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PowerShell script which executes a command for each line of a variable containing a list

Sorry but I am not a Powershell expert. And I want to modify a PowerShell script which executes a command for each line of a variable containing a list.

To make it all understandable, I will simplify my example (in the reality, that's for vmware scripting, but my problem concerns the Powershell syntax )

Imagine a list of computers, stored in a variable, result of another powershell command.
It might look like this.:
SERVERA
SERVERB
SERVERC
SERVERD

And It's stored in a variable "list_computers" ($list_computers)
I want for each computer some (powershell) commands to be executed.
For example

display the computername
ping the computername

How to do that?
How to read each line of the variable ?
Should I use Foreach of Foreach-Object?
How to execute several commands ?

NB:
command "write $list_computers" give:

SERVERA
SERVERB
SERVERC
SERVERD

Could the following syntax be correct?

$list_computers | foreach-object {
$computer = $_
write $computer
command1 $computer
command2 $computer
}

Thanks

Jm

footech

What you have in your variable is an array. Some example code to see this info:

$list_computers.GetType()

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Each individual item in an array is called an element. To see the type of each element you can call the GetType() method for an individual element, or pipe to the Get-Member cmdlet.

$list_computers[0].GetType()
$list_computers | Get-Member # this also shows the methods and properties available of the element type

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When you have an array stored in a variable you can use pretty much any of the various looping constructs to process each element one at a time. Looping constructs include the foreach statment, the ForEach-Object cmdlet, for, do-while, while, etc. Many times it doesn't matter which you use, though there may be some benefits to choosing one method over another in specific circumstances. However, suffice it to say that the ForEach-Object cmdlet is the one that you will likely use the most, and your syntax in the end is correct. Many times you don't have to assign the current item in the loop ( $_ ) to a variable, but it's very safe to do so.

Zvonko

Check this:

ForEach ($computer in $list_computers) { 
	Write-Host $computer 
	Test-Connection -ComputerName  $computer -Count 1 
	Test-Connection -ComputerName  $computer -Count 1 
}

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Zvonko

Or better try-catch:

ForEach ($computer in $list_computers) { 
	Write-Host $computer 
	Try { 
		Test-Connection -ComputerName  $computer -Count 1 -ErrorAction Stop 
		Test-Connection -ComputerName  $computer -Count 1 -ErrorAction Stop 
	} Catch { 
		Write-Host "$($computer) was not found: $($_.Exception.Message)" -ForegroundColor Green 
	} 
}

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Alptekin Keskin

below is for command prompt

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FOR /f %i IN (c:\TEMP\list.txt) DO ping %i

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for powershell

cmd /c 'FOR /f %i IN (c:\TEMP\list.txt) DO ping %i'

Zvonko

Sorry only one lookup/ping:

ForEach ($computer in $list_computers) { 
	Write-Host $computer 
	Try { 
		Test-Connection -ComputerName  $computer -Count 1 -ErrorAction Stop 
	} Catch { 
		Write-Host "$($computer) was not found: $($_.Exception.Message)" -ForegroundColor Green 
	} 
}

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Zvonko

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