systemd/man/userdbctl.xml

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<refentry id="userdbctl" conditional='ENABLE_USERDB'
    xmlns:xi="http://www.w3.org/2001/XInclude">

  <refentryinfo>
    <title>userdbctl</title>
    <productname>systemd</productname>
  </refentryinfo>

  <refmeta>
    <refentrytitle>userdbctl</refentrytitle>
    <manvolnum>1</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>userdbctl</refname>
    <refpurpose>Inspect users, groups and group memberships</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <cmdsynopsis>
      <command>userdbctl</command>
      <arg choice="opt" rep="repeat">OPTIONS</arg>
      <arg choice="req">COMMAND</arg>
      <arg choice="opt" rep="repeat">NAME</arg>
    </cmdsynopsis>
  </refsynopsisdiv>

  <refsect1>
    <title>Description</title>

    <para><command>userdbctl</command> may be used to inspect user and groups (as well as group memberships)
    of the system. This client utility inquires user/group information provided by various system services,
    both operating on JSON user/group records (as defined by the <ulink
    url="https://systemd.io/USER_RECORD">JSON User Records</ulink> and <ulink
    url="https://systemd.io/GROUP_RECORD">JSON Group Records</ulink> definitions), and classic UNIX NSS/glibc
    user and group records. This tool is primarily a client to the <ulink
    url="https://systemd.io/USER_GROUP_API">User/Group Record Lookup API via Varlink</ulink>, and may also
    pick up drop-in JSON user and group records from <filename>/etc/userdb/</filename>,
    <filename>/run/userdb/</filename>, <filename>/run/host/userdb/</filename>,
    <filename>/use/lib/userdb/</filename>.</para>
  </refsect1>

  <refsect1>
    <title>Options</title>

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

    <variablelist>

      <varlistentry>
        <term><option>--output=</option><replaceable>MODE</replaceable></term>

        <listitem><para>Choose the output mode, takes one of <literal>classic</literal>,
        <literal>friendly</literal>, <literal>table</literal>, <literal>json</literal>. If
        <literal>classic</literal>, an output very close to the format of <filename>/etc/passwd</filename> or
        <filename>/etc/group</filename> is generated. If <literal>friendly</literal> a more comprehensive and
        user friendly, human readable output is generated; if <literal>table</literal> a minimal, tabular
        output is generated; if <literal>json</literal> a JSON formatted output is generated. Defaults to
        <literal>friendly</literal> if a user/group is specified on the command line,
        <literal>table</literal> otherwise.</para>

        <para>Note that most output formats do not show all available information. In particular,
        <literal>classic</literal> and <literal>table</literal> show only the most important fields. Various
        modes also do not show password hashes. Use <literal>json</literal> to view all fields, including
        any authentication fields.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--service=</option><replaceable>SERVICE</replaceable><optional>:<replaceable>SERVICE…</replaceable></optional></term>
        <term><option>-s</option> <replaceable>SERVICE</replaceable>:<replaceable>SERVICE…</replaceable></term>

        <listitem><para>Controls which services to query for users/groups. Takes a list of one or more
        service names, separated by <literal>:</literal>. See below for a list of well-known service
        names. If not specified all available services are queried at once.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--with-nss=</option><replaceable>BOOL</replaceable></term>

        <listitem><para>Controls whether to include classic glibc/NSS user/group lookups in the output. If
        <option>--with-nss=no</option> is used any attempts to resolve or enumerate users/groups provided
        only via glibc NSS is suppressed. If <option>--with-nss=yes</option> is specified such users/groups
        are included in the output (which is the default).</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--with-varlink=</option><replaceable>BOOL</replaceable></term>

        <listitem><para>Controls whether to include Varlink user/group lookups in the output, i.e. those done
        via the <ulink url="https://systemd.io/USER_GROUP_API">User/Group Record Lookup API via
        Varlink</ulink>. If <option>--with-varlink=no</option> is used any attempts to resolve or enumerate
        users/groups provided only via Varlink are suppressed. If <option>--with-varlink=yes</option> is
        specified such users/groups are included in the output (which is the default).</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--with-dropin=</option><replaceable>BOOL</replaceable></term>

        <listitem><para>Controls whether to include user/group lookups in the output that are defined using
        drop-in files in <filename>/etc/userdb/</filename>, <filename>/run/userdb/</filename>,
        <filename>/run/host/userdb/</filename>, <filename>/use/lib/userdb/</filename>. If
        <option>--with-dropin=no</option> is used these records are suppressed. If
        <option>--with-dropin=yes</option> is specified such users/groups are included in the output (which
        is the default).</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--synthesize=</option><replaceable>BOOL</replaceable></term>

        <listitem><para>Controls whether to synthesize records for the root and nobody users/groups if they
        aren't defined otherwise. By default (or <literal>yes</literal>) such records are implicitly
        synthesized if otherwise missing since they have special significance to the OS. When
        <literal>no</literal> this synthesizing is turned off.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-N</option></term>

        <listitem><para>This option is short for <option>--with-nss=no</option>
        <option>--synthesize=no</option>. Use this option to show only records that are natively defined as
        JSON user or group records, with all NSS/glibc compatibility and all implicit synthesis turned
        off.</para></listitem>
      </varlistentry>

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

  <refsect1>
    <title>Commands</title>

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

    <variablelist>

      <varlistentry>
        <term><command>user</command> <optional><replaceable>USER</replaceable>…</optional></term>

        <listitem><para>List all known users records or show details of one or more specified user
        records. Use <option>--output=</option> to tweak output mode.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><command>group</command> <optional><replaceable>GROUP</replaceable>…</optional></term>

        <listitem><para>List all known group records or show details of one or more specified group
        records. Use <option>--output=</option> to tweak output mode.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><command>users-in-group</command> <optional><replaceable>GROUP</replaceable>…</optional></term>

        <listitem><para>List users that are members of the specified groups. If no groups are specified list
        all user/group memberships defined. Use <option>--output=</option> to tweak output
        mode.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><command>groups-of-user</command> <optional><replaceable>USER</replaceable>…</optional></term>

        <listitem><para>List groups that the specified users are members of. If no users are specified list
        all user/group memberships defined (in this case <command>groups-of-user</command> and
        <command>users-in-group</command> are equivalent). Use <option>--output=</option> to tweak output
        mode.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><command>services</command></term>

        <listitem><para>List all services currently providing user/group definitions to the system. See below
        for a list of well-known services providing user information.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><command>ssh-authorized-keys</command></term>

        <listitem><para>This operation is not a public, user-facing interface. It is used to allow the SSH daemon to pick
        up authorized keys from user records, see below.</para></listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>Well-Known Services</title>

    <para>The <command>userdbctl services</command> command will list all currently running services that
    provide user or group definitions to the system. The following well-known services are shown among
    this list:</para>

    <variablelist>
      <varlistentry>
        <term><constant>io.systemd.DynamicUser</constant></term>

        <listitem><para>This service is provided by the system service manager itself (i.e. PID 1) and
        makes all users (and their groups) synthesized through the <varname>DynamicUser=</varname> setting in
        service unit files available to the system (see
        <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry> for
        details about this setting).</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><constant>io.systemd.Home</constant></term>

        <listitem><para>This service is provided by
        <citerefentry><refentrytitle>systemd-homed.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
        and makes all users (and their groups) belonging to home directories managed by that service
        available to the system.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><constant>io.systemd.Machine</constant></term>

        <listitem><para>This service is provided by
        <citerefentry><refentrytitle>systemd-machined.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
        and synthesizes records for all users/groups used by a container that employs user
        namespacing.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><constant>io.systemd.Multiplexer</constant></term>

        <listitem><para>This service is provided by
        <citerefentry><refentrytitle>systemd-userdbd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
        and multiplexes user/group look-ups to all other running lookup services. This is the primary entry point
        for user/group record clients, as it simplifies client side implementation substantially since they
        can ask a single service for lookups instead of asking all running services in parallel.
        <command>userdbctl</command> uses this service preferably, too, unless <option>--with-nss=</option>
        or <option>--service=</option> are used, in which case finer control over the services to talk to is
        required.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><constant>io.systemd.NameServiceSwitch</constant></term>

        <listitem><para>This service is (also) provided by
        <citerefentry><refentrytitle>systemd-userdbd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
        and converts classic NSS/glibc user and group records to JSON user/group records, providing full
        backwards compatibility. Use <option>--with-nss=no</option> to disable this compatibility, see
        above. Note that compatibility is actually provided in both directions:
        <citerefentry><refentrytitle>nss-systemd</refentrytitle><manvolnum>8</manvolnum></citerefentry> will
        automatically synthesize classic NSS/glibc user/group records from all JSON user/group records
        provided to the system, thus using both APIs is mostly equivalent and provides access to the same
        data, however the NSS/glibc APIs necessarily expose a more reduced set of fields
        only.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><constant>io.systemd.DropIn</constant></term>

        <listitem><para>This service is (also) provided by
        <citerefentry><refentrytitle>systemd-userdbd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
        and picks up JSON user/group records from <filename>/etc/userdb/</filename>,
        <filename>/run/userdb/</filename>, <filename>/run/host/userdb/</filename>,
        <filename>/use/lib/userdb/</filename>.</para></listitem>
      </varlistentry>

    </variablelist>

    <para>Note that <command>userdbctl</command> has internal support for NSS-based lookups too. This means
    that if neither <constant>io.systemd.Multiplexer</constant> nor
    <constant>io.systemd.NameServiceSwitch</constant> are running look-ups into the basic user/group
    databases will still work.</para>
  </refsect1>

  <refsect1>
    <title>Integration with SSH</title>

    <para>The <command>userdbctl</command> tool may be used to make the list of SSH authorized keys possibly
    contained in a user record available to the SSH daemon for authentication. For that configure the
    following in <citerefentry
    project='die-net'><refentrytitle>sshd_config</refentrytitle><manvolnum>5</manvolnum></citerefentry>:</para>

    <programlisting>…
AuthorizedKeysCommand /usr/bin/userdbctl ssh-authorized-keys %u
AuthorizedKeysCommandUser root
…</programlisting>
  </refsect1>

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

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

  <xi:include href="common-variables.xml" />

  <refsect1>
    <title>See Also</title>
    <para>
      <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>systemd-userdbd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>systemd-homed.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>nss-systemd</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
      <citerefentry project='man-pages'><refentrytitle>getent</refentrytitle><manvolnum>1</manvolnum></citerefentry>
    </para>
  </refsect1>

</refentry>