NAME

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

SYNOPSIS

       systemd-userdbd.service

       /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 drop-in files in /etc/userdb/, /run/userdb/, /run/host/userdb/ and
       /usr/lib/userdb/.

       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.

SEE ALSO

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

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/