples

RESOURCES• Learn PowerShell 3 in a Month of Lunches by Don Jones and Jeffery

Hicks • Learn PowerShell Toolmaking in a Month of Lunches by Don Jones

and Jeffery Hicks• The Lonely Administrator (http://jdhitsolutions.com/blog)• Prof. PowerShell (http://mcpmag.com/articles/list/prof-

powershell.aspx• PowerShell.org

THANK YOU

http://jdhitsolutions.com/blog

jhicks@jdhitsolutions.com

@JeffHicks

http://gplus.to/jeffhicks