% is better than $ because of shell escaping and confusion with shell
variables.
+Can we combine this with ability to set and read environment
+variables? Currently guestfish uses many environment variables like
+$EDITOR without any corresponding ability to set them.
+
+ set EDITOR /usr/bin/emacs
+ echo $EDITOR # or %{EDITOR}
+ edit /etc/resolv.conf
+
live CD inspection
------------------