Variable Substitution inside a PowerShell Scriptblock run as Administrator - powershell

Question

I'm writing code in PowerShell. I want to change the port in a configuration file as administrator, but it doesn't work.
Here's my code:
$port=8888
$ScriptBlock = {
function bar($port) {
$config = Get-Content -Path "c:\Users\Me\foo.xml"
$NewConfig = $Config -replace 'httpPort=[0-9]*\s',"httpPort=$port "
Set-Content -Path c:\ProgramFiles(x86)\foo.xml -Value $NewConfig -Force
}
};
Start-Process -FilePath powershell.exe -ArgumentList $ScriptBlock,"bar('$port')" -Verb RunAs -Wait
I think its having trouble with the second part of the -replace ("httpPort=$port ").
What am I missing?

Answer 1

You can try the following:
Start-Process -Verb RunAs -Wait -FilePath powershell.exe -ArgumentList '-Command',
"$($ScriptBlock -replace '"', '\"'); bar $port"
As an aside:
* The regex you're using to match the port number suggests that it is an unquoted attribute value, which, while acceptable in HTML, is not well-formed XML.
* Don't invoke your function with method syntax (bar($port)) - PowerShell functions are called like shell commands, without parentheses and with arguments separated by whitespace rather than ,: bar $port
As for what you tried:
Start-Process invariably interprets the arguments passed to -ArgumentList as strings, and while a script block conveniently stringifies to its literal string content, you need to escape the embedded " chars. as \" (sic) in order for the target PowerShell instance to recognize them properly with the (implied in Windows PowerShell) -Command option.
Since -Command simply concatenates all subsequent arguments with a space as the separator before interpreting the resulting string as a piece of PowerShell source code, it is generally preferable to pass a single string, for conceptual clarity.