I want to run "virsh update-device guest-name snippet.xml", for the moment from Cmd.cmdProperty. snippet.xml should contain the actual configuration information. I'm wondering what the best approach is. 1. create a persistent copy of this file using File.hasContent or similar 2. generate a temporary file when running the property. 3. Use a file from the propellor repo (1) is slightly gross because the persistent copy is used only when running propellor. (2) I don't really know how to do in propellor; I guess it has to do with monads. (3) I don't know if this will work or is frowned upon for some reason.