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man/systemd-sysusers.xml
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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/4.5/docbookx.dtd">
<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->

<refentry id="systemd-sysusers"
    xmlns:xi="http://www.w3.org/2001/XInclude">

  <refentryinfo>
    <title>systemd-sysusers</title>
    <productname>systemd</productname>
  </refentryinfo>

  <refmeta>
    <refentrytitle>systemd-sysusers</refentrytitle>
    <manvolnum>8</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>systemd-sysusers</refname>
    <refname>systemd-sysusers.service</refname>
    <refpurpose>Allocate system users and groups</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <cmdsynopsis>
      <command>systemd-sysusers</command>
      <arg choice="opt" rep="repeat">OPTIONS</arg>
      <arg choice="opt" rep="repeat"><replaceable>CONFIGFILE</replaceable></arg>
    </cmdsynopsis>

    <para><filename>systemd-sysusers.service</filename></para>
  </refsynopsisdiv>

  <refsect1>
    <title>Description</title>

    <para><command>systemd-sysusers</command> creates system users and groups, based on files in the format
    described in
    <citerefentry><refentrytitle>sysusers.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
    </para>

    <para>If invoked with no arguments, directives from the configuration files found in the directories
    specified by
    <citerefentry><refentrytitle>sysusers.d</refentrytitle><manvolnum>5</manvolnum></citerefentry> are
    executed. When invoked with positional arguments, if option
    <option>--replace=<replaceable>PATH</replaceable></option> is specified, arguments specified on the
    command line are used instead of the configuration file <replaceable>PATH</replaceable>. Otherwise, just
    the configuration specified by the command line arguments is executed. If the string <literal>-</literal>
    is specified instead of a filename, the configuration is read from standard input. If the argument is a
    file name (without any slashes), all configuration directories are searched for a matching file and the
    file found that has the highest priority is executed. If the argument is a path, that file is used
    directly without searching the configuration directories for any other matching file.</para>
  </refsect1>

  <refsect1>
    <title>Options</title>

    <para>The following options are understood:</para>

    <variablelist>
      <varlistentry>
        <term><option>--root=<replaceable>root</replaceable></option></term>
        <listitem><para>Takes a directory path as an argument. All
        paths will be prefixed with the given alternate
        <replaceable>root</replaceable> path, including config search
        paths. </para>

        <para>Note that this is not a sandboxing or security feature.
        <citerefentry><refentrytitle>sysusers.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>
        definitions are potentially not processed in a hermetic fashion to the specified root.</para>

        <xi:include href="version-info.xml" xpointer="v215"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--image=<replaceable>image</replaceable></option></term>

        <listitem><para>Takes a path to a disk image file or block device node. If specified all operations
        are applied to file system in the indicated disk image. This is similar to <option>--root=</option>
        but operates on file systems stored in disk images or block devices. The disk image should either
        contain just a file system or a set of file systems within a GPT partition table, following the
        <ulink url="https://uapi-group.org/specifications/specs/discoverable_partitions_specification">UAPI.2
        Discoverable Partitions Specification</ulink>. For further information on supported disk images, see
        <citerefentry><refentrytitle>systemd-nspawn</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
        switch of the same name.</para>

        <xi:include href="version-info.xml" xpointer="v247"/></listitem>
      </varlistentry>

      <xi:include href="standard-options.xml" xpointer="image-policy-open" />

      <varlistentry>
        <term><option>--replace=<replaceable>PATH</replaceable></option></term>
        <listitem><para>When this option is given, one or more positional arguments
        must be specified. All configuration files found in the directories listed in
        <citerefentry><refentrytitle>sysusers.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>
        will be read, and the configuration given on the command line will be
        handled instead of and with the same priority as the configuration file
        <replaceable>PATH</replaceable>.</para>

        <para>This option is intended to be used when package installation scripts
        are running and files belonging to that package are not yet available on
        disk, so their contents must be given on the command line, but the admin
        configuration might already exist and should be given higher priority.
        </para>

        <example>
          <title>RPM installation script for radvd</title>

          <programlisting>echo 'u radvd - "radvd daemon"' | \
          systemd-sysusers --replace=/usr/lib/sysusers.d/radvd.conf -</programlisting>

          <para>This will create the radvd user as if
          <filename>/usr/lib/sysusers.d/radvd.conf</filename> was already on disk.
          An admin might override the configuration specified on the command line by
          placing <filename>/etc/sysusers.d/radvd.conf</filename> or even
          <filename>/etc/sysusers.d/00-overrides.conf</filename>.</para>

          <para>Note that this is the expanded form, and when used in a package, this
          would be written using a macro with "radvd" and a file containing the
          configuration line as arguments.</para>
        </example>

          <xi:include href="version-info.xml" xpointer="v238"/>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-n</option></term>
        <term><option>--dry-run</option></term>
        <listitem><para>Process the configuration and figure out what entries would be created, but do not
        actually write anything. The short option <option>-n</option> was added in version 262.</para>

        <xi:include href="version-info.xml" xpointer="v250"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--inline</option></term>
        <listitem><para>Treat each positional argument as a separate configuration
        line instead of a file name.</para>

        <xi:include href="version-info.xml" xpointer="v238"/></listitem>
      </varlistentry>

      <xi:include href="standard-options.xml" xpointer="cat-config" />
      <xi:include href="standard-options.xml" xpointer="tldr" />
      <xi:include href="standard-options.xml" xpointer="no-pager" />
      <xi:include href="standard-options.xml" xpointer="help" />
      <xi:include href="standard-options.xml" xpointer="version" />
    </variablelist>
  </refsect1>

  <refsect1>
    <title>Credentials</title>

    <para><command>systemd-sysusers</command> supports the service credentials logic as implemented by
    <varname>ImportCredential=</varname>/<varname>LoadCredential=</varname>/<varname>SetCredential=</varname>
    (see <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry> for
    details). The following credentials are used when passed in:</para>

    <variablelist class='system-credentials'>
      <varlistentry>
        <term><varname>passwd.hashed-password.<replaceable>user</replaceable></varname></term>
        <listitem><para>A UNIX hashed password string to use for the specified user, when creating an entry
        for it. This is particularly useful for the <literal>root</literal> user as it allows provisioning
        the default root password to use via a unit file drop-in or from a container manager passing in this
        credential. Note that setting this credential has no effect if the specified user account already
        exists. This credential is hence primarily useful in first boot scenarios or systems that are fully
        stateless and come up with an empty <filename>/etc/</filename> on every boot.</para>

        <xi:include href="version-info.xml" xpointer="v249"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>passwd.plaintext-password.<replaceable>user</replaceable></varname></term>

        <listitem><para>Similar to <literal>passwd.hashed-password.<replaceable>user</replaceable></literal>
        but expect a literal, plaintext password, which is then automatically hashed before used for the user
        account. If both the hashed and the plaintext credential are specified for the same user the
        former takes precedence. It's generally recommended to specify the hashed version; however in test
        environments with weaker requirements on security it might be easier to pass passwords in plaintext
        instead.</para>

        <xi:include href="version-info.xml" xpointer="v249"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>passwd.shell.<replaceable>user</replaceable></varname></term>

        <listitem><para>Specifies the shell binary to use for the specified account when creating it.</para>

        <xi:include href="version-info.xml" xpointer="v249"/></listitem>
      </varlistentry>

      <varlistentry>
        <term><varname>sysusers.extra</varname></term>

        <listitem><para>The contents of this credential may contain additional lines to operate on. The
        credential contents should follow the same format as any other <filename>sysusers.d/</filename>
        drop-in. If this credential is passed it is processed after all of the drop-in files read from the
        file system.</para>

        <xi:include href="version-info.xml" xpointer="v252"/></listitem>
      </varlistentry>
    </variablelist>

    <para>Note that by default the <filename>systemd-sysusers.service</filename> unit file is set up to
    inherit the <literal>passwd.hashed-password.root</literal>,
    <literal>passwd.plaintext-password.root</literal>, <literal>passwd.shell.root</literal> and
    <literal>sysusers.extra</literal> credentials from the service manager. Thus, when invoking a container
    with an unpopulated <filename>/etc/</filename> for the first time it is possible to configure the root
    user's password to be <literal>systemd</literal> like this:</para>

    <para><programlisting># systemd-nspawn --image=… --set-credential=passwd.hashed-password.root:'$y$j9T$yAuRJu1o5HioZAGDYPU5d.$F64ni6J2y2nNQve90M/p0ZP0ECP/qqzipNyaY9fjGpC' …</programlisting></para>

    <para>Note again that the data specified in this credential is consulted only when creating an account
    for the first time, it may not be used for changing the password or shell of an account that already
    exists.</para>

    <para>Use <citerefentry project='man-pages'><refentrytitle>mkpasswd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
    for generating UNIX password hashes from the command line.</para>
  </refsect1>

  <refsect1>
    <title>Exit status</title>

    <para>On success, 0 is returned, a non-zero failure code
    otherwise.</para>
  </refsect1>

  <refsect1>
    <title>See Also</title>
    <para><simplelist type="inline">
      <member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
      <member><citerefentry><refentrytitle>sysusers.d</refentrytitle><manvolnum>5</manvolnum></citerefentry></member>
      <member><ulink url="https://systemd.io/UIDS-GIDS">Users, Groups, UIDs and GIDs on systemd systems</ulink></member>
      <member><citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry></member>
      <member><citerefentry project='man-pages'><refentrytitle>mkpasswd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
    </simplelist></para>
  </refsect1>

</refentry>