mirror of
https://github.com/systemd/systemd.git
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700 lines
38 KiB
XML
700 lines
38 KiB
XML
<?xml version='1.0'?> <!--*-nxml-*-->
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<!--
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This file is part of systemd.
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Copyright 2010 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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-->
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<refentry id="systemd.special">
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<refentryinfo>
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<title>systemd.special</title>
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<productname>systemd</productname>
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<authorgroup>
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<author>
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<contrib>Developer</contrib>
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<firstname>Lennart</firstname>
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<surname>Poettering</surname>
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<email>lennart@poettering.net</email>
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</author>
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</authorgroup>
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</refentryinfo>
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<refmeta>
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<refentrytitle>systemd.special</refentrytitle>
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<manvolnum>7</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>systemd.special</refname>
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<refpurpose>special systemd units</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<para><filename>basic.target</filename>,
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<filename>ctrl-alt-del.target</filename>,
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<filename>dbus.service</filename>,
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<filename>default.target</filename>,
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<filename>display-manager.service</filename>,
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<filename>emergency.target</filename>,
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<filename>exit.service</filename>,
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<filename>graphical.target</filename>,
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<filename>halt.target</filename>,
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<filename>kbrequest.target</filename>,
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<filename>local-fs.target</filename>,
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<filename>mail-transfer-agent.target</filename>,
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<filename>multi-user.target</filename>,
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<filename>network.target</filename>,
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<filename>nss-lookup.target</filename>,
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<filename>poweroff.target</filename>,
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<filename>reboot.target</filename>,
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<filename>remote-fs.target</filename>,
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<filename>rescue.target</filename>,
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<filename>rpcbind.target</filename>,
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<filename>time-sync.target</filename>,
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<filename>runlevel2.target</filename>,
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<filename>runlevel3.target</filename>,
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<filename>runlevel4.target</filename>,
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<filename>runlevel5.target</filename>,
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<filename>shutdown.target</filename>,
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<filename>sigpwr.target</filename>,
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<filename>sockets.target</filename>,
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<filename>swap.target</filename>,
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<filename>sysinit.target</filename>,
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<filename>syslog.target</filename>,
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<filename>systemd-initctl.service</filename>,
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<filename>systemd-initctl.socket</filename>,
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<filename>systemd-logger.service</filename>,
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<filename>systemd-logger.socket</filename>,
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<filename>umount.target</filename></para>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para>A few units are treated specially by
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systemd. They have special internal semantics and
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cannot be renamed.</para>
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</refsect1>
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<refsect1>
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<title>Special System Units</title>
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<variablelist>
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<varlistentry>
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<term><filename>basic.target</filename></term>
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<listitem>
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<para>A special target unit
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covering early boot-up.</para>
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<para>systemd automatically
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adds dependencies of the types
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Requires and After for this
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target unit to all SysV
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service units configured for
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runlevel 1 to 5.</para>
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<para>Usually this should pull-in
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all sockets, mount points,
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swap devices and other basic
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initialization necessary for
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the general purpose
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daemons. Most normal daemons
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should have dependencies of
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type After and Requires on
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this unit.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><filename>ctrl-alt-del.target</filename></term>
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<listitem>
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<para>systemd starts this
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target whenever
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Control+Alt+Del is pressed on
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the console. Usually this
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should be aliased (symlinked)
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to
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<filename>reboot.target</filename>.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><filename>dbus.service</filename></term>
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<listitem>
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<para>A special unit for the
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D-Bus system bus. As soon as
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this service is fully started
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up systemd will connect to it
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and register its
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service.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><filename>default.target</filename></term>
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<listitem>
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<para>The default unit systemd
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starts at bootup. Usually this
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should be aliased (symlinked)
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to
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<filename>multi-user.target</filename>
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or
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<filename>graphical.target</filename>.</para>
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<para>The default unit systemd
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starts at bootup can be
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overridden with the
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<varname>systemd.unit=</varname>
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kernel command line option.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><filename>display-manager.service</filename></term>
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<listitem>
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<para>The display manager
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service. Usually this should
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be aliased (symlinked) to
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<filename>xdm.service</filename>
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or a similar display manager
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service.</para>
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<para>systemd automatically
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adds dependencies of type
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After for this target unit to
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all SysV init script service
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units with a LSB header
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referring to the
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<literal>$x-display-manager</literal>
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facility, for compatibility
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with Debian.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><filename>emergency.target</filename></term>
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<listitem>
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<para>A special target unit
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that starts an emergency
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shell on the main
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console. This unit is supposed
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to be used with the kernel
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command line option
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<varname>systemd.unit=</varname>
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and has otherwise little use.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><filename>graphical.target</filename></term>
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<listitem>
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<para>A special target unit
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for setting up a graphical
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login screen. This pulls in
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<filename>multi-user.target</filename>.</para>
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<para>Units that are needed
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for graphical login shall add
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Wants dependencies for their
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unit to this unit (or
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<filename>multi-user.target</filename>)
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during installation.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><filename>halt.target</filename></term>
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<listitem>
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<para>A special target unit
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for shutting down and halting the system.</para>
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<para>Applications wanting to
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halt the system should start
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this unit.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><filename>kbrequest.target</filename></term>
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<listitem>
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<para>systemd starts this
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target whenever Alt+ArrowUp is
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pressed on the console. This
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is a good candidate to be
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aliased (symlinked) to
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<filename>rescue.target</filename>.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><filename>local-fs.target</filename></term>
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<listitem>
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<para>systemd automatically
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adds dependencies of type
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After to all mount units that
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refer to local mount points
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for this target unit. In
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addition, systemd adds
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dependencies of type Wants to
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this target unit for those
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mounts listed in
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<filename>/etc/fstab</filename>
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that have the
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<option>auto</option> and
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<option>comment=systemd.mount</option>
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mount options set.</para>
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<para>systemd automatically
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adds dependencies of type
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After for this target unit to
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all SysV init script service
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units with an LSB header
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referring to the
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<literal>$local_fs</literal>
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facility.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><filename>mail-transfer-agent.target</filename></term>
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<listitem>
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<para>The mail transfer agent
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(MTA) service. Usually this
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should pull-in all units
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necessary for
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sending/receiving mails on the
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local host.</para>
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<para>systemd automatically
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adds dependencies of type
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After for this target unit to
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all SysV init script service
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units with an LSB header
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referring to the
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<literal>$mail-transfer-agent</literal>
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or
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<literal>$mail-transport-agent</literal>
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facilities, for compatibility
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with Debian.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><filename>multi-user.target</filename></term>
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<listitem>
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<para>A special target unit
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for setting up a multi-user
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system (non-graphical). This
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is pulled in by
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<filename>graphical.target</filename>.</para>
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<para>Units that are needed
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for a multi-user system shall
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add Wants dependencies to
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this unit for their unit during
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installation.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><filename>network.target</filename></term>
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<listitem>
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<para>systemd automatically
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adds dependencies of type
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After for this target unit to
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all SysV init script service
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units with an LSB header
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referring to the
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<literal>$network</literal>
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facility.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><filename>nss-lookup.target</filename></term>
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<listitem>
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<para>systemd automatically
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adds dependencies of type
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After for this target unit to
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all SysV init script service
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units with an LSB header
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referring to the
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<literal>$named</literal>
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facility.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><filename>poweroff.target</filename></term>
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<listitem>
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<para>A special target unit
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for shutting down and powering off the system.</para>
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<para>Applications wanting to
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power off the system should start
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this unit.</para>
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<para><filename>runlevel0.target</filename>
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is an alias for this target
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unit, for compatibility with SysV.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><filename>reboot.target</filename></term>
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<listitem>
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<para>A special target unit
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for shutting down and rebooting the system.</para>
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<para>Applications wanting to
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reboot the system should start
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this unit.</para>
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<para><filename>runlevel6.target</filename>
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is an alias for this target
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unit, for compatibility with SysV.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><filename>remote-fs.target</filename></term>
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<listitem>
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<para>Similar to
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<filename>local-fs.target</filename>,
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but for remote mount
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points.</para>
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<para>systemd automatically
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adds dependencies of type
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After for this target unit to
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all SysV init script service
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units with an LSB header
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referring to the
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<literal>$remote_fs</literal>
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facility.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><filename>rescue.target</filename></term>
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<listitem>
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<para>A special target unit
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for setting up the base system
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and a rescue shell.</para>
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<para><filename>runlevel1.target</filename>
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is an alias for this target
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unit, for compatibility with SysV.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><filename>rpcbind.target</filename></term>
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<listitem>
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<para>systemd automatically
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adds dependencies of type
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After for this target unit to
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all SysV init script service
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units with an LSB header
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referring to the
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<literal>$rpcbind</literal>
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facility.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><filename>time-sync.target</filename></term>
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<listitem>
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<para>systemd automatically
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adds dependencies of type
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After for this target unit to
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all SysV init script service
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units with an LSB header
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referring to the
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<literal>$time</literal>
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facility.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><filename>runlevel2.target</filename></term>
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<listitem>
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<para>This is a target that is
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called whenever the SysV
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compatibility code asks for
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runlevel 2. It is a good idea
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to make this an alias for
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(i.e. symlink to)
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<filename>multi-user.target</filename>.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><filename>runlevel3.target</filename></term>
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<listitem>
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<para>This is a target that is
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called whenever the SysV
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compatibility code asks for
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runlevel 3. It is a good idea
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to make this an alias for
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(i.e. symlink to)
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<filename>multi-user.target</filename>
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or
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<filename>graphical.target</filename>.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
|
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<term><filename>runlevel4.target</filename></term>
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<listitem>
|
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<para>This is a target that is
|
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called whenever the SysV
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|
compatibility code asks for
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runlevel 4. It is a good idea
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|
to make this an alias for
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|
(i.e. symlink to)
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<filename>multi-user.target</filename>
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or
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<filename>graphical.target</filename>.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
|
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<term><filename>runlevel5.target</filename></term>
|
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<listitem>
|
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<para>This is a target that is
|
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called whenever the SysV
|
|
compatibility code asks for
|
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runlevel 5. It is a good idea
|
|
to make this an alias for
|
|
(i.e. symlink to)
|
|
<filename>multi-user.target</filename>
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or
|
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<filename>graphical.target</filename>.</para>
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|
</listitem>
|
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</varlistentry>
|
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<varlistentry>
|
|
<term><filename>shutdown.target</filename></term>
|
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<listitem>
|
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<para>A special target unit
|
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that terminates the services
|
|
on system shutdown.</para>
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|
|
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<para>Services that shall be
|
|
terminated on system shutdown
|
|
shall add Conflicts
|
|
dependencies to this unit for
|
|
their service unit, which is
|
|
implicitly done when
|
|
<varname>DefaultDependencies=yes</varname>
|
|
is set (the default).</para>
|
|
|
|
<para>systemd automatically
|
|
adds dependencies of type
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Conflicts to this target unit
|
|
for all SysV init script
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service units that shall be
|
|
terminated in SysV runlevels 0
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or 6.</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><filename>sigpwr.target</filename></term>
|
|
<listitem>
|
|
<para>A special target that is
|
|
started when systemd receives
|
|
the SIGPWR process signal,
|
|
which is normally sent by the
|
|
kernel or UPS daemons when
|
|
power fails.</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><filename>sockets.target</filename></term>
|
|
<listitem>
|
|
<para>A special target unit
|
|
that sets up all service
|
|
sockets.</para>
|
|
|
|
<para>Services that can be
|
|
socket-activated shall add
|
|
Wants dependencies to this
|
|
unit for their socket unit
|
|
during installation.</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><filename>swap.target</filename></term>
|
|
<listitem>
|
|
<para>Similar to
|
|
<filename>local-fs.target</filename>, but for swap
|
|
partitions and swap
|
|
files.</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><filename>sysinit.target</filename></term>
|
|
<listitem>
|
|
<para>A special target unit
|
|
covering early boot-up scripts.</para>
|
|
<para>systemd automatically
|
|
adds dependencies of the types
|
|
Wants and After for all
|
|
SysV service units configured
|
|
for runlevels that are not 0
|
|
to 6 to this target unit.
|
|
This covers the special
|
|
boot-up runlevels some
|
|
distributions have, such as S
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or b.</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><filename>syslog.target</filename></term>
|
|
<listitem>
|
|
<para>systemd automatically
|
|
adds dependencies of type
|
|
After for this target unit to
|
|
all SysV init script service
|
|
units with an LSB header
|
|
referring to the
|
|
<literal>$syslog</literal>
|
|
facility.</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><filename>systemd-initctl.service</filename></term>
|
|
<listitem>
|
|
<para>This provides
|
|
compatibility with the SysV
|
|
/dev/initctl file system FIFO
|
|
for communication with the
|
|
init system.</para>
|
|
<para>This is a
|
|
socket-activated service, see
|
|
<filename>system-initctl.socket</filename>.</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><filename>systemd-initctl.socket</filename></term>
|
|
<listitem>
|
|
<para>Socket activation unit
|
|
for
|
|
<filename>system-initctl.service</filename>.</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><filename>systemd-logger.service</filename></term>
|
|
<listitem>
|
|
<para>This is internally used
|
|
by systemd to provide syslog
|
|
logging to the processes it
|
|
maintains.</para>
|
|
<para>This is a
|
|
socket-activated service, see
|
|
<filename>system-logger.socket</filename>.</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><filename>systemd-logger.socket</filename></term>
|
|
<listitem>
|
|
<para>Socket activation unit
|
|
for
|
|
<filename>system-logger.service</filename>. systemd
|
|
will automatically add
|
|
dependencies of types Requires
|
|
and After to all units that
|
|
have been configured for
|
|
stdout or stderr to be
|
|
connected to syslog or the
|
|
kernel log buffer.</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><filename>systemd-shutdownd.service</filename></term>
|
|
<listitem>
|
|
<para>This is internally used
|
|
by
|
|
<citerefentry><refentrytitle>shutdown</refentrytitle><manvolnum>8</manvolnum></citerefentry>
|
|
to implement delayed shutdowns.</para>
|
|
<para>This is a
|
|
socket-activated service, see
|
|
<filename>system-shutdownd.socket</filename>.</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><filename>systemd-shutdownd.socket</filename></term>
|
|
<listitem>
|
|
<para>Socket activation unit
|
|
for
|
|
<filename>system-shutdownd.service</filename>.</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
<varlistentry>
|
|
<term><filename>umount.target</filename></term>
|
|
<listitem>
|
|
<para>A special target unit
|
|
that umounts all mount and
|
|
automount points on system
|
|
shutdown.</para>
|
|
|
|
<para>Mounts that shall be
|
|
unmounted on system shutdown
|
|
shall add Conflicts
|
|
dependencies to this unit for
|
|
their mount unit, which is
|
|
implicitly done when
|
|
<varname>DefaultDependencies=yes</varname>
|
|
is set (the default).</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>Special User Units</title>
|
|
|
|
<para>When systemd runs as a user instance, the
|
|
following special units are available, which have
|
|
similar definitions as their system counterparts:
|
|
<filename>default.target</filename>,
|
|
<filename>local-fs.target</filename>,
|
|
<filename>remote-fs.target</filename>,
|
|
<filename>shutdown.target</filename>,
|
|
<filename>sockets.target</filename>,
|
|
<filename>swap.target</filename>.</para>
|
|
|
|
<para>In addition the following special unit is
|
|
understood only when systemd runs as service instance:</para>
|
|
|
|
<variablelist>
|
|
<varlistentry>
|
|
<term><filename>exit.service</filename></term>
|
|
<listitem>
|
|
<para>A special service unit
|
|
for shutting down the
|
|
user service manager.</para>
|
|
|
|
<para>Applications wanting to
|
|
terminate the user service
|
|
manager should start this
|
|
unit. If systemd receives
|
|
SIGTERM or SIGINT when running
|
|
as user service daemon it will
|
|
start this unit.</para>
|
|
|
|
<para>Normally, this pulls in
|
|
<filename>shutdown.target</filename>
|
|
which in turn should be
|
|
conflicted by all units that
|
|
want to be shut down on
|
|
user service manager exit.</para>
|
|
</listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>See Also</title>
|
|
<para>
|
|
<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
|
|
<citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
|
|
<citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
|
|
<citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>
|
|
</para>
|
|
</refsect1>
|
|
|
|
</refentry>
|