Powershell: Issue with & in scriptblock - powershell

Question

I face an issue when I run the following command
$x = "c:\Scripts\Log3.ps1"
$remoteMachineName = "172.16.61.51"
Invoke-Command -ComputerName $remoteMachineName -ScriptBlock {& $x}
The expression after '&' in a pipeline element produced an invalid object. It must result in a command name, script
block or CommandInfo object.
+ CategoryInfo : InvalidOperation: (:) [], RuntimeException
+ FullyQualifiedErrorId : BadExpression
+ PSComputerName : 172.16.61.51
Issue is not seen if I dont use $x variable
Invoke-Command -ComputerName $remoteMachineName -ScriptBlock {& 'c:\scripts\log3.ps1'}
Directory: C:\scripts
Mode LastWriteTime Length Name PSComputerName
---- ------------- ------ ---- --------------
-a--- 7/25/2013 9:45 PM 0 new_file2.txt 172.16.61.51

Answer 1

Variables in your PowerShell session are not transferred to sessions created with Invoke-Command
You need to use the -ArgumentList parameter to send the variables your command and then use the $args array to access them in the script block so your command will look like:
Invoke-Command -ComputerName $remoteMachineName -ScriptBlock {& $args[0]} -ArgumentList $x

Answer 2

If you work with variables inside a script block you need to add the modifier using:. Otherwise Powershell would search for the var definition inside the script block.
You can use it also with the splatting technique. E.g.:#using:params
Like this:
# C:\Temp\Nested.ps1
[CmdletBinding()]
Param(
[Parameter(Mandatory=$true)]
[String]$Msg
)
Write-Host ("Nested Message: {0}" -f $Msg)
# C:\Temp\Controller.ps1
$ScriptPath = "C:\Temp\Nested.ps1"
$params = #{
Msg = "Foobar"
}
$JobContent= {
& $using:ScriptPath #using:params
}
Invoke-Command -ScriptBlock $JobContent -ComputerName 'localhost'