PowerShell supports regular expressions in a lot of areas which is why the following code fails:
'c:\test\subfolder\file' -split '\'
Split expects a regular expression and fails when you use special characters like "\". To translate a plain text into an escaped regular expression text, try this:
[Regex]::Escape('\') \\
As you see, "\" is the RegEx escape character and therefore needs to be escaped:
'c:\test\subfolder\file' -split '\\' ('c:\test\subfolder\file' -split '\\')[-1]
