from vb script to powershell

Convert Your Brain from VBScript to Convert Your Brain from VBScript to PowerShellPowerShellDon JonesDon JonesSenior Partner & Principal TechnologistConcentrated Technology, LLC

This slide deck was used in one of our many conference presentations. We hope you enjoy it, and invite you to use it

within your own organization however you like.

For more information on our company, including information on private classes and upcoming conference appearances, please

visit our Web site, www.ConcentratedTech.com.

For links to newly-posted decks, follow us on Twitter:@concentrateddon or @concentratdgreg

This work is copyright ©Concentrated Technology, LLC

http://www.ConcentratedTech.com/

CAUTION: DEMOS AHEADCAUTION: DEMOS AHEAD

This is a demonstration-intensive session (very few slides)

I will capture a shell transcript and save all of my scripts

You can download these (in a week or so) from ConcentratedTech.com (there’s a “Conference Materials” link in the menu)

3 • Don Jones • ConcentratedTech.com

Change Your BrainChange Your Brain

VBScript is a scripting language PowerShell is a shell that has some

scripting capabilities In many cases you can do a line-by-

line conversion from VBScript to PowerShell – but you’re not taking advantage of PowerShell’s strengths

We’re going to look at some specific scenarios and try to change your brain!


The LanguageThe Language

PowerShell’s “scripting language” is about 14 keywords

It provides most of the language constructs you know from VBScript

Let’s look at where to find the help on them, because we aren’t really going to focus on them a lot here

We will look at Switch because it’s so different from Select Case


Changing Your BrainChanging Your Brain

GOOD If & Switch – good for

adding conditional commands in complex processes

AVOID ForEach – if you’re

enumerating a collection, you’re likely doing it wrong

Loops of any kind – often not needed, and a sign of a “VBS” approach rather than a “PSH” approach


Example #1Example #1

Reading a list of computer names and connecting to them via WMI

We’ll look at a VBS-style approach, and then a more compact PowerShell-style approach

Example #2Example #2

Combining info from multiple sources into a single table

Again, VBS approach first – then a couple of PowerShell-style approaches


The Trick with PowerShellThe Trick with PowerShell

PowerShell commands intrinsically provide collection enumeration within the pipeline

Many PowerShell command parameters natively accept collections/arrays (how can you tell?) so you don’t have to enumerate over the collection/array yourself

(Parens) let you embed embed entire commands as input to another command’s parameters

Many commands can accept other commands as parameters


Stop Producing TextStop Producing Text

Never use Write-Host. Write-Output to the pipeline – and

write objects, not text Also:

– Write-Debug ($DebugPreference)– Write-Error– Write-Warning– Write-Verbose

Produce objects


Modularization, the PowerShell Modularization, the PowerShell WayWay

Every unit – script, function, whatever – should do one thing and either:– Produce NO output– Produce ONE consistent kind of output to

the pipeline

Utilize verb-noun naming convention Use consistent parameter names Create functions designed to work

within the pipeline (ideally, “script cmdlets” or Advanced Functions)

Add help using comments


Never Do ThisNever Do This

Produce a list… …output it to a text file… …and then read that back in and

parse it.

Text is only to be used as a final output – not an intermediary

Never try to parse the output of a table (e.g., Format-Table) – here’s why


Where are my functions?!?Where are my functions?!?

PowerShell doesn’t have intrinsic data-manipulation functions

Instead, look at methods of…– String objects– DateTime objects

Also look at the static methods of the [Math] class, e.g., [Math]::Abs(-5)


Any Questions? Any Questions? & Closing Thoughts& Closing Thoughts

Use the pipeline. The pipeline isn’t a feature of

PowerShell, it’s at the heart and soul of how the shell is structured

For a lot of tasks, a command sequence (“pipeline”) can be a lot shorter than a VBScript – and just as effective

Think reusability – output objects, since those have maximum re-use.


Final Notes…Final Notes…

Please be sure to submit a session evaluation form!

Download slides & materials from www.ConcentratedTech.com within one week!

Blog, URLs, and other information is also available at www.ConcentratedTech.com for your reference

More resources at www.ShellHub.com Thank you very much!




http://www.ShellHub.com/

This slide deck was used in one of our many conference presentations. We hope you enjoy it, and invite you to use it

within your own organization however you like.

For more information on our company, including information on private classes and upcoming conference appearances, please

visit our Web site, www.ConcentratedTech.com.

For links to newly-posted decks, follow us on Twitter:@concentrateddon or @concentratdgreg

This work is copyright ©Concentrated Technology, LLC


from vb script to powershell

Technology

parameters don jones

comments don jones

menu don jones

case don jones

psh approach don jones

style approaches don

couple of powershell

powershell way