3.1 About systemd

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 systemd targets.

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