systemd is the new system and service manager
in Oracle Linux 7 that replaces the Upstart
init daemon while providing backward
compatibility for legacy Oracle Linux 6 service scripts.
systemd offers the following benefits over
init:
Services are started in parallel wherever possible using socket-based activation and D-Bus.
Daemons can be started on demand.
Processes are tracked using control groups (cgroups).
Snapshotting of the system state and restoration of the system state from a snapshot is supported.
mount points can be configured as
systemdtargets.
systemd is the first process that starts after
the system boots, and is the final process that is running when
the system shuts down. systemd controls the
final stages of booting and prepares the system for use.
systemd also speeds up booting by loading
services concurrently.
systemd allows you to manage various types of
units on a system, including services
(name.service) and
targets
(name.target),
devices
(name.device), file
system mount points
(name.mount), and
sockets
(name.socket). For
example, the following command instructs the system to mount the
temporary file system (tmpfs) on
/tmp at boot time:
# systemctl enable tmp.mount