mirror of
https://pagure.io/fedora-docs/quick-docs.git
synced 2024-11-25 05:37:32 +00:00
51 lines
1.9 KiB
Text
51 lines
1.9 KiB
Text
[id='understanding-systemd']
|
|
= Understanding systemd
|
|
|
|
systemd is a system and service manager for Linux, compatible with SysV and LSB init scripts. systemd provides:
|
|
|
|
* Aggressive parallelization capabilities
|
|
* Uses socket and D-Bus activation for starting services
|
|
* Offers on-demand starting of daemons, keeps track of processes using Linux cgroups
|
|
* Supports snapshotting and restoring of the system state
|
|
* Maintains mount and automount points
|
|
* Implements an elaborate transactional dependency-based service control logic.
|
|
|
|
The `systemctl` command is the primary tool to manage systemd. It combines the functionality of SysVinit's `service` and `chkconfig` commands into a single tool you can use to enable and disable services permanently or only for the current session.
|
|
|
|
systemd manages _units_, which are representations of system resources and services. This following list shows the unit types that systemd can manage:
|
|
|
|
service::
|
|
A service on the system, including instructions for starting, restarting, and stopping the service.
|
|
|
|
socket::
|
|
A network socket associated with a service.
|
|
|
|
device::
|
|
A device specifically managed with systemd.
|
|
|
|
mount::
|
|
A mountpoint managed with systemd.
|
|
|
|
automount::
|
|
A mountpoint automatically mounted on boot.
|
|
|
|
swap::
|
|
Swap space on the system.
|
|
|
|
target::
|
|
A synchronization point for other units. Usually used to start enabled services on boot.
|
|
|
|
path::
|
|
A path for path-based activation. For example, you can start services based on the state of a certain path, such as whether it exists or not.
|
|
|
|
timer::
|
|
A timer to schedule activation of another unit.
|
|
|
|
snapshot::
|
|
A snapshot of the current systemd state. Usually used to rollback after making temporary changes to systemd.
|
|
|
|
slice::
|
|
Restriction of resources through Linux Control Group nodes (cgroups).
|
|
|
|
scope::
|
|
Information from systemd bus interfaces. Usually used to manage external system processes.
|