man/nss-systemd.xml

   1 <?xml version='1.0'?> <!--*-nxml-*-->
   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   3   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
   4 <!-- SPDX-License-Identifier: LGPL-2.1+ -->
   5
   6 <refentry id="nss-systemd" conditional='ENABLE_NSS_SYSTEMD'>
   7
   8   <refentryinfo>
   9     <title>nss-systemd</title>
  10     <productname>systemd</productname>
  11   </refentryinfo>
  12
  13   <refmeta>
  14     <refentrytitle>nss-systemd</refentrytitle>
  15     <manvolnum>8</manvolnum>
  16   </refmeta>
  17
  18   <refnamediv>
  19     <refname>nss-systemd</refname>
  20     <refname>libnss_systemd.so.2</refname>
  21     <refpurpose>Provide UNIX user and group name resolution for dynamic users and groups.</refpurpose>
  22   </refnamediv>
  23
  24   <refsynopsisdiv>
  25     <para><filename>libnss_systemd.so.2</filename></para>
  26   </refsynopsisdiv>
  27
  28   <refsect1>
  29     <title>Description</title>
  30
  31     <para><command>nss-systemd</command> is a plug-in module for the GNU Name Service Switch (NSS) functionality of the
  32     GNU C Library (<command>glibc</command>), providing UNIX user and group name resolution for dynamic users and
  33     groups allocated through the <varname>DynamicUser=</varname> option in systemd unit files. See
  34     <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry> for details on
  35     this option.</para>
  36
  37     <para>This module also ensures that the root and nobody users and groups (i.e. the users/groups with the UIDs/GIDs
  38     0 and 65534) remain resolvable at all times, even if they aren't listed in <filename>/etc/passwd</filename> or
  39     <filename>/etc/group</filename>, or if these files are missing.</para>
  40
  41     <para>To activate the NSS module, add <literal>systemd</literal> to the lines starting with
  42     <literal>passwd:</literal> and <literal>group:</literal> in <filename>/etc/nsswitch.conf</filename>.</para>
  43
  44     <para>It is recommended to place <literal>systemd</literal> after the <literal>files</literal> or
  45     <literal>compat</literal> entry of the <filename>/etc/nsswitch.conf</filename> lines so that
  46     <filename>/etc/passwd</filename> and <filename>/etc/group</filename> based mappings take precedence.</para>
  47   </refsect1>
  48
  49   <refsect1>
  50     <title>Example</title>
  51
  52     <para>Here is an example <filename>/etc/nsswitch.conf</filename> file that enables
  53     <command>nss-systemd</command> correctly:</para>
  54
  55     <!-- synchronize with other nss-* man pages and factory/etc/nsswitch.conf -->
  56     <programlisting>passwd:         compat mymachines <command>systemd</command>
  57 group:          compat mymachines <command>systemd</command>
  58 shadow:         compat
  59
  60 hosts:          files mymachines resolve [!UNAVAIL=return] dns myhostname
  61 networks:       files
  62
  63 protocols:      db files
  64 services:       db files
  65 ethers:         db files
  66 rpc:            db files
  67
  68 netgroup:       nis</programlisting>
  69
  70   </refsect1>
  71
  72   <refsect1>
  73     <title>See Also</title>
  74     <para>
  75       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
  76       <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
  77       <citerefentry><refentrytitle>nss-resolve</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
  78       <citerefentry><refentrytitle>nss-myhostname</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
  79       <citerefentry><refentrytitle>nss-mymachines</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
  80       <citerefentry project='man-pages'><refentrytitle>nsswitch.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
  81       <citerefentry project='man-pages'><refentrytitle>getent</refentrytitle><manvolnum>1</manvolnum></citerefentry>
  82     </para>
  83   </refsect1>
  84
  85 </refentry>