Systemd

Systemd is slowly becoming the emerging standard for init. If you have a /usr/lib/systemd directory, you're most likely using systemd.

Systemd uses goals to get your system up and running. Basically you have a target that you want to achieve and this target also has dependencies that we need to achieve. Systemd is extremely flexible and robust, it does not follow a strict sequence to get processes started. Here's what happens during the typical systemd boot:

First, systemd loads its configuration files, usually located in /etc/systemd/system or /usr/lib/systemd/system
Then it determines its boot goal, which is usually default.target
Systemd figures out the dependencies of the boot target and activates them

List units

$ systemctl list-units

View status of unit

$ systemctl status networking.service

Start a service

$ sudo systemctl start networking.service

Stop a service

$ sudo systemctl stop networking.service

Restart a service

$ sudo systemctl restart networking.service

Enable a unit

$ sudo systemctl enable networking.service

Disable a unit

$ sudo systemctl disable networking.service