Filter AppCmd to running sites

I have a script that uses appcmd to find sites using a particular vdir and iterates through them to find which ones are currently running

appcmd.exe list vdir /physicalPath:Z:\My\Path
:: save sites to array

:: foreach SiteName in array
appcmd.exe list site SiteName
:: hunt for "Started" in the output

but I would like to directly filter down to running sites using said virtual directory. I have expectations that there's a /parameter:value that does exactly that, but I can't seem to find a list of possible parameters.

• Best would be arguments on the list vdir call that render the list site unnecessary.

• Second best would be a filter on the list site call that removes the need to hunt for "Started"

• If there is a (complete) list of appcmd parameters on MSDN, TechNet, or somewhere that proves this is not possible, that would also be helpful.