mirror of
https://github.com/systemd/systemd
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233 lines
9.7 KiB
XML
233 lines
9.7 KiB
XML
<?xml version='1.0'?>
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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"http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">
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<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
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<refentry id="uid0"
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xmlns:xi="http://www.w3.org/2001/XInclude">
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<refentryinfo>
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<title>uid0</title>
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<productname>systemd</productname>
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</refentryinfo>
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<refmeta>
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<refentrytitle>uid0</refentrytitle>
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<manvolnum>1</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>uid0</refname>
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<refpurpose>Elevate privileges</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<cmdsynopsis>
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<command>uid0</command>
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<arg choice="opt" rep="repeat">OPTIONS</arg>
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<arg choice="opt" rep="repeat">COMMAND</arg>
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</cmdsynopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para><command>uid0</command> may be used to temporarily and interactively acquire elevated or different
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privileges. It serves a similar purpose as <citerefentry
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project='man-pages'><refentrytitle>sudo</refentrytitle><manvolnum>8</manvolnum></citerefentry>, but
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operates differently in a couple of key areas:</para>
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<itemizedlist>
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<listitem><para>No execution or security context credentials are inherited from the caller into the
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invoked commands, as they are invoked from a fresh, isolated service forked off the service
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manager.</para></listitem>
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<listitem><para>Authentication takes place via <ulink
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url="https://www.freedesktop.org/wiki/Software/polkit">polkit</ulink>, thus isolating the
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authentication prompt from the terminal (if possible).</para></listitem>
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<listitem><para>An independent pseudo-tty is allocated for the invoked command, detaching its lifecycle and
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isolating it for security.</para></listitem>
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<listitem><para>No SetUID/SetGID file access bit functionality is used for the implementation.</para></listitem>
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</itemizedlist>
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<para>Altogether this should provide a safer and more robust alternative to the <command>sudo</command>
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mechanism, in particular in OS environments where SetUID/SetGID support is not available (for example by
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setting the <varname>NoNewPrivileges=</varname> variable in
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<citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>).</para>
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<para>Any session invoked via <command>uid0</command> will run through the
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<literal>systemd-uid0</literal> PAM stack.</para>
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<para>Note that <command>uid0</command> is implemented as an alternative multi-call invocation of
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<citerefentry><refentrytitle>systemd-run</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
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</refsect1>
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<refsect1>
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<title>Options</title>
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<para>The following options are understood:</para>
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<variablelist>
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<varlistentry>
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<term><option>--no-ask-password</option></term>
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<listitem><para>Do not query the user for authentication for privileged operations.</para>
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<xi:include href="version-info.xml" xpointer="v256"/></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--unit=</option></term>
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<listitem><para>Use this unit name instead of an automatically generated one.</para>
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<xi:include href="version-info.xml" xpointer="v256"/></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--property=</option></term>
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<listitem><para>Sets a property on the service unit that is created. This option takes an assignment
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in the same format as
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<citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
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<command>set-property</command> command.</para>
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<xi:include href="version-info.xml" xpointer="v256"/>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--description=</option></term>
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<listitem><para>Provide a description for the service unit that is invoked. If not specified,
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the command itself will be used as a description. See <varname>Description=</varname> in
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<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
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</para>
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<xi:include href="version-info.xml" xpointer="v256"/></listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--slice=</option></term>
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<listitem><para>Make the new <filename>.service</filename> unit part of the specified slice, instead
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of <filename>user.slice</filename>.</para>
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<xi:include href="version-info.xml" xpointer="v256"/>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--slice-inherit</option></term>
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<listitem><para>Make the new <filename>.service</filename> unit part of the slice the
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<command>uid0</command> itself has been invoked in. This option may be combined with
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<option>--slice=</option>, in which case the slice specified via <option>--slice=</option> is placed
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within the slice the <command>uid0</command> command is invoked in.</para>
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<para>Example: consider <command>uid0</command> being invoked in the slice
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<filename>foo.slice</filename>, and the <option>--slice=</option> argument is
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<filename>bar</filename>. The unit will then be placed under
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<filename>foo-bar.slice</filename>.</para>
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<xi:include href="version-info.xml" xpointer="v256"/>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--user=</option></term>
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<term><option>-u</option></term>
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<term><option>--group=</option></term>
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<term><option>-g</option></term>
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<listitem><para>Switches to the specified user/group instead of root.</para>
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<xi:include href="version-info.xml" xpointer="v256"/>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--nice=</option></term>
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<listitem><para>Runs the invoked session with the specified nice level.</para>
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<xi:include href="version-info.xml" xpointer="v256"/>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--chdir=</option></term>
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<term><option>-D</option></term>
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<listitem><para>Runs the invoked session with the specified working directory. If not specified
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defaults to the client's current working directory if switching to the root user, or the target
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user's home directory otherwise.</para>
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<xi:include href="version-info.xml" xpointer="v256"/>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--setenv=<replaceable>NAME</replaceable>[=<replaceable>VALUE</replaceable>]</option></term>
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<listitem><para>Runs the invoked session with the specified environment variable set. This parameter
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may be used more than once to set multiple variables. When <literal>=</literal> and
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<replaceable>VALUE</replaceable> are omitted, the value of the variable with the same name in the
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invoking environment will be used.</para>
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<xi:include href="version-info.xml" xpointer="v256"/>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>--background=<replaceable>COLOR</replaceable></option></term>
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<listitem><para>Change the terminal background color to the specified ANSI color as long as the
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session lasts. If not specified, the background will be tinted in a reddish tone when operating as
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root, and in a yellowish tone when operating under another UID, as reminder of the changed
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privileges. The color specified should be an ANSI X3.64 SGR background color, i.e. strings such as
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<literal>40</literal>, <literal>41</literal>, …, <literal>47</literal>, <literal>48;2;…</literal>,
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<literal>48;5;…</literal>. See <ulink
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url="https://en.wikipedia.org/wiki/ANSI_escape_code#SGR_(Select_Graphic_Rendition)_parameters">ANSI
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Escape Code (Wikipedia)</ulink> for details. Set to an empty string to disable.</para>
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<para>Example: <literal>--background=44</literal> for a blue background.</para>
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<xi:include href="version-info.xml" xpointer="v256"/>
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</listitem>
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</varlistentry>
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<xi:include href="user-system-options.xml" xpointer="machine" />
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<xi:include href="standard-options.xml" xpointer="help" />
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<xi:include href="standard-options.xml" xpointer="version" />
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</variablelist>
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<para>All command line arguments after the first non-option argument become part of the command line of
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the launched process. If no command line is specified an interactive shell is invoked. The shell to
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invoke may be controlled via <option>--setenv=SHELL=…</option> and currently defaults to the
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<emphasis>originating user's</emphasis> shell (i.e. not the target user's!) if operating locally, or
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<filename>/bin/sh</filename> when operating with <option>--machine=</option>.</para>
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</refsect1>
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<refsect1>
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<title>Exit status</title>
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<para>On success, 0 is returned. If <command>uid0</command> failed to start the session or the specified command fails, a
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non-zero return value will be returned.</para>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<para><simplelist type="inline">
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<member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
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<member><citerefentry><refentrytitle>systemd-run</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
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<member><citerefentry project='man-pages'><refentrytitle>sudo</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
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<member><citerefentry><refentrytitle>machinectl</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
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</simplelist></para>
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</refsect1>
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</refentry>
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