The new FAI version 5.5 supports a very nice feature in fcopy. Using -S, fcopy itself can do variable substitution, which may replace your preinst scripts. Until now preinst scripts for fcopy were used for doing variable substitution. We also got rid of the need to have aptitude installed.
More details can be found in the Changelog https://github.com/faiproject/fai/blob/master/debian/changelog I've already created new FAI CD images that are available at https://fai-project.org/fai-cd/ Currently I'm very busy working on a brand new FAI feature, which will be announced in a couple of weeks. -- regards Thomas