<para>If invoked with no arguments, it operates on the block device backing the root file system partition

of the OS, thus growing and adding partitions of the booted OS image itself. When called in the initial

RAM disk it operates on the block device backing <filename>/sysroot/</filename> instead, i.e. on the

block device the system will soon transition into. The <filename>systemd-repart.service</filename>

service is generally run at boot in the initial RAM disk, in order to augment the partition table of the

OS before its partitions are mounted. <command>systemd-repart</command> (mostly) operates in a purely

incremental mode: it only grows existing and adds new partitions; it does not shrink, delete or move

existing partitions. The service is intended to be run on every boot, but when it detects that the

partition table already matches the installed <filename>repart.d/*.conf</filename> configuration

files, it executes no operation.</para>

<filename>repart.d/*.conf</filename> files and for the machine ID file to use as seed. By default

when invoked on the regular system this defaults to the host's root file system