why does a scriptblock passed as an argument in invoke-commands argumentlist fail?

Question

function test-scriptblock {
1..10 }
function caller ([scriptblock]$runthis) {
& $runthis
}

the following works fine.

caller -runthis ${function:test-scriptblock}

this doesn't work

invoke-command -ComputerName localhost -ScriptBlock ${function:caller} -ArgumentList ${function:test-scriptblock}

Cannot process argument transformation on parameter 'runthis'. Cannot convert the "
1..10 " value of type "System.String" to type "System.Management.Automation.ScriptBlock".
+ CategoryInfo          : InvalidData: (:) [], ParameterBindin...mationException
+ FullyQualifiedErrorId : ParameterArgumentTransformationError

participant · Accepted Answer · 2015-01-14 16:38:47Z

6

I verified that this a "known issue". While in most cases in remoting scriptblocks regurgitate just fine as scriptblocks but with ArgumentList they don't, so instead I do

function Caller($runthis)
{
   $runthis = [Scriptblock]::Create($runthis)
   &$runthis
}

edited Jan 14, 2015 at 16:38

participant

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answered Aug 24, 2011 at 19:37

klumsy

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Comments

manojlds · Accepted Answer · 2011-08-24 20:26:31Z

2

Since -ArgumentList takes in Object[], I think it is received by caller as a string. One workaround is this:

function caller ($runthis) {
$runthis = $executioncontext.InvokeCommand.NewScriptBlock($runthis)
& $runthis
}

Note that something like this works:

function caller ($runthis) {
$runthis  | kill
}

$p= Get-Process -name notepad
invoke-command -computer localhost -ScriptBlock ${function:caller} -ArgumentList $p

I think scriptblocks are treated differently since it might be considered a security issue to just run them.

edited Aug 24, 2011 at 20:26

answered Aug 24, 2011 at 19:34

manojlds

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Comments

JPBlanc · Accepted Answer · 2011-08-25 05:23:59Z

0

Adapted to your initial code, I do it so :

caller -runthis (get-item Function:\test-scriptblock).scriptblock

A function is not a scriptblock, a scriptblock is a property of a function.

answered Aug 25, 2011 at 5:23

JPBlanc

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2 Comments

manojlds Over a year ago

Doesn't really answer the question. The real problem is in passing it in ArgumentList

manojlds Over a year ago

I say that because even with scriptblock prop it doesn't work from ArgumentList.

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