Restart script as admin and preserve switch and string parameters - powershell

Question

I'm writing a PowerShell script that uses parameters / arguments and needs to be run as administrator but I'm trying to make it as user-friendly as possible so I'm trying to write it so that if it wasn't run as administrator then it can auto-elevate itself and preserve the original parameters (only switches and strings).
I was not able to find a solution online, hence this post.

Answer 1

I managed to accomplish this by "stringifying" $PsBoundParameters then using that with Start-Process PowerShell -Verb Runas -ArgumentList.
Note: $PsBoundParameters uses the parameters of the current scope ("root" vs inside a function, for example) so if you need to reference the command-line parameters (as I do) then you'll need to either use this variable outside of a function or first pass the variable to the function (as I've done here).
I've created a demonstration of this:
Param(
[switch]$ExampleSwitch,
[string]$ExampleString
)
Function Restart ($AllParameters, $Admin) {
$AllParameters_String = "";
ForEach ($Parameter in $AllParameters.GetEnumerator()){
$Parameter_Key = $Parameter.Key;
$Parameter_Value = $Parameter.Value;
$Parameter_Value_Type = $Parameter_Value.GetType().Name;
If ($Parameter_Value_Type -Eq "SwitchParameter"){
$AllParameters_String += " -$Parameter_Key";
} Else {
$AllParameters_String += " -$Parameter_Key $Parameter_Value";
}
}
$Arguments = "-File `"" + $PSCommandPath + "`" -NoExit" + $AllParameters_String;
If ($Admin -Eq $True){
Start-Process PowerShell -Verb Runas -ArgumentList $Arguments;
} Else {
Start-Process PowerShell -ArgumentList $Arguments;
}
}
$RanAsAdministrator = ([Security.Principal.WindowsPrincipal] [Security.Principal.WindowsIdentity]::GetCurrent()).IsInRole([Security.Principal.WindowsBuiltInRole]::Administrator);
Write-Host "ExampleSwitch value:" $ExampleSwitch;
Write-Host "ExampleString value:" $ExampleString;
Write-Host "";
If ($RanAsAdministrator -Eq $True){
Write-Host "Running as administrator: Yes.";
} Else {
Write-Host "Running as administrator: No.";
}
$Elevate = Read-Host "Restart as current user or admin? (u/a)";
Write-Host "";
If ($Elevate -Like "u"){
Restart $PsBoundParameters;
} ElseIf ($Elevate -Like "a") {
Restart $PsBoundParameters -Admin $True;
}
Start-Sleep -Seconds 9999;

Answer 2

Param(
[Switch]$MySwitch,
[String]$MyString,
[Switch]$NoExit
)
If (!([Security.Principal.WindowsPrincipal][Security.Principal.WindowsIdentity]::GetCurrent()).IsInRole([Security.Principal.WindowsBuiltInRole] "Administrator")) {
$PSHost = If ($PSVersionTable.PSVersion.Major -le 5) {'PowerShell'} Else {'PwSh'}
Start-Process -Verb RunAs $PSHost (#(' -NoExit')[!$NoExit] + " -File `"$PSCommandPath`" " + ($MyInvocation.Line -split '\.ps1[\s\''\"]\s*', 2)[-1])
Break
}
Write-Host "MySwitch:" $MySwitch;
Write-Host "MyString:" $MyString;
Explanation:
($MyInvocation.Line -split '\.ps1[\s\''\"]\s*', 2)[-1]) will resolve the current parameters
$MyHost determines the current PowerShell Host (PowerShell for Windows or PowerShell Core) and use the same host for the elevated window.
The -NoExit switch will prevent the elevated window to automatically close
Example:
.\RunAsAdministrator.ps1 -MyString "Test 123" -MySwitch -NoExit