/var

/var

/var

/var

/etc

/etc

/etc/passwd

/etc/group

/etc

Booting up a system without a populatedis relatively straight-forward. With a few lines of tmpfiles configuration it is possible to populatewith its basic structure in a way that is sufficient to make a system boot cleanly. systemd version 214 and newer ship with support for this. Of course, support for this scheme in systemd is only a small part of the solution. While a lot of software reconstructs the directory hierarchy it needs inautomatically, many software does not. In case like this it is necessary to ship a couple of additional tmpfiles lines that setup up at boot-time the necessary files or directories into make the software operate, similar to what RPM or DEB packages would set up at installation time. Booting up a system without a populatedis a more difficult task. Inwe have a lot of configuration bits that are essential for the system to operate, for example and most importantly system user and group information inand. If the system boots up withoutthere must be a way to replicate the minimal information necessary in it, so that the system manages to boot up fully.