DESCRIPTION
       A daemon is a service process that runs in the background and supervises the system
       or provides functionality to other processes. Traditionally, daemons are implemented
       following a scheme originating in SysV Unix. Modern daemons should follow a simpler
       yet more powerful scheme (here called "new-style" daemons), as implemented by
       systemd(1). This manual page covers both schemes, and in particular includes
       recommendations for daemons that shall be included in the systemd init system.

If set to  forking , it is expected that the process configured with ExecStart=
will call fork() as part of its start-up. The parent process is expected to exit
when start-up is complete and all communication channels are set up. The child
continues to run as the main daemon process. This is the behavior of traditional
UNIX daemons. If this setting is used, it is recommended to also use the
PIDFile= option, so that systemd can identify the main process of the daemon.
systemd will proceed with starting follow-up units as soon as the parent process
exits.

Behavior of  oneshot  is similar to simple; however, it is expected that the
process has to exit before systemd starts follow-up units.  RemainAfterExit= is
particularly useful for this type of service. This is the implied default if
neither Type= or ExecStart= are specified.