systemd is a suite of basic building blocks for a Linux system. It runs as PID 1 and is the system and service manager that bootstraps the rest of the userspace, supervises long-running services, and exposes a coordinated set of D-Bus and Varlink IPC interfaces for managing services (systemd1), users and sessions (logind), network interfaces (networkd), name resolution (resolved), containers/VMs (machined), home directories (homed), boot entries (boot1/sysupdate1), system hostname/locale/timedate, OOM protection (oomd), portable services, and image imports. The project also publishes a stable command-line surface (systemctl, journalctl, networkctl, resolvectl, loginctl, machinectl, hostnamectl, timedatectl, localectl, busctl, varlinkctl, bootctl, homectl, coredumpctl, oomctl, portablectl, importctl, systemd-analyze and more). systemd is dual-licensed (LGPL-2.1-or-later for libraries and most code, GPL-2.0-or-later for select tools) and developed openly on GitHub at systemd/systemd.
APIs.json: https://raw.githubusercontent.com/api-evangelist/systemd/refs/heads/main/apis.yml
- Type: Index
- Position: Consumer
- Access: 3rd-Party
- Boot
- Cgroups
- Container
- D-Bus
- Init
- IPC
- Journal
- Linux
- Logging
- Network
- Open Source
- PID 1
- Service Manager
- System
- Systemd
- Varlink
- Created: 2026-05-23
- Modified: 2026-05-23
Core D-Bus API exposed by PID 1 on the system bus. The Manager object at /org/freedesktop/systemd1 enumerates and controls units (services, sockets, mounts, targets, timers, paths, slices, scopes, swaps, devices), starts and stops jobs, loads/reloads configuration, manages cgroup-backed transient units, and emits lifecycle signals (UnitNew, UnitRemoved, JobNew, JobRemoved, Reloading, StartupFinished). Per-unit interfaces (Unit, Service, Socket, Mount, Slice, Scope, Path, Swap, Timer, Target) expose state, properties, and operations on individual units.
- Human URL: https://www.freedesktop.org/software/systemd/man/latest/org.freedesktop.systemd1.html
- Base URL:
dbus:org.freedesktop.systemd1
- Cgroups
- D-Bus
- Service Manager
- Systemd
- Units
- Documentation
- Interface Definition
- OpenAPI — OpenAPI Specification
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
D-Bus API of systemd-logind for tracking user logins, seats, sessions, and inhibitor locks. Manages session creation, switching, idle hints, lock/unlock, power-button handling, lid-switch handling, suspend/hibernate/reboot/power-off operations, and ACLs for hot-pluggable devices.
- Human URL: https://www.freedesktop.org/software/systemd/man/latest/org.freedesktop.login1.html
- Base URL:
dbus:org.freedesktop.login1
- D-Bus
- Logind
- Sessions
- Users
- Documentation
- Interface Definition
- OpenAPI — OpenAPI Specification
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
D-Bus API of systemd-networkd for managing network interfaces, link configuration, DHCP server state, and netdev/network unit reload. Exposes Manager and per-Link interfaces with methods to set link properties, reconfigure, force renew, and query link state.
- Human URL: https://www.freedesktop.org/software/systemd/man/latest/org.freedesktop.network1.html
- Base URL:
dbus:org.freedesktop.network1
- D-Bus
- DHCP
- Network
- Networkd
- Documentation
- Interface Definition
- OpenAPI — OpenAPI Specification
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
D-Bus API of systemd-resolved for DNS/mDNS/LLMNR resolution, DNSSEC validation, per-link DNS configuration, search domain management, DNS-over-TLS settings, and cache flushing. Exposes ResolveHostname, ResolveAddress, ResolveRecord, ResolveService and per-Link configuration methods.
- Human URL: https://www.freedesktop.org/software/systemd/man/latest/org.freedesktop.resolve1.html
- Base URL:
dbus:org.freedesktop.resolve1
- D-Bus
- DNS
- DNSSEC
- Resolved
- Documentation
- Interface Definition
- OpenAPI — OpenAPI Specification
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
D-Bus API of systemd-machined for tracking and managing local containers and virtual machines, enumerating their associated images, opening shells/login sessions inside them, copying files in/out, and binding mounts across container boundaries.
- Human URL: https://www.freedesktop.org/software/systemd/man/latest/org.freedesktop.machine1.html
- Base URL:
dbus:org.freedesktop.machine1
- Containers
- D-Bus
- Machined
- VMs
- Documentation
- Interface Definition
- OpenAPI — OpenAPI Specification
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
D-Bus API of systemd-hostnamed for getting and setting the system hostname (static, transient, pretty), deployment/location/icon metadata, chassis type, and machine info.
- Human URL: https://www.freedesktop.org/software/systemd/man/latest/org.freedesktop.hostname1.html
- Base URL:
dbus:org.freedesktop.hostname1
- D-Bus
- Hostname
- Hostnamed
- Documentation
- Interface Definition
- OpenAPI — OpenAPI Specification
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
D-Bus API of systemd-localed for getting and setting the system locale, X11 keymap, and console keymap.
- Human URL: https://www.freedesktop.org/software/systemd/man/latest/org.freedesktop.locale1.html
- Base URL:
dbus:org.freedesktop.locale1
- D-Bus
- Locale
- Localed
- Documentation
- Interface Definition
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
D-Bus API of systemd-timedated for getting and setting the system time, timezone, NTP enablement, and RTC-in-local-time policy.
- Human URL: https://www.freedesktop.org/software/systemd/man/latest/org.freedesktop.timedate1.html
- Base URL:
dbus:org.freedesktop.timedate1
- D-Bus
- NTP
- Time
- Timedated
- Documentation
- Interface Definition
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
D-Bus API of systemd-timesyncd exposing the current NTP server, peers, root delay/dispersion, and synchronization status.
- Human URL: https://www.freedesktop.org/software/systemd/man/latest/org.freedesktop.timesync1.html
- Base URL:
dbus:org.freedesktop.timesync1
- D-Bus
- NTP
- SNTP
- Timesyncd
- Documentation
- Interface Definition
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
D-Bus API of systemd-homed for managing portable, encrypted user home directories (LUKS, btrfs subvol, fscrypt, CIFS, directory) including create/remove/update/list operations, activation, authentication, and rebalancing.
- Human URL: https://www.freedesktop.org/software/systemd/man/latest/org.freedesktop.home1.html
- Base URL:
dbus:org.freedesktop.home1
- D-Bus
- Home Directories
- Homed
- LUKS
- Documentation
- Interface Definition
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
D-Bus API of systemd-importd for importing, exporting, downloading, listing, and removing container/VM machine images (tar, raw, dkr/OCI, qcow2) used by machined and portable services.
- Human URL: https://www.freedesktop.org/software/systemd/man/latest/org.freedesktop.import1.html
- Base URL:
dbus:org.freedesktop.import1
- Containers
- D-Bus
- Images
- Importd
- Documentation
- Interface Definition
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
D-Bus API of systemd-oomd, the userspace out-of-memory killer that uses cgroup v2 PSI signals to kill cgroups under memory or swap pressure. Exposes per-slice/cgroup state and policy.
- Human URL: https://www.freedesktop.org/software/systemd/man/latest/org.freedesktop.oom1.html
- Base URL:
dbus:org.freedesktop.oom1
- Cgroups
- D-Bus
- OOM
- Oomd
- PSI
- Documentation
- Interface Definition
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
D-Bus API of systemd-portabled for attaching/detaching portable service images, listing attached images, inspecting them, and managing their lifecycle on the host.
- Human URL: https://www.freedesktop.org/software/systemd/man/latest/org.freedesktop.portable1.html
- Base URL:
dbus:org.freedesktop.portable1
- D-Bus
- Portable Services
- Portabled
- Documentation
- Interface Definition
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
D-Bus API of systemd-sysupdated for transactional A/B updates of system/host/portable/container images using systemd-sysupdate transfers, including target enumeration, version listing, and update jobs.
- Human URL: https://www.freedesktop.org/software/systemd/man/latest/org.freedesktop.sysupdate1.html
- Base URL:
dbus:org.freedesktop.sysupdate1
- A/B Updates
- D-Bus
- Sysupdated
- System Updates
- Documentation
- Interface Definition
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
Generic D-Bus interface that systemd daemons (and other services) implement to expose runtime log level and log target configuration. Allows tools like systemd-analyze to change verbosity without restart.
- Human URL: https://www.freedesktop.org/software/systemd/man/latest/org.freedesktop.LogControl1.html
- Base URL:
dbus:org.freedesktop.LogControl1
- D-Bus
- Logging
- Observability
- Documentation
- Interface Definition
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
- Postman Collection — Postman Collection 2.1
- Open Collection — Open Collection 1.0
Modern JSON-line IPC surface exposed by systemd daemons via Varlink (single-fd, self-describing,
discoverable through varlinkctl). Covers ~39 interfaces including io.systemd.Manager, io.systemd.Unit,
io.systemd.Job, io.systemd.Login, io.systemd.Machine, io.systemd.Machine.Image,
io.systemd.MachineInstance, io.systemd.VirtualMachineInstance, io.systemd.Network,
io.systemd.Network.Link, io.systemd.Resolve, io.systemd.Resolve.Hook, io.systemd.Resolve.Monitor,
io.systemd.Journal, io.systemd.JournalAccess, io.systemd.Hostname, io.systemd.BootControl,
io.systemd.Credentials, io.systemd.FactoryReset, io.systemd.Import, io.systemd.InstanceMetadata,
io.systemd.AskPassword, io.systemd.Metrics, io.systemd.ManagedOOM, io.systemd.MountFileSystem,
io.systemd.MuteConsole, io.systemd.NamespaceResource, io.systemd.PCRExtend, io.systemd.PCRLock,
io.systemd.Repart, io.systemd.Shutdown, io.systemd.StorageProvider, io.systemd.Udev,
io.systemd.UserDatabase, io.systemd.oom, io.systemd.oom.Prekill, io.systemd.service, io.systemd.sysext.
- Human URL: https://systemd.io/USER_GROUP_API/
- Base URL:
varlink:io.systemd
- IPC
- JSON
- Varlink