---
name: "systemd-userdbd.service"
section: "8"
platform: "linux"
package: "systemd"
version: "262.1-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/systemd-userdbd.service"
---

# systemd-userdbd.service(8)

JSON User/Group Record Query Multiplexer/NSS Compatibility

## NAME

systemd-userdbd.service, systemd-userdbd - JSON User/Group Record Query Multiplexer/NSS Compatibility

## SYNOPSIS

systemd-userdbd.service

/usr/lib/systemd/systemd-userdbd

## DESCRIPTION

**systemd-userdbd** is a system service that multiplexes user/group lookups to all local services that provide JSON user/group record definitions to the system. In addition it synthesizes JSON user/group records from classic UNIX/glibc NSS user/group records in order to provide full backwards compatibility. It may also pick up statically defined JSON user/group records from files in /etc/userdb/, /run/userdb/, /run/host/userdb/ and /usr/lib/userdb/ with the ".user" or ".group" extension. For more details about the extensions read the [**nss-systemd**(8)](/nss-systemd/8.md) manpage.

Most of **systemd-userdbd**'s functionality is accessible through the [**userdbctl**(1)](/userdbctl/1.md) command.

The user and group records this service provides access to follow the **JSON User Records**\[1\] and **JSON Group Record**\[2\] definitions. This service implements the **User/Group Record Lookup API via Varlink**\[3\], and multiplexes access other services implementing this API, too. It is thus both server and client of this API.

This service provides three distinct **Varlink**\[4\] services: **io.systemd.Multiplexer** provides a single, unified API for querying JSON user and group records. Internally it talks to all other user/group record services running on the system in parallel and forwards any information discovered. This simplifies clients substantially since they need to talk to a single service only instead of all of them in parallel. **io.systemd.NameServiceSwitch** provides compatibility with classic UNIX/glibc NSS user records, i.e. converts **struct passwd** and **struct group** records as acquired with APIs such as **getpwnam**(1) to JSON user/group records, thus hiding the differences between the services as much as possible. **io.systemd.DropIn** makes JSON user/group records from the aforementioned drop-in directories available.

## SEE ALSO

[**systemd**(1)](/systemd/1.md), [**nss-systemd**(8)](/nss-systemd/8.md), [**userdbctl**(1)](/userdbctl/1.md), [**systemd-homed.service**(8)](/systemd-homed.service/8.md)

## NOTES

- 1\.

  JSON User Records

  https://systemd.io/USER\_RECORD

- 2\.

  JSON Group Record

  https://systemd.io/GROUP\_RECORD

- 3\.

  User/Group Record Lookup API via Varlink

  https://systemd.io/USER\_GROUP\_API

- 4\.

  Varlink

  https://varlink.org/