Powershell begin Process End output

Question

hi,
I have the following simple script, this is not running in a function, its running direct in the script

  [CmdletBinding()]
   Param(
     [Parameter(ValueFromPipeline=$True)]
     [String[]]$Computers
   )

   Begin {
      Write-host "Starting Point" -ForegroundColor Yellow

   }

   Process {
   Write-Host $Computers.GetType() -ForegroundColor Red
      Write-Host $Computers

   }

   End {
      Write-host "Remove Variable" -ForegroundColor Yellow

   }

But I don't understand the behavior of the output if the script executed like the following

**.\TestPipline.ps1 -Computers "1","2"**

The output is Starting Point
System.String[]
1 2
Remove Variable

If the script executed like the following "1","2" |.\TestPipline.ps1

The result is displayed correctly, which is like this

Starting Point
System.String[]
1
System.String[]
2
Remove Variable

Notice that in the first execution, the 1 and 2 are passed as a single line(object), but on the second execution, the 1 first passed and processed and then 2.
what I am missing here, how to make 1 and 2 always passed and processed separately

Answer

Hi @Faris Malaeb ,

both of those sources explain why the behavior is different in both cases:

Advanced PowerShell Functions: Begin to Process to End

and also here

Understanding PowerShell Begin, Process, and End blocks

----------

(If the reply was helpful please don't forget to upvote or accept as answer, thank you)
Regards,
Stoyan

Answer

When you pipe an array into a script/function, each element of the array is sent into the pipe individually. When you use that array as a parameter, the entire array is used as a single object. You can get the behavior you want like this:

[CmdletBinding()]
    Param(
      [Parameter(ValueFromPipeline=$True)]
      [String[]]$Computers
    )

    Begin {
       Write-host "Starting Point" -ForegroundColor Yellow

    }

    Process {
        $Computers |
            ForEach-Object{
                Write-Host $_.GetType() -ForegroundColor Red
                Write-Host $_
            }
    }

    End {
       Write-host "Remove Variable" -ForegroundColor Yellow

    }

Share via

Powershell begin Process End output

2 answers

Your answer