systemd.xml revision 4cf0b03b976dd7050595f835092b551623468dbe
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen<?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen This file is part of systemd.
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen Copyright 2010 Lennart Poettering
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen systemd is free software; you can redistribute it and/or modify it
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen under the terms of the GNU Lesser General Public License as published by
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen the Free Software Foundation; either version 2.1 of the License, or
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen (at your option) any later version.
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen systemd is distributed in the hope that it will be useful, but
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen WITHOUT ANY WARRANTY; without even the implied warranty of
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen Lesser General Public License for more details.
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen You should have received a copy of the GNU Lesser General Public License
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen along with systemd; If not, see <http://www.gnu.org/licenses/>.
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering xmlns:xi="http://www.w3.org/2001/XInclude">
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <refentryinfo>
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <authorgroup>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </authorgroup>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </refentryinfo>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <refpurpose>systemd system and service manager</refpurpose>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <refsynopsisdiv>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <command>systemd <arg choice="opt" rep="repeat">OPTIONS</arg></command>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </cmdsynopsis>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <command>init <arg choice="opt" rep="repeat">OPTIONS</arg> <arg choice="req">COMMAND</arg></command>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </cmdsynopsis>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </refsynopsisdiv>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <para>systemd is a system and service manager for Linux operating
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering systems. When run as first process on boot (as PID 1), it acts as
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering init system that brings up and maintains userspace
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering services.</para>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <para>For compatibility with SysV, if systemd is called as
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <command>init</command> and a PID that is not 1, it will execute
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <command>telinit</command> and pass all command line arguments
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering unmodified. That means <command>init</command> and
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <command>telinit</command> are mostly equivalent when invoked from
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering normal login sessions. See
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <citerefentry><refentrytitle>telinit</refentrytitle><manvolnum>8</manvolnum></citerefentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering for more information.</para>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <para>When run as a system instance, systemd interprets the
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering configuration file <filename>system.conf</filename> and the files
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering in <filename>system.conf.d</filename> directories; when run as a
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering user instance, systemd interprets the configuration file
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <filename>user.conf</filename> and the files in
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <filename>user.conf.d</filename> directories. See
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering for more information.</para>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <para>The following options are understood:</para>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <variablelist>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>Determine startup sequence, dump it and exit.
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering This is an option useful for debugging only.</para></listitem>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><option>--dump-configuration-items</option></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>Dump understood unit configuration items. This
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering outputs a terse but complete list of configuration items
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering understood in unit definition files.</para></listitem>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>Set default unit to activate on startup. If
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering not specified, defaults to
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <filename>default.target</filename>.</para></listitem>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>For <option>--system</option>, tell systemd to
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering run a system instance, even if the process ID is not 1, i.e.
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering systemd is not run as init process. <option>--user</option>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering does the opposite, running a user instance even if the process
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering ID is 1. Normally it should not be necessary to pass these
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering options, as systemd automatically detects the mode it is
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering started in. These options are hence of little use except for
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering debugging. Note that it is not supported booting and
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering maintaining a full system with systemd running in
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <option>--system</option> mode, but PID not 1. In practice,
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering passing <option>--system</option> explicitly is only useful in
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering conjunction with <option>--test</option>.</para></listitem>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><option>--dump-core</option></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>Enable core dumping on crash. This switch has
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering no effect when running as user instance. This setting may also
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering be enabled during boot on the kernel command line via the
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varname>systemd.dump_core=</varname> option, see
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><option>--crash-vt=</option><replaceable>VT</replaceable></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>Switch to a specific virtual console (VT) on
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering crash. Takes a positive integer in the range 1..63, or a
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering boolean argument. If an integer is passed, selects which VT to
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering switch to. If <constant>yes</constant>, the VT kernel messages
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering are written to is selected. If <constant>no</constant>, no VT
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering switch is attempted. This switch has no effect when running as
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering user instance. This setting may also be enabled during boot,
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering on the kernel command line via the
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varname>systemd.crash_vt=</varname> option, see
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><option>--crash-shell</option></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>Run a shell on crash. This switch has no
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering effect when running as user instance. This setting may also be
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering enabled during boot, on the kernel command line via the
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varname>systemd.crash_shell=</varname> option, see
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><option>--crash-reboot</option></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>Automatically reboot the system on crash. This
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering switch has no effect when running as user instance. This
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering setting may also be enabled during boot, on the kernel command
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering line via the <varname>systemd.crash_reboot=</varname> option,
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><option>--confirm-spawn</option></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>Ask for confirmation when spawning processes.
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering This switch has no effect when run as user
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><option>--show-status=</option></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>Show terse service status information while
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering booting. This switch has no effect when run as user instance.
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering Takes a boolean argument which may be omitted which is
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering interpreted as <option>true</option>.</para></listitem>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><option>--log-target=</option></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>Set log target. Argument must be one of
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><option>--log-level=</option></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering argument this accepts a numerical log
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering level or the well-known <citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering symbolic names (lowercase):
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <option>debug</option>.</para></listitem>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><option>--log-color=</option></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>Highlight important log messages. Argument is
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering a boolean value. If the argument is omitted, it defaults to
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><option>--log-location=</option></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>Include code location in log messages. This is
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering mostly relevant for debugging purposes. Argument is a boolean
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering value. If the argument is omitted it defaults to
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><option>--default-standard-output=</option></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><option>--default-standard-error=</option></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>Sets the default output or error output for
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering all services and sockets, respectively. That is, controls the
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering default for <option>StandardOutput=</option> and
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering for details). Takes one of
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering argument is omitted
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <option>--default-standard-output=</option> defaults to
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <option>--default-standard-error=</option> to
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <option>inherit</option>.</para></listitem>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <xi:include href="standard-options.xml" xpointer="help" />
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <xi:include href="standard-options.xml" xpointer="version" />
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </variablelist>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <para>systemd provides a dependency system between various
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering entities called "units" of 12 different types. Units encapsulate
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering various objects that are relevant for system boot-up and
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering maintenance. The majority of units are configured in unit
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering configuration files, whose syntax and basic set of options is
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering however some are created automatically from other configuration,
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering dynamically from system state or programmatically at runtime.
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering Units may be "active" (meaning started, bound, plugged in, ...,
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering depending on the unit type, see below), or "inactive" (meaning
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering stopped, unbound, unplugged, ...), as well as in the process of
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering being activated or deactivated, i.e. between the two states (these
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering states are called "activating", "deactivating"). A special
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering "failed" state is available as well, which is very similar to
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering "inactive" and is entered when the service failed in some way
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering (process returned error code on exit, or crashed, or an operation
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering timed out). If this state is entered, the cause will be logged,
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering for later reference. Note that the various unit types may have a
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering number of additional substates, which are mapped to the five
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering generalized unit states described here.</para>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <para>The following unit types are available:</para>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>Service units, which start and control daemons
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering and the processes they consist of. For details see
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>Socket units, which encapsulate local IPC or
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering network sockets in the system, useful for socket-based
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering activation. For details about socket units see
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering for details on socket-based activation and other forms of
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering activation, see
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <citerefentry><refentrytitle>daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para></listitem>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>Target units are useful to group units, or
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering provide well-known synchronization points during boot-up, see
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <listitem><para>Device units expose kernel devices in systemd
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen and may be used to implement device-based activation. For
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <listitem><para>Mount units control mount points in the file
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering system, for details see
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <listitem><para>Automount units provide automount capabilities,
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering for on-demand mounting of file systems as well as parallelized
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <citerefentry><refentrytitle>systemd.automount</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <listitem><para>Snapshot units can be used to temporarily save
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering the state of the set of systemd units, which later may be
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen restored by activating the saved snapshot unit. For more
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen information see
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <citerefentry><refentrytitle>systemd.snapshot</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>Timer units are useful for triggering activation
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering of other units based on timers. You may find details in
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>Swap units are very similar to mount units and
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering encapsulate memory swap partitions or files of the operating
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen system. They are described in
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <listitem><para>Path units may be used to activate other
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen services when file system objects change or are modified. See
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <citerefentry><refentrytitle>systemd.path</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <listitem><para>Slice units may be used to group units which
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen manage system processes (such as service and scope units) in a
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen hierarchical tree for resource management purposes. See
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <listitem><para>Scope units are similar to service units, but
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen manage foreign processes instead of starting them as well. See
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen </orderedlist>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <para>Units are named as their configuration files. Some units
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen have special semantics. A detailed list is available in
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <para>systemd knows various kinds of dependencies, including
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen positive and negative requirement dependencies (i.e.
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <varname>Requires=</varname> and <varname>Conflicts=</varname>) as
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering well as ordering dependencies (<varname>After=</varname> and
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varname>Before=</varname>). NB: ordering and requirement
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering dependencies are orthogonal. If only a requirement dependency
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering exists between two units (e.g. <filename>foo.service</filename>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering requires <filename>bar.service</filename>), but no ordering
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering dependency (e.g. <filename>foo.service</filename> after
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <filename>bar.service</filename>) and both are requested to start,
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen they will be started in parallel. It is a common pattern that both
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering requirement and ordering dependencies are placed between two
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering units. Also note that the majority of dependencies are implicitly
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering created and maintained by systemd. In most cases, it should be
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering unnecessary to declare additional dependencies manually, however
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering it is possible to do this.</para>
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <para>Application programs and units (via dependencies) may
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen request state changes of units. In systemd, these requests are
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen encapsulated as 'jobs' and maintained in a job queue. Jobs may
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering succeed or can fail, their execution is ordered based on the
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen ordering dependencies of the units they have been scheduled
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <para>On boot systemd activates the target unit
e9f3d2d508bfd9fb5b54e82994bda365a71eb864Zbigniew Jędrzejewski-Szmek <filename>default.target</filename> whose job is to activate
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering on-boot services and other on-boot units by pulling them in via
e9f3d2d508bfd9fb5b54e82994bda365a71eb864Zbigniew Jędrzejewski-Szmek dependencies. Usually the unit name is just an alias (symlink) for
987d561fe202568c0a2880cf047c7833fd365c7aLennart Poettering either <filename>graphical.target</filename> (for fully-featured
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen boots into the UI) or <filename>multi-user.target</filename> (for
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen limited console-only boots for use in embedded or server
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen environments, or similar; a subset of graphical.target). However,
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering it is at the discretion of the administrator to configure it as an
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen alias to any other target unit. See
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen for details about these target units.</para>
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <para>Processes systemd spawns are placed in individual Linux
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen control groups named after the unit which they belong to in the
c92e531c82a9815ec349aa1bf31236b86b2d5311Lennart Poettering private systemd hierarchy. (see <ulink
c92e531c82a9815ec349aa1bf31236b86b2d5311Lennart Poettering url="https://www.kernel.org/doc/Documentation/cgroups/cgroups.txt">cgroups.txt</ulink>
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen for more information about control groups, or short "cgroups").
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen systemd uses this to effectively keep track of processes. Control
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen group information is maintained in the kernel, and is accessible
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen via the file system hierarchy (beneath
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <filename>/sys/fs/cgroup/systemd/</filename>), or in tools such as
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <citerefentry project='man-pages'><refentrytitle>systemd-cgls</refentrytitle><manvolnum>1</manvolnum></citerefentry>
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <citerefentry project='man-pages'><refentrytitle>ps</refentrytitle><manvolnum>1</manvolnum></citerefentry>
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen (<command>ps xawf -eo pid,user,cgroup,args</command> is
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen particularly useful to list all processes and the systemd units
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen they belong to.).</para>
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <para>systemd is compatible with the SysV init system to a large
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen degree: SysV init scripts are supported and simply read as an
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen alternative (though limited) configuration file format. The SysV
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <filename>/dev/initctl</filename> interface is provided, and
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen compatibility implementations of the various SysV client tools are
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen available. In addition to that, various established Unix
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen functionality such as <filename>/etc/fstab</filename> or the
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <filename>utmp</filename> database are supported.</para>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <para>systemd has a minimal transaction system: if a unit is
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering requested to start up or shut down it will add it and all its
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering dependencies to a temporary transaction. Then, it will verify if
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering the transaction is consistent (i.e. whether the ordering of all
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering units is cycle-free). If it is not, systemd will try to fix it up,
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering and removes non-essential jobs from the transaction that might
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering remove the loop. Also, systemd tries to suppress non-essential
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering jobs in the transaction that would stop a running service. Finally
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering it is checked whether the jobs of the transaction contradict jobs
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering that have already been queued, and optionally the transaction is
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering aborted then. If all worked out and the transaction is consistent
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering and minimized in its impact it is merged with all already
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering outstanding jobs and added to the run queue. Effectively this
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering means that before executing a requested operation, systemd will
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen verify that it makes sense, fixing it if possible, and only
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen failing if it really cannot work.</para>
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <para>Systemd contains native implementations of various tasks
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen that need to be executed as part of the boot process. For example,
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen it sets the hostname or configures the loopback network device. It
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering also sets up and mounts various API file systems, such as
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <filename>/sys</filename> or <filename>/proc</filename>.</para>
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <para>For more information about the concepts and
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering ideas behind systemd, please refer to the
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <ulink url="http://0pointer.de/blog/projects/systemd.html">Original Design Document</ulink>.</para>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <para>Note that some but not all interfaces provided
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering by systemd are covered by the
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <ulink url="http://www.freedesktop.org/wiki/Software/systemd/InterfaceStabilityPromise">Interface
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <para>Units may be generated dynamically at boot and system
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering manager reload time, for example based on other configuration
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering files or parameters passed on the kernel command line. For details see
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <citerefentry><refentrytitle>systemd.generator</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <para>Systems which invoke systemd in a container or initrd
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering environment should implement the
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <ulink url="http://www.freedesktop.org/wiki/Software/systemd/ContainerInterface">Container Interface</ulink> or
096b6773886bd7a0c8c97aa684b0b67dfae58355Lennart Poettering <ulink url="http://www.freedesktop.org/wiki/Software/systemd/InitrdInterface">initrd Interface</ulink>
096b6773886bd7a0c8c97aa684b0b67dfae58355Lennart Poettering specifications, respectively.</para>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <variablelist>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <listitem><para>The systemd system manager reads unit
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering configuration from various directories. Packages that want to
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen install unit files shall place them in the directory returned
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering by <command>pkg-config systemd
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering --variable=systemdsystemunitdir</command>. Other directories
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen checked are <filename>/usr/local/lib/systemd/system</filename>
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen and <filename>/usr/lib/systemd/system</filename>. User
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering configuration always takes precedence. <command>pkg-config
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering systemd --variable=systemdsystemconfdir</command> returns the
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering path of the system configuration directory. Packages should
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen alter the content of these directories only with the
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <command>enable</command> and <command>disable</command>
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen commands of the
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen tool. Full list of directories is provided in
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen </varlistentry>
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen </variablelist>
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <variablelist>
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>Similar rules apply for the user unit
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen directories. However, here the
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <ulink url="http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html">XDG
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen Base Directory specification</ulink> is followed to find
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering units. Applications should place their unit files in the
b686acb27ea4de042320fa196cfb14e08f30165bTom Gundersen directory returned by <command>pkg-config systemd
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen --variable=systemduserunitdir</command>. Global configuration
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen is done in the directory reported by <command>pkg-config
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen systemd --variable=systemduserconfdir</command>. The
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <command>enable</command> and <command>disable</command>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering commands of the
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering tool can handle both global (i.e. for all users) and private
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen (for one user) enabling/disabling of units. Full list of
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen directories is provided in
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen </varlistentry>
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen </variablelist>
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <variablelist>
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <varlistentry>
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <listitem><para>The location of the SysV init script directory
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen varies between distributions. If systemd cannot find a native
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen unit file for a requested service, it will look for a SysV
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen init script of the same name (with the
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen </variablelist>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <variablelist>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <term>SysV runlevel link farm directory</term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>The location of the SysV runlevel link farm
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen directory varies between distributions. systemd will take the
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering link farm into account when figuring out whether a service
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering shall be enabled. Note that a service unit with a native unit
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering configuration file cannot be started by activating it in the
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering SysV runlevel link farm.</para></listitem>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </variablelist>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <variablelist>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><constant>SIGTERM</constant></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>Upon receiving this signal the systemd system
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen manager serializes its state, reexecutes itself and
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering deserializes the saved state again. This is mostly equivalent
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering to <command>systemctl daemon-reexec</command>.</para>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <para>systemd user managers will start the
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <filename>exit.target</filename> unit when this signal is
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering received. This is mostly equivalent to <command>systemctl
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering --user start exit.target</command>.</para></listitem>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>Upon receiving this signal the systemd system
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering manager will start the
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <filename>ctrl-alt-del.target</filename> unit. This is mostly
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering equivalent to <command>systemctl start
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering ctl-alt-del.target</command>. If this signal is received more
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering often than 7 times per 2s an immediate reboot is triggered.
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering Note that pressing Ctrl-Alt-Del on the console will trigger
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering this signal. Hence, if a reboot is hanging pressing
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering Ctrl-Alt-Del more than 7 times in 2s is a relatively safe way
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering to trigger an immediate reboot.</para>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <para>systemd user managers treat this signal the same way as
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <constant>SIGTERM</constant>.</para></listitem>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><constant>SIGWINCH</constant></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>When this signal is received the systemd
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering system manager will start the
ad867662936a4c7ab2c7116d804c272338801231Lennart Poettering <filename>kbrequest.target</filename> unit. This is mostly
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering equivalent to <command>systemctl start
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <para>This signal is ignored by systemd user
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>When this signal is received the systemd
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering manager will start the <filename>sigpwr.target</filename>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering unit. This is mostly equivalent to <command>systemctl start
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering sigpwr.target</command>.</para></listitem>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><constant>SIGUSR1</constant></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>When this signal is received the systemd
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering manager will try to reconnect to the D-Bus
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><constant>SIGUSR2</constant></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>When this signal is received the systemd
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering manager will log its complete state in human readable form.
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering The data logged is the same as printed by
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <command>systemd-analyze dump</command>.</para></listitem>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>Reloads the complete daemon configuration.
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering This is mostly equivalent to <command>systemctl
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><constant>SIGRTMIN+0</constant></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>Enters default mode, starts the
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <filename>default.target</filename> unit. This is mostly
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering equivalent to <command>systemctl start
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering default.target</command>.</para></listitem>
ad867662936a4c7ab2c7116d804c272338801231Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><constant>SIGRTMIN+1</constant></term>
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <listitem><para>Enters rescue mode, starts the
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <filename>rescue.target</filename> unit. This is mostly
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering equivalent to <command>systemctl isolate
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering rescue.target</command>.</para></listitem>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><constant>SIGRTMIN+2</constant></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>Enters emergency mode, starts the
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <filename>emergency.service</filename> unit. This is mostly
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering equivalent to <command>systemctl isolate
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering emergency.service</command>.</para></listitem>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><constant>SIGRTMIN+3</constant></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>Halts the machine, starts the
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <filename>halt.target</filename> unit. This is mostly
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering equivalent to <command>systemctl start
3cb10d3a0b1b6a7c44f307f2abb5215104e16941Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><constant>SIGRTMIN+4</constant></term>
ad867662936a4c7ab2c7116d804c272338801231Lennart Poettering <listitem><para>Powers off the machine, starts the
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <filename>poweroff.target</filename> unit. This is mostly
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen equivalent to <command>systemctl start
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering poweroff.target</command>.</para></listitem>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>Reboots the machine, starts the
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <filename>reboot.target</filename> unit. This is mostly
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering equivalent to <command>systemctl start
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering reboot.target</command>.</para></listitem>
3cb10d3a0b1b6a7c44f307f2abb5215104e16941Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><constant>SIGRTMIN+6</constant></term>
ad867662936a4c7ab2c7116d804c272338801231Lennart Poettering <listitem><para>Reboots the machine via kexec, starts the
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <filename>kexec.target</filename> unit. This is mostly
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering equivalent to <command>systemctl start
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering kexec.target</command>.</para></listitem>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>Immediately halts the machine.</para></listitem>
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><constant>SIGRTMIN+14</constant></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>Immediately powers off the machine.</para></listitem>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><constant>SIGRTMIN+15</constant></term>
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <listitem><para>Immediately reboots the machine.</para></listitem>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><constant>SIGRTMIN+16</constant></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>Immediately reboots the machine with kexec.</para></listitem>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><constant>SIGRTMIN+20</constant></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>Enables display of status messages on the
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering console, as controlled via
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <varname>systemd.show_status=1</varname> on the kernel command
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><constant>SIGRTMIN+21</constant></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering status messages on the console, as
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering controlled via
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering on the kernel command
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><constant>SIGRTMIN+22</constant></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><constant>SIGRTMIN+23</constant></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>Sets the log level to <literal>debug</literal>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <constant>SIGRTMIN+23</constant>), as controlled via
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varname>systemd.log_level=debug</varname> (or
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varname>systemd.log_level=info</varname> on
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <constant>SIGRTMIN+23</constant>) on the kernel command
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><constant>SIGRTMIN+24</constant></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>Immediately exits the manager (only available
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><constant>SIGRTMIN+26</constant></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><constant>SIGRTMIN+27</constant></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><constant>SIGRTMIN+28</constant></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <constant>SIGRTMIN+27</constant>, <literal>kmsg</literal> on
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <constant>SIGRTMIN+28</constant>), as controlled via
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <varname>systemd.log_target=journal-or-kmsg</varname> (or
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <varname>systemd.log_target=console</varname> on
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varname>systemd.log_target=kmsg</varname> on
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <constant>SIGRTMIN+28</constant>) on the kernel command
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen </variablelist>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <variablelist class='environment-variables'>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><varname>$SYSTEMD_LOG_LEVEL</varname></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>systemd reads the log level from this
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering environment variable. This can be overridden with
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <option>--log-level=</option>.</para></listitem>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><varname>$SYSTEMD_LOG_TARGET</varname></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>systemd reads the log target from this
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering environment variable. This can be overridden with
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <option>--log-target=</option>.</para></listitem>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><varname>$SYSTEMD_LOG_COLOR</varname></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>Controls whether systemd highlights important
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering log messages. This can be overridden with
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <option>--log-color=</option>.</para></listitem>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><varname>$SYSTEMD_LOG_LOCATION</varname></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>Controls whether systemd prints the code
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering location along with log messages. This can be overridden with
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <option>--log-location=</option>.</para></listitem>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><varname>$XDG_CONFIG_HOME</varname></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><varname>$XDG_CONFIG_DIRS</varname></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><varname>$XDG_DATA_HOME</varname></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><varname>$XDG_DATA_DIRS</varname></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>The systemd user manager uses these variables
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering in accordance to the <ulink
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering url="http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html">XDG
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering Base Directory specification</ulink> to find its
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><varname>$SYSTEMD_UNIT_PATH</varname></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>Controls where systemd looks for unit
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><varname>$SYSTEMD_SYSVINIT_PATH</varname></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>Controls where systemd looks for SysV init
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><varname>$SYSTEMD_SYSVRCND_PATH</varname></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>Controls where systemd looks for SysV init
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering script runlevel link farms.</para></listitem>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><varname>$LISTEN_PID</varname></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><varname>$LISTEN_FDS</varname></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><varname>$LISTEN_FDNAMES</varname></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>Set by systemd for supervised processes during
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering socket-based activation. See
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><varname>$NOTIFY_SOCKET</varname></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>Set by systemd for supervised processes for
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering status and start-up completion notification. See
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </variablelist>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <para>When run as system instance systemd parses a number of
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering kernel command line arguments<footnote><para>If run inside a Linux
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering container these arguments may be passed as command line arguments
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering to systemd itself, next to any of the command line options listed
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering in the Options section above. If run outside of Linux containers,
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering these arguments are parsed from <filename>/proc/cmdline</filename>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <variablelist class='kernel-commandline-options'>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><varname>systemd.unit=</varname></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <term><varname>rd.systemd.unit=</varname></term>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <listitem><para>Overrides the unit to activate on boot.
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering Defaults to <filename>default.target</filename>. This may be
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering used to temporarily boot into a different boot unit, for
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering example <filename>rescue.target</filename> or
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <filename>emergency.service</filename>. See
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering for details about these units. The option prefixed with
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <literal>rd.</literal> is honored only in the initial RAM disk
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering (initrd), while the one that is not prefixed only in the main
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering </varlistentry>
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering <varlistentry>
091a364c802e34a58f3260c9cb5db9b75c62215cTom Gundersen <term><varname>systemd.dump_core=</varname></term>
<citerefentry project='man-pages'><refentrytitle>locale.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
<citerefentry project='man-pages'><refentrytitle>locale</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
<citerefentry><refentrytitle>kernel-command-line</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
<citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem>
<citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry project='man-pages'><refentrytitle>locale.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>kernel-command-line</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
<citerefentry project='man-pages'><refentrytitle>bootup</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>