systemd-userdbd.service - Man Page

systemd-userdbd​.service

/usr/lib/systemd/systemd-userdbd

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) manpage​.

Most of systemd-userdbd's functionality is accessible through the userdbctl(1) 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​.

systemd(1), nss-systemd(8), userdbctl(1), systemd-homed.service(8)

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/

nss-systemd(8), systemd.directives(7), systemd.index(7), systemd.system-credentials(7), userdbctl(1).

The man page systemd-userdbd(8) is an alias of systemd-userdbd.service(8).