Powershell referencing current directory and subfolder - powershell

Question

I use the following code to reference files in the current script directory
$PSScriptRoot = Split-Path -Parent -Path $MyInvocation.MyCommand.Definition
Then I can call it like
try {
WriteLog("Installing...")
$installresult = (Start-Process msiexec.exe -ArgumentList "/i
$PSScriptRoot\InstallPrism6.msi /qn /norestart" -Wait -PassThru).ExitCode
WriteLog("Installation finished with return code: $installresult")
}
catch {
WriteLog($_.Exception.Message)
}
This works fine. However, if I want to reference a file in a subdirectory like so
try {
WriteLog("Installing...")
$installresult = (Start-Process msiexec.exe -ArgumentList "/i $PSScriptRoot
+ \test\InstallPrism6.msi /qn /norestart" -Wait -PassThru).ExitCode
WriteLog("Installation finished with return code: $installresult")
}
catch {
WriteLog($_.Exception.Message)
}
it fails with error code 1639.
If this doesn't work, how can I reference subdirectories when using $PSScriptRoot?

Answer 1

Note that the $PSScriptRoot variable is predefined on PowerShell 3.0 and newer, so you only need that variable if it's not already defined. I believe the proper syntax for what you want to do should look like the following:
if ( -not $PSScriptRoot ) {
$PSScriptRoot = Split-Path $MyInvocation.MyCommand.Path -Parent
}
try {
WriteLog "Installing..."
$installresult = (Start-Process msiexec.exe -ArgumentList "/i","`"$PSScriptRoot\test\InstallPrism6.msi`"","/qn","/norestart" -Wait -PassThru).ExitCode
WriteLog "Installation finished with return code: $installresult"
}
catch {
WriteLog $_.Exception.Message
}
-ArgumentList is technically an array, and I embedded the " in case the path contains any whitespace.

Answer 2

Try not leaving spaces in your path. When you are building a string using a variable, you don't need to concatenate. It's not about referencing subfolders.
try {
WriteLog("Installing...")
$installresult = (Start-Process msiexec.exe -ArgumentList "/i ${PSScriptRoot}\test\InstallPrism6.msi /qn /norestart" -Wait -PassThru).ExitCode
WriteLog("Installation finished with return code: $installresult")
}
catch {
WriteLog($_.Exception.Message)
}