SysV

Runs scripts in /etc/init.d

runlevels

Part of SystemV, in /etc/rc.d/, based on the distro you have folders or files defining each runlevel

Systemd

systemd is a suite of basic building blocks for service management.

systemd diagram

Upstart

Used on Ubuntu by default

Launchd

Used on macOS

TODO

runit -- TODO

is an init scheme for unix-like operating systems.

Daemon

Back to Unix

systemd Unit Files -- source

.service files, in /usr/lib/systemd/system/ have unit types:

Basic service:

[Unit]
Description=Foo

[Service]
ExecStart=/usr/sbin/foo-daemon