Global scope variable is null within Scriptblock

Question

Running the following code produces an error because the variable used for path is resolved as null event though it defined in the script:

$ServerName = "test01"
$RemotePath = "C:\Test\"
$TestScriptBlock = { copy-item -Path $RemotePath  -Destination C:\backup\ -Force -Recurse } 
$CurrentSession = New-PSSession -ComputerName $ServerName

Invoke-Command -Session $CurrentSession -ScriptBlock $TestScriptBlock

How do I call the $RemotePath defined in the parent script from within the ScriptBlock? I need to use $RemotePath in other parts of the parent script. Note, this value doesn't change, so it can be a constant.

UPDATE -- WORKING SOLUTION

You have to pass in variable as parameter to the scriptblock:

$ServerName = "test01"
$RemotePath = "C:\Test\"
$TestScriptBlock = { param($RemotePath) copy-item -Path $RemotePath  -Destination C:\backup\ -Force -Recurse } 
$CurrentSession = New-PSSession -ComputerName $ServerName

Invoke-Command -Session $CurrentSession -ScriptBlock $TestScriptBlock -ArgumentList $RemotePath

use can try using $global:RemotePath = "C:\Test\" as global variable which can be accessed anywhere in entire script file — Nipun, Jul 16 '14 at 12:03

score 3 · Accepted Answer · answered Jul 16 '14 at 11:52

3

You've got two scripts there, not one. The $TestScriptBlock is a separate script nested inside the main one, you send it to the remote computer, and that remote computer doesn't have $RemotePath configured. Try:

$ServerName = "test01"

$TestScriptBlock = {
    $RemotePath = "C:\Test\"
    copy-item -Path $RemotePath  -Destination C:\backup\ -Force -Recurse 
}

$CurrentSession = New-PSSession -ComputerName $ServerName

Invoke-Command -Session $CurrentSession -ScriptBlock $TestScriptBlock

(I would probably call it $LocalPath then, though)

answered Jul 16 '14 at 11:52

TessellatingHeckler

27,511
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Anyway of having a defining one global variable within this parent script so that I can use it in both the scriptblock and the parent script? Otherwise I'll need to have duplicate variables to maintain in the script because I need to use it in other locations outside of the script block. Note, this value doesn't change, so it can be a constant. – Jul 16 '14 at 11:55
Yes maybe although I haven't tried - http://powershell.com/cs/blogs/tips/archive/2012/10/26/executing-code-locally-and-remotely-using-local-variables.aspx seems like it would help. – TessellatingHeckler Jul 16 '14 at 12:08
I got it to work thanks to your link in your comment. I'll add an update above so that others can see the solution. Thanks. – Jul 16 '14 at 12:25

score 2 · Answer 2 · edited Oct 22 '20 at 14:57

2

Try this syntax:

$globalvariable1 = "testoutput01"
$globalvariable2 = "testoutput02"

$Scriptblock = {
    Write-Host $using:globalvariable1
    Write-Host $using:globalvariable2
}

$serverName = Domain\HostNameofServer

Invoke-Command -ComputerName $serverName -ScriptBlock $ScriptBlock -ArgumentList $globalvariable1, $globalvariable2

edited Oct 22 '20 at 14:57

Elijan9

1,269
2
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answered Oct 22 '20 at 09:20

santoshKalaiselvan

21
1

score 0 · Answer 3 · edited May 23 '17 at 10:29

0

The execution happens in a different session and all the variables in the current scope are not copied to the remote session by default. You can use either parameters or "using:" as explained here:

How can I pass a local variable to a script block executed on a remote machine with Invoke-Command?

edited May 23 '17 at 10:29

Community

1
1

answered Dec 12 '16 at 02:15

jonatasmello

86
1
5

Global scope variable is null within Scriptblock

3 Answers3