man/nss-systemd.xml

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   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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   5 <!--
   6   SPDX-License-Identifier: LGPL-2.1+
   7
   8   This file is part of systemd.
   9
  10   Copyright 2016 Lennart Poettering
  11 -->
  12
  13 <refentry id="nss-systemd" conditional='ENABLE_NSS_SYSTEMD'>
  14
  15   <refentryinfo>
  16     <title>nss-systemd</title>
  17     <productname>systemd</productname>
  18
  19     <authorgroup>
  20       <author>
  21         <contrib>Developer</contrib>
  22         <firstname>Lennart</firstname>
  23         <surname>Poettering</surname>
  24         <email>lennart@poettering.net</email>
  25       </author>
  26     </authorgroup>
  27   </refentryinfo>
  28
  29   <refmeta>
  30     <refentrytitle>nss-systemd</refentrytitle>
  31     <manvolnum>8</manvolnum>
  32   </refmeta>
  33
  34   <refnamediv>
  35     <refname>nss-systemd</refname>
  36     <refname>libnss_systemd.so.2</refname>
  37     <refpurpose>Provide UNIX user and group name resolution for dynamic users and groups.</refpurpose>
  38   </refnamediv>
  39
  40   <refsynopsisdiv>
  41     <para><filename>libnss_systemd.so.2</filename></para>
  42   </refsynopsisdiv>
  43
  44   <refsect1>
  45     <title>Description</title>
  46
  47     <para><command>nss-systemd</command> is a plug-in module for the GNU Name Service Switch (NSS) functionality of the
  48     GNU C Library (<command>glibc</command>), providing UNIX user and group name resolution for dynamic users and
  49     groups allocated through the <varname>DynamicUser=</varname> option in systemd unit files. See
  50     <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry> for details on
  51     this option.</para>
  52
  53     <para>This module also ensures that the root and nobody users and groups (i.e. the users/groups with the UIDs/GIDs
  54     0 and 65534) remain resolvable at all times, even if they aren't listed in <filename>/etc/passwd</filename> or
  55     <filename>/etc/group</filename>, or if these files are missing.</para>
  56
  57     <para>To activate the NSS module, add <literal>systemd</literal> to the lines starting with
  58     <literal>passwd:</literal> and <literal>group:</literal> in <filename>/etc/nsswitch.conf</filename>.</para>
  59
  60     <para>It is recommended to place <literal>systemd</literal> after the <literal>files</literal> or
  61     <literal>compat</literal> entry of the <filename>/etc/nsswitch.conf</filename> lines so that
  62     <filename>/etc/passwd</filename> and <filename>/etc/group</filename> based mappings take precedence.</para>
  63   </refsect1>
  64
  65   <refsect1>
  66     <title>Example</title>
  67
  68     <para>Here is an example <filename>/etc/nsswitch.conf</filename> file that enables
  69     <command>nss-systemd</command> correctly:</para>
  70
  71     <programlisting>passwd:         compat mymachines <command>systemd</command>
  72 group:          compat mymachines <command>systemd</command>
  73 shadow:         compat
  74
  75 hosts:          files mymachines resolve [!UNAVAIL=return] dns myhostname
  76 networks:       files
  77
  78 protocols:      db files
  79 services:       db files
  80 ethers:         db files
  81 rpc:            db files
  82
  83 netgroup:       nis</programlisting>
  84
  85   </refsect1>
  86
  87   <refsect1>
  88     <title>See Also</title>
  89     <para>
  90       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
  91       <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
  92       <citerefentry><refentrytitle>nss-resolve</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
  93       <citerefentry><refentrytitle>nss-myhostname</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
  94       <citerefentry><refentrytitle>nss-mymachines</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
  95       <citerefentry project='man-pages'><refentrytitle>nsswitch.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
  96       <citerefentry project='man-pages'><refentrytitle>getent</refentrytitle><manvolnum>1</manvolnum></citerefentry>
  97     </para>
  98   </refsect1>
  99
 100 </refentry>