Although systemd has been the object of many controversies, to the point the some distributions were forked just to get rid of it (see Devuan, a fork of Debian which, by default, replaces systemd with sysvinit), in the end it has become the de-facto stand

For example, to define the various system states, the SysVinit uses numbers, known as run-levels, while the Systemd uses keywords, known as target-units. The SysVinit is a classic program that was used to manage the Linux system for several years. It has

/usr/lib/systemd/system/: Contains default systemd unit configurations as per contained in the rpm When looking for a unit, systemd searches the directories in that order, stopping as soon as it finds a match, allowing you to override the behavior of a di