Pass arguments to a scriptblock in powershell - powershell

Question

I guess you can't just do this:
$servicePath = $args[0]
if(Test-Path -path $servicePath) <-- does not throw in here
$block = {
write-host $servicePath -foreground "magenta"
if((Test-Path -path $servicePath)) { <-- throws here.
dowork
}
}
So how can I pass my variables to the scriptblock $block?

Answer 1

Keith's answer also works for Invoke-Command, with the limit that you can't use named parameters. The arguments should be set using the -ArgumentList parameter and should be comma separated.
$sb = {
param($p1,$p2)
$OFS=','
"p1 is $p1, p2 is $p2, rest of args: $args"
}
Invoke-Command $sb -ArgumentList 1,2,3,4
Also see here and here.

Answer 2

A scriptblock is just an anonymous function. You can use $args inside the
scriptblock as well as declare a param block, for example
$sb = {
param($p1, $p2)
$OFS = ','
"p1 is $p1, p2 is $p2, rest of args: $args"
}
& $sb 1 2 3 4
& $sb -p2 2 -p1 1 3 4

Answer 3

BTW, if using the script block to run in a separate thread (multi threaded):
$ScriptBlock = {
param($AAA,$BBB)
return "AAA is $($AAA) and BBB is $($BBB)"
}
$AAA = "AAA"
$BBB = "BBB1234"
$null = Start-Job $ScriptBlock -ArgumentList $AAA,$BBB
then yields:
$null = Start-Job $ScriptBlock -ArgumentList $AAA,$BBB
Get-Job | Receive-Job
AAA is AAA and BBB is BBB1234

Answer 4

For anyone reading in 2020 who wants to use local variables in a remote session script block, starting in Powershell 3.0 you can use local variables directly in the scriptblock with the "$Using" scope modifier. Example:
$MyLocalVariable = "C:\some_random_path\"
acl = Invoke-Command -ComputerName REMOTEPC -ScriptBlock {Get-Acl $Using:MyLocalVariable}
Found in example 9 of https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.core/invoke-command?view=powershell-7

Answer 5

By default PowerShell won't capture variables for a ScriptBlock. You can explicitly capture by calling GetNewClosure() on it, however:
$servicePath = $args[0]
if(Test-Path -path $servicePath) <-- does not throw in here
$block = {
write-host $servicePath -foreground "magenta"
if((Test-Path -path $servicePath)) { <-- no longer throws here.
dowork
}
}.GetNewClosure() <-- this makes it work

Answer 6

Three example syntax:
$a ={
param($p1, $p2)
"p1 is $p1"
"p2 is $p2"
"rest of args: $args"
}
//Syntax 1:
Invoke-Command $a -ArgumentList 1,2,3,4 //PS> "p1 is 1, p2 is 2, rest of args: 3 4"
//Syntax 2:
&$a -p2 2 -p1 1 3 //PS> "p1 is 1, p2 is 2, rest of args: 3"
//Syntax 3:
&$a 2 1 3 //PS> "p1 is 2, p2 is 1, rest of args: 3"

Answer 7

I know this article is a bit dated, but I wanted to throw this out as a possible alternative. Just a slight variation of the previous answers.
$foo = {
param($arg)
Write-Host "Hello $arg from Foo ScriptBlock" -ForegroundColor Yellow
}
$foo2 = {
param($arg)
Write-Host "Hello $arg from Foo2 ScriptBlock" -ForegroundColor Red
}
function Run-Foo([ScriptBlock] $cb, $fooArg){
#fake getting the args to pass into callback... or it could be passed in...
if(-not $fooArg) {
$fooArg = "World"
}
#invoke the callback function
$cb.Invoke($fooArg);
#rest of function code....
}
Clear-Host
Run-Foo -cb $foo
Run-Foo -cb $foo
Run-Foo -cb $foo2
Run-Foo -cb $foo2 -fooArg "Tim"

Answer 8

Other possibility:
$a ={
param($p1, $p2)
"p1 is $p1"
"p2 is $p2"
"rest of args: $args"
};
$a.invoke(1,2,3,4,5)