Brushing up on PowerShell

Over the last couple of days, I have been working with PowerShell on a project. My usage of PowerShell in the past has been mostly for one off tasks or for a tasks that I need to get done really quickly so I can move on to the next. My current project caused me to think about PowerShell as a tool for creating re-usable scripts.

To load additional modules and snap-ins use the commands:

 Import-Module  

and

 Add-PSSnapIn  

.
If you try to load the same snap-in more in the same session an error occurs. One way around is to ignore the error.

 Add-PSSnapin -Name "Microsoft.SharePoint.PowerShell" -ErrorAction SilentlyContinue  

Great care must be taken when using variables. A simple typo can lead to a lot of confusion. It is also worthwhile to read up on variable scope.

 help about_scope  

PowerShell allows you to create methods or functions within a script. The basic syntax is

 function  { script block }  

A quick example of creating a function to add two numbers together and calling the function.

 function Add ([int] $x, [int] $y) {   
   $results = $x + $y;  
   Write-Host "Results $results";  
 }  
 Add 3 4  

In the above example, I am doing a few small things that are more personal preference than anything else. There are multiple ways to create parameters. I like to create parameters on the same line as the function name. I also like to add the datatypes. This just gives a me a bit of clue as to what the function would like to have for data. I am also using semi-colons at the end of each line. This comes from my history of working with C, C++, Java, JavaScript, and C#.

You will notice in calling the function, "Add 3 4", parameter are separated by spaces.

Single line comments start with the # sign.

 #A simple one line comment  

Block comments are encased in <# #>

 <#  
 This is a multiple line comment  
 or block comment  
 #>  

Accessing the help system within PowerShell is straight-forward. There are multiple key words that can be used.

 Get-Help  

,

 Help  

, or

 Man  

Calling the help system on the cmdlet Get-Content.

 man Get-Content  

The help system also comes with a set of switches for showing the full listing.

 man Get-Content -full