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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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SYSTEMD-U....SERVICE(8) systemd-userdbd.service SYSTEMD-U....SERVICE(8)
systemd-userdbd.service, systemd-userdbd - JSON User/Group Record
Query Multiplexer/NSS Compatibility
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" extension.
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/
This page is part of the systemd (systemd system and service
manager) project. Information about the project can be found at
⟨http://www.freedesktop.org/wiki/Software/systemd⟩. If you have a
bug report for this manual page, see
⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩.
This page was obtained from the project's upstream Git repository
⟨https://github.com/systemd/systemd.git⟩ on 2025-08-11. (At that
time, the date of the most recent commit that was found in the
repository was 2025-08-11.) If you discover any rendering
problems in this HTML version of the page, or you believe there is
a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
[email protected]
systemd 258~rc2 SYSTEMD-U....SERVICE(8)
Pages that refer to this page: userdbctl(1), systemd.directives(7), systemd.index(7), nss-systemd(8)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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