Writing systemd Units
Systemd has become the defacto new standard init for Linux-based systems. While not everyone has made the switch yet, pretty much all the major distros have made the decision to switch.
For most people this has not meant all that much yet, other than a lot of controversy. Systemd has built in SysV init system compatibility, and so it's possible to avoid dealing with it quite well. But there is much to be gained from picking up some basics. Systemd is very poweful.
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