Using Invoke-Command -ScriptBlock on a function with arguments

Question

I'm writing a PowerShell script that will execute commands on a remote host using Invoke-Command and its -ScriptBlock parameter. For example,

function Foo {
    ...
    return "foo"
}
$rv = Invoke-Command --Credential $c --ComputerName $fqdn -ScriptBlock ${function:Foo}

This works fine. What I'd like to do now is the same thing, but call a function with local arguments. For example,

function Bar {
    param( [String] $a, [Int] $b )
    ...
    return "foo"
}
[String] $x = "abc"
[Int] $y = 123
$rv = Invoke-Command --Credential $c --ComputerName $fqdn -ScriptBlock ${function:Foo($x,$y)}

But this does not work:

Invoke-Command : Cannot validate argument on parameter 'ScriptBlock'. The argument is null. Supply a non-null argument and try the command again.

How can I use Invoke-Command with a -ScriptBlock that is a local function with arguments?

I realize that I can wrap the entire function and the parameters in a big code block, but that is not a clean way of doing it, in my opinion.

manojlds · Accepted Answer · 2011-12-09 17:17:51Z

53

I think you want:

function Foo ( $a,$b) {
    $a
    $b
    return "foo"
}

$x = "abc"
$y= 123

Invoke-Command -Credential $c -ComputerName $fqdn -ScriptBlock ${function:Foo} -ArgumentList $x,$y

answered Dec 9, 2011 at 17:17

manojlds

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9 Comments

Christopher Neylan Over a year ago

thanks man, works perfectly! I was messing with combos of param() + -Arguments with no luck.

icnivad Over a year ago

took me several hours to find this solution ;-) Much better than exporting/importing sessions Thank You!

MorayM Over a year ago

I believe the correct format should be -ScriptBlock {$function:Foo} (note $ position)

DarkLite1 Over a year ago

I tried it out and this is the only way that it works ${function:Foo}. At least when you have the format ${function:Foo-Bar}.

nohwnd Over a year ago

There is big difference between {$function:Foo} and ${function:Foo}. The curly braces in the former mean scriptblock, and so the expression means: "A scriptblock that resolves to variable foo in function scope." The curly braces in the latter mean the the name of the variable is taken literarly and so it translates simply to: "A variable foo in function scope." This would be useful if the "foo" variable had spaces or other special charactes in name.

|

reconbot · Accepted Answer · 2011-12-09 17:10:31Z

9

You can wrap the functions in a block and pass the block;

$a = {
  function foo{}
  foo($args)
}

$a.invoke() // Locally

$rv = Invoke-Command --Credential $c --ComputerName $fqdn -ScriptBlock $a //remotely

It's hardly elegant though.

answered Dec 9, 2011 at 17:10

reconbot

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Comments

8DH · Accepted Answer · 2012-10-15 12:49:29Z

2

This also works:

function foo
{
    param([string]$hosts, [string]$commands)
    $scriptblock = $executioncontext.invokecommand.NewScriptBlock($commands)
    $hosts.split(",") |% { Invoke-Command -Credential $cred -ComputerName $_.trim() -Scriptblock $scriptblock }
}

edited Oct 15, 2012 at 12:49

8DH

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answered Apr 10, 2012 at 16:12

prophesional

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Comments

levymtmr · Accepted Answer · 2022-04-18 14:50:33Z

-1

$Log = "PowerShellCore/Operational"

Invoke-Command -ComputerName Server01 -ScriptBlock {Get-WinEvent -LogName $Using:Log -MaxEvents 10}\

answered Apr 18, 2022 at 14:50

levymtmr

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