PowerShell function $input parameters

Question

First, I'm just learning PowerShell, but I have programmed in many scripting languages.

I'm writing a script to retrieve output from a command on a remote server and then check that output for the word "running". Right now it retrieves the output of the command, and I have it in my variable, $data. The problem is I'm putting it through my "clean_data" function, and it's not the same contents in the variables that I'm passing to the function.

What I'm wondering is how on Earth does the output of the $data variable have one content when printed to screen, but when passed to a function and immediately printed have a new content? What am I missing?

I just want to loop through the lines that were returned to see how many have "running" in them and print a nice error if there isn't.

CODE (Partial: function and relevant code)

function clean_data($input) {
  Write-Output "Received data"$input
  Write-Output "Cleaning data"
  $output=@()
  foreach ($line in $input) {
     Write-Output "Looking at: "$line.ToString()
     if ($line.ToString().Contains("running")) {
         $output+=$line
     }
   }
   Write-Output $output
   return ,$output
}

$data = Get-Job -id $jobid.id | Receive-Job
Write-output "Data Type: "$data.GetType().Fullname
Write-Output "Output of $cmd"
Write-Output "============================================================"
Write-Output $data
Write-Output "============================================================"
clean_data $data
Write-Output $newdata
Remove-Job -Id $jobid.Id

OUTPUT

Data Type:
System.Object[]
Output of C:\opcragt.bat servername
============================================================

C:\Windows\system32>"D:\Program Files\HP\HP BTO Software\bin\win64\opcragt.cmd" servername


Node: servername
HPOM Managed Node status:
-------------------------
OV Performance Core coda (3500) is running
OV Communication Broker ovbbccb (10988) is running
OV Control ovcd (10400) is running
OV Config and Deploy ovconfd (5092) is running

Subagent EA:
Action Agent opcacta (9716) is running
Monitor Agent opcmona (9872) is running
Message Agent opcmsga (14712) is running
Message Interceptor opcmsgi (13512) is running
WMI Interceptor opcwbemi (6608) is running

**************************************************
Remote administration completed successfully on all nodes.

============================================================
Received data
Current
-------
Cleaning data

Keith Hill · Accepted Answer · 2012-10-23 21:36:00Z

8

Careful, $input is an automatic variable used by PowerShell to allow iteration over data passed into a function. Try this instead:

function clean_data($data) {
  Write-Verbose "Received data: $data"
  Write-Verbose "Cleaning data"
  $output = @()
  foreach ($line in $data) {
     Write-Verbose "Processing line: $line"
     if ($line -match 'running') {
          $output += $line
     }
   }
   $output
}

edited Oct 23, 2012 at 21:36

answered Oct 23, 2012 at 21:12

Keith Hill

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1 Comment

Marcus Grosz Over a year ago

LOL. I knew it had to be something simple. Either I haven't gotten to the chapter on automatic variables yet or the book I'm reading doesn't cover it. At any rate, thanks so much for the help. It works as I want it to now.

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