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<?xml version='1.0'?> <!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!-- SPDX-License-Identifier: LGPL-2.1+ -->
<refentry id="nss-systemd" conditional='ENABLE_NSS_SYSTEMD'>
<refentryinfo>
<title>nss-systemd</title>
<productname>systemd</productname>
</refentryinfo>
<refmeta>
<refentrytitle>nss-systemd</refentrytitle>
<manvolnum>8</manvolnum>
</refmeta>
<refnamediv>
<refname>nss-systemd</refname>
<refname>libnss_systemd.so.2</refname>
<refpurpose>Provide UNIX user and group name resolution for user/group lookup via Varlink</refpurpose>
</refnamediv>
<refsynopsisdiv>
<para><filename>libnss_systemd.so.2</filename></para>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><command>nss-systemd</command> is a plug-in module for the GNU Name Service Switch (NSS)
functionality of the GNU C Library (<command>glibc</command>), providing UNIX user and group name
resolution for services implementing the <ulink url="https://systemd.io/USER_GROUP_API">User/Group Record
Lookup API via Varlink</ulink>, such as the system and service manager
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry> (for its
<varname>DynamicUser=</varname> feature, see
<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry> for
details) or
<citerefentry><refentrytitle>systemd-homed.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
<para>This module also ensures that the root and nobody users and groups (i.e. the users/groups with the UIDs/GIDs
0 and 65534) remain resolvable at all times, even if they aren't listed in <filename>/etc/passwd</filename> or
<filename>/etc/group</filename>, or if these files are missing.</para>
<para>This module preferably utilizes
<citerefentry><refentrytitle>systemd-userdbd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
for resolving users and groups, but also works without the service running.</para>
<para>To activate the NSS module, add <literal>systemd</literal> to the lines starting with
<literal>passwd:</literal> and <literal>group:</literal> in <filename>/etc/nsswitch.conf</filename>.</para>
<para>It is recommended to place <literal>systemd</literal> after the <literal>files</literal> or
<literal>compat</literal> entry of the <filename>/etc/nsswitch.conf</filename> lines so that
<filename>/etc/passwd</filename> and <filename>/etc/group</filename> based mappings take precedence.</para>
</refsect1>
<refsect1>
<title>Example</title>
<para>Here is an example <filename>/etc/nsswitch.conf</filename> file that enables
<command>nss-systemd</command> correctly:</para>
<!-- synchronize with other nss-* man pages and factory/etc/nsswitch.conf -->
<programlisting>passwd: compat mymachines <command>systemd</command>
group: compat [SUCCESS=merge] mymachines [SUCCESS=merge] <command>systemd</command>
shadow: compat
hosts: mymachines resolve [!UNAVAIL=return] myhostname files dns
networks: files
protocols: db files
services: db files
ethers: db files
rpc: db files
netgroup: nis</programlisting>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>nss-resolve</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry><refentrytitle>nss-myhostname</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry><refentrytitle>nss-mymachines</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry project='man-pages'><refentrytitle>nsswitch.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry project='man-pages'><refentrytitle>getent</refentrytitle><manvolnum>1</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>
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