chiark / gitweb /
util: make http url validity checks more generic, and move them to util.c
[elogind.git] / man / systemd.xml
index b4a7e3e..e0e8d37 100644 (file)
@@ -8,20 +8,21 @@
   Copyright 2010 Lennart Poettering
 
   systemd is free software; you can redistribute it and/or modify it
-  under the terms of the GNU General Public License as published by
-  the Free Software Foundation; either version 2 of the License, or
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
   (at your option) any later version.
 
   systemd is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
-  General Public License for more details.
+  Lesser General Public License for more details.
 
-  You should have received a copy of the GNU General Public License
+  You should have received a copy of the GNU Lesser General Public License
   along with systemd; If not, see <http://www.gnu.org/licenses/>.
 -->
 
-<refentry id="systemd">
+<refentry id="systemd"
+          xmlns:xi="http://www.w3.org/2001/XInclude">
 
         <refentryinfo>
                 <title>systemd</title>
@@ -45,7 +46,7 @@
         <refnamediv>
                 <refname>systemd</refname>
                 <refname>init</refname>
-                <refpurpose>systemd System and Session Manager</refpurpose>
+                <refpurpose>systemd system and service manager</refpurpose>
         </refnamediv>
 
         <refsynopsisdiv>
@@ -60,7 +61,7 @@
         <refsect1>
                 <title>Description</title>
 
-                <para>systemd is a system and session manager for
+                <para>systemd is a system and service manager for
                 Linux operating systems. When run as first process on
                 boot (as PID 1), it acts as init system that brings
                 up and maintains userspace services.</para>
                 are mostly equivalent when invoked from normal login sessions. See
                 <citerefentry><refentrytitle>telinit</refentrytitle><manvolnum>8</manvolnum></citerefentry>
                 for more information.</para>
+
+                <para>When run as a system instance, systemd interprets the
+                configuration file <filename>system.conf</filename> and the
+                files in <filename>system.conf.d</filename> directories; when
+                run as a user instance, systemd interprets the configuration
+                file <filename>user.conf</filename> and the files in
+                <filename>user.conf.d</filename> directories. See
+                <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+                for more information.</para>
         </refsect1>
 
         <refsect1>
 
                 <variablelist>
                         <varlistentry>
-                                <term><option>-h</option></term>
-                                <term><option>--help</option></term>
+                                <term><option>--test</option></term>
+
+                                <listitem><para>Determine startup
+                                sequence, dump it and exit. This is an
+                                option useful for debugging
+                                only.</para></listitem>
+                        </varlistentry>
+                        <varlistentry>
+                                <term><option>--dump-configuration-items</option></term>
 
-                                <listitem><para>Prints a short help
-                                text and exits.</para></listitem>
+                                <listitem><para>Dump understood unit
+                                configuration items. This outputs a
+                                terse but complete list of
+                                configuration items understood in unit
+                                definition files.</para></listitem>
                         </varlistentry>
                         <varlistentry>
                                 <term><option>--unit=</option></term>
 
                                 <listitem><para>Set default unit to
-                                activate on startup. If not specified
+                                activate on startup. If not specified,
                                 defaults to
                                 <filename>default.target</filename>.</para></listitem>
                         </varlistentry>
                         <varlistentry>
-                                <term><option>--running-as=</option></term>
-
-                                <listitem><para>Tell systemd to run in
-                                a particular mode. Argument is one of
-                                <option>system</option>,
-                                <option>session</option>. Normally it
-                                should not be necessary to pass this
-                                option, as systemd automatically
-                                detects the mode it is started
-                                in. This call is hence of little use
-                                except for
-                                debugging.</para></listitem>
+                                <term><option>--system</option></term>
+                                <term><option>--user</option></term>
+
+                                <listitem><para>For <option>--system</option>,
+                                tell systemd to run a
+                                system instance, even if the process ID is
+                                not 1, i.e. systemd is not run as init process.
+                                <option>--user</option> does the opposite,
+                                running a user instance even if the process
+                                ID is 1.
+                                Normally it should not be necessary to
+                                pass these options, as systemd
+                                automatically detects the mode it is
+                                started in. These options are hence of
+                                little use except for debugging. Note
+                                that it is not supported booting and
+                                maintaining a full system with systemd
+                                running in <option>--system</option>
+                                mode, but PID not 1. In practice,
+                                passing <option>--system</option> explicitly is
+                                only useful in conjunction with
+                                <option>--test</option>.</para></listitem>
                         </varlistentry>
                         <varlistentry>
-                                <term><option>--test</option></term>
+                                <term><option>--dump-core</option></term>
 
-                                <listitem><para>Determine startup
-                                sequence, dump it and exit. This is an
-                                option useful for debugging
-                                only.</para></listitem>
+                                <listitem><para>Dump core on
+                                crash. This switch has no effect when
+                                run as user
+                                instance.</para></listitem>
                         </varlistentry>
                         <varlistentry>
-                                <term><option>--dump-configuration-items</option></term>
+                                <term><option>--crash-shell</option></term>
 
-                                <listitem><para>Dump understood unit
-                                configuration items. This outputs a
-                                terse but complete list of
-                                configuration items understood in unit
-                                definition files.</para></listitem>
+                                <listitem><para>Run shell on
+                                crash. This switch has no effect when
+                                run as user
+                                instance.</para></listitem>
                         </varlistentry>
                         <varlistentry>
                                 <term><option>--confirm-spawn</option></term>
 
-                                <listitem><para>Ask for confirmation when spawning processes.</para></listitem>
+                                <listitem><para>Ask for confirmation
+                                when spawning processes. This switch
+                                has no effect when run as user
+                                instance.</para></listitem>
+                        </varlistentry>
+                        <varlistentry>
+                                <term><option>--show-status=</option></term>
+
+                                <listitem><para>Show terse service
+                                status information while booting. This
+                                switch has no effect when run as user
+                                instance. Takes a boolean argument
+                                which may be omitted which is
+                                interpreted as
+                                <option>true</option>.</para></listitem>
                         </varlistentry>
                         <varlistentry>
-                                <term><option>--introspect=</option></term>
+                                <term><option>--log-target=</option></term>
 
-                                <listitem><para>Extract D-Bus
-                                interface introspection data. This is
-                                mostly useful at build at install time
-                                to generate data suitable for the
-                                D-Bus interfaces
-                                repository. Optionally the interface
-                                name for the introspection data may be
-                                specified. If omitted, the
-                                introspection data for all interfaces
-                                is dumped.</para></listitem>
+                                <listitem><para>Set log
+                                target. Argument must be one of
+                                <option>console</option>,
+                                <option>journal</option>,
+                                <option>kmsg</option>,
+                                <option>journal-or-kmsg</option>,
+                                <option>null</option>.</para></listitem>
                         </varlistentry>
                         <varlistentry>
                                 <term><option>--log-level=</option></term>
 
                                 <listitem><para>Set log level. As
                                 argument this accepts a numerical log
-                                level or the well-known <citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+                                level or the well-known <citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
                                 symbolic names (lowercase):
                                 <option>emerg</option>,
                                 <option>alert</option>,
                                 <option>debug</option>.</para></listitem>
                         </varlistentry>
                         <varlistentry>
-                                <term><option>--log-target=</option></term>
-
-                                <listitem><para>Set log
-                                target. Argument must be one of
-                                <option>console</option>,
-                                <option>syslog</option>,
-                                <option>kmsg</option>,
-                                <option>syslog-or-kmsg</option>,
-                                <option>null</option>.</para></listitem>
-                        </varlistentry>
-                        <varlistentry>
                                 <term><option>--log-color=</option></term>
 
                                 <listitem><para>Highlight important
                                 log messages. Argument is a boolean
-                                value. If the argument is omitted it
+                                value. If the argument is omitted, it
                                 defaults to
                                 <option>true</option>.</para></listitem>
                         </varlistentry>
                                 it defaults to
                                 <option>true</option>.</para></listitem>
                         </varlistentry>
+                        <varlistentry>
+                                <term><option>--default-standard-output=</option></term>
+                                <term><option>--default-standard-error=</option></term>
+
+                                <listitem><para>Sets the default
+                                output or error output for all
+                                services and sockets, respectively. That is, controls
+                                the default for
+                                <option>StandardOutput=</option>
+                                and <option>StandardError=</option>
+                                (see
+                                <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+                                for details). Takes one of
+                                <option>inherit</option>,
+                                <option>null</option>,
+                                <option>tty</option>,
+                                <option>journal</option>,
+                                <option>journal+console</option>,
+                                <option>syslog</option>,
+                                <option>syslog+console</option>,
+                                <option>kmsg</option>,
+                                <option>kmsg+console</option>.  If the
+                                argument is omitted
+                                <option>--default-standard-output=</option>
+                                defaults to <option>journal</option>
+                                and
+                                <option>--default-standard-error=</option>
+                                to
+                                <option>inherit</option>.</para></listitem>
+                        </varlistentry>
+
+                        <xi:include href="standard-options.xml" xpointer="help" />
+                        <xi:include href="standard-options.xml" xpointer="version" />
                 </variablelist>
         </refsect1>
 
                 <title>Concepts</title>
 
                 <para>systemd provides a dependency system between
-                various entities called "units". Units encapsulate
-                various objects that are relevant for system boot-up
-                and maintainance. The majority of units are configured
-                in unit configuration files, whose syntax and basic
-                set of options is described in
+                various entities called "units" of 12 different
+                types. Units encapsulate various objects that are
+                relevant for system boot-up and maintenance. The
+                majority of units are configured in unit configuration
+                files, whose syntax and basic set of options is
+                described in
                 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
                 however some are created automatically from other
-                configuration or dynamically from system state. Units
-                may be active (meaning started, bound, plugged in, ...
-                depending on the unit type), or inactive (meaning
-                stopped, unbound, unplugged, ...), as well is in the
+                configuration, dynamically from system state or
+                programmatically at runtime. Units may be "active"
+                (meaning started, bound, plugged in, ..., depending on
+                the unit type, see below), or "inactive" (meaning
+                stopped, unbound, unplugged, ...), as well as in the
                 process of being activated or deactivated,
-                i.e. between the two states. The following unit types
-                are available:</para>
+                i.e. between the two states (these states are called
+                "activating", "deactivating"). A special "failed"
+                state is available as well, which is very similar to
+                "inactive" and is entered when the service failed in
+                some way (process returned error code on exit, or
+                crashed, or an operation timed out). If this state is
+                entered, the cause will be logged, for later
+                reference. Note that the various unit types may have a
+                number of additional substates, which are mapped to
+                the five generalized unit states described
+                here.</para>
+
+                <para>The following unit types are available:</para>
 
                 <orderedlist>
-                        <listitem><para>Service units, which control
+                        <listitem><para>Service units, which start and control
                         daemons and the processes they consist of. For
                         details see
                         <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
                         systemd units, which later may be restored by
                         activating the saved snapshot unit. For more
                         information see
-                        <citerefentry><refentrytitle>systemd.automount</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
+                        <citerefentry><refentrytitle>systemd.snapshot</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
 
                         <listitem><para>Timer units are useful for
                         triggering activation of other units based on
                         <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
 
                         <listitem><para>Swap units are very similar to
-                        mount units and encapsulated memory swap
+                        mount units and encapsulate memory swap
                         partitions or files of the operating
-                        systemd. They are described in <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
+                        system. They are described in <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
 
                         <listitem><para>Path units may be used
-                        activate other services when file system
+                        to activate other services when file system
                         objects change or are modified. See
                         <citerefentry><refentrytitle>systemd.path</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
 
+                        <listitem><para>Slice units may be used to
+                        group units which manage system processes
+                        (such as service and scope units) in a
+                        hierarchical tree for resource management
+                        purposes. See
+                        <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
+
+                        <listitem><para>Scope units are similar to
+                        service units, but manage foreign processes
+                        instead of starting them as well. See
+                        <citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
+
                 </orderedlist>
 
                 <para>Units are named as their configuration
                 files. Some units have special semantics. A detailed
-                list you may find in
+                list is available in
                 <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
 
+                <para>systemd knows various kinds of dependencies,
+                including positive and negative requirement
+                dependencies (i.e. <varname>Requires=</varname> and
+                <varname>Conflicts=</varname>) as well as ordering
+                dependencies (<varname>After=</varname> and
+                <varname>Before=</varname>). NB: ordering and
+                requirement dependencies are orthogonal. If only a
+                requirement dependency exists between two units
+                (e.g. <filename>foo.service</filename> requires
+                <filename>bar.service</filename>), but no ordering
+                dependency (e.g. <filename>foo.service</filename>
+                after <filename>bar.service</filename>) and both are
+                requested to start, they will be started in
+                parallel. It is a common pattern that both requirement
+                and ordering dependencies are placed between two
+                units. Also note that the majority of dependencies are
+                implicitly created and maintained by systemd. In most
+                cases, it should be unnecessary to declare additional
+                dependencies manually, however it is possible to do
+                this.</para>
+
+                <para>Application programs and units (via
+                dependencies) may request state changes of units. In
+                systemd, these requests are encapsulated as 'jobs' and
+                maintained in a job queue. Jobs may succeed or can
+                fail, their execution is ordered based on the ordering
+                dependencies of the units they have been scheduled
+                for.</para>
+
                 <para>On boot systemd activates the target unit
-                <filename>default.target</filename> whose job it is to
+                <filename>default.target</filename> whose job is to
                 activate on-boot services and other on-boot units by
                 pulling them in via dependencies. Usually the unit
                 name is just an alias (symlink) for either
                 <filename>multi-user.target</filename> (for limited
                 console-only boots for use in embedded or server
                 environments, or similar; a subset of
-                graphical.target). However it is at the discretion of
+                graphical.target). However, it is at the discretion of
                 the administrator to configure it as an alias to any
                 other target unit. See
                 <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>
                 for details about these target units.</para>
 
-                <para>Processes systemd spawns ared placed in
+                <para>Processes systemd spawns are placed in
                 individual Linux control groups named after the unit
                 which they belong to in the private systemd
                 hierarchy. (see <ulink
-                url="http://www.kernel.org/doc/Documentation/cgroups/cgroups.txt">cgroups.txt</ulink>
+                url="https://www.kernel.org/doc/Documentation/cgroups/cgroups.txt">cgroups.txt</ulink>
                 for more information about control groups, or short
                 "cgroups"). systemd uses this to effectively keep
                 track of processes. Control group information is
                 maintained in the kernel, and is accessible via the
                 file system hierarchy (beneath
-                <filename>/cgroup/systemd/</filename>), or in tools
+                <filename>/sys/fs/cgroup/systemd/</filename>), or in tools
                 such as
-                <citerefentry><refentrytitle>ps</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+                <citerefentry project='man-pages'><refentrytitle>ps</refentrytitle><manvolnum>1</manvolnum></citerefentry>
                 (<command>ps xawf -eo pid,user,cgroup,args</command>
                 is particularly useful to list all processes and the
                 systemd units they belong to.).</para>
                 simply read as an alternative (though limited)
                 configuration file format. The SysV
                 <filename>/dev/initctl</filename> interface is
-                provided, and comaptibility implementations of the
-                various SysV client tools available. In addition to
-                that various established Unix functionality such as
+                provided, and compatibility implementations of the
+                various SysV client tools are available. In addition to
+                that, various established Unix functionality such as
                 <filename>/etc/fstab</filename> or the
                 <filename>utmp</filename> database are
                 supported.</para>
 
                 <para>Systemd contains native implementations of
                 various tasks that need to be executed as part of the
-                boot process. For example, it sets the host name or
+                boot process. For example, it sets the hostname or
                 configures the loopback network device. It also sets
                 up and mounts various API file systems, such as
                 <filename>/sys</filename> or
                 <filename>/proc</filename>.</para>
 
                 <para>For more information about the concepts and
-                ideas behind systemd please refer to the <ulink
+                ideas behind systemd, please refer to the <ulink
                 url="http://0pointer.de/blog/projects/systemd.html">Original
                 Design Document</ulink>.</para>
+
+                <para>Note that some but not all interfaces provided
+                by systemd are covered by the <ulink
+                url="http://www.freedesktop.org/wiki/Software/systemd/InterfaceStabilityPromise">Interface
+                Stability Promise</ulink>.</para>
+
+                <para>Units may be generated dynamically at boot and
+                system manager reload time, for example based on other
+                configuration files or parameters passed on the kernel
+                command line. For details see the <ulink
+                url="http://www.freedesktop.org/wiki/Software/systemd/Generators">Generators
+                Specification</ulink>.</para>
+
+                <para>Systems which invoke systemd in a container
+                or initrd environment should implement the
+                <ulink
+                url="http://www.freedesktop.org/wiki/Software/systemd/ContainerInterface">Container
+                Interface</ulink> or <ulink
+                url="http://www.freedesktop.org/wiki/Software/systemd/InitrdInterface">initrd
+                Interface</ulink> specifications, respectively.</para>
         </refsect1>
 
         <refsect1>
                                 <command>pkg-config systemd
                                 --variable=systemdsystemunitdir</command>. Other
                                 directories checked are
-                                <filename>/usr/local/share/systemd/system</filename>
+                                <filename>/usr/local/lib/systemd/system</filename>
                                 and
-                                <filename>/usr/share/systemd/system</filename>. User
+                                <filename>/usr/lib/systemd/system</filename>. User
                                 configuration always takes
                                 precedence. <command>pkg-config
                                 systemd
                                 --variable=systemdsystemconfdir</command>
                                 returns the path of the system
                                 configuration directory. Packages
-                                should alter the content of these directories
-                                only with the
-                                <citerefentry><refentrytitle>systemd-install</refentrytitle><manvolnum>1</manvolnum></citerefentry>
-                                tool.</para></listitem>
+                                should alter the content of these
+                                directories only with the
+                                <command>enable</command> and
+                                <command>disable</command> commands of
+                                the
+                                <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+                                tool. Full list of directories is provided in
+                                <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
+                                </para></listitem>
                         </varlistentry>
                 </variablelist>
 
                 <variablelist>
                         <varlistentry>
-                                <term>Session unit directories</term>
+                                <term>User unit directories</term>
 
                                 <listitem><para>Similar rules apply
-                                for the session unit
+                                for the user unit
                                 directories. However, here the <ulink
                                 url="http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html">XDG
                                 Base Directory specification</ulink>
                                 units. Applications should place their
                                 unit files in the directory returned
                                 by <command>pkg-config systemd
-                                --variable=systemdsessionunitdir</command>. Global
-                                configuration is done in the
-                                directory reported by
-                                <command>pkg-config systemd
-                                --variable=systemdsessionconfdir</command>. The
-                                <citerefentry><refentrytitle>systemd-install</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+                                --variable=systemduserunitdir</command>. Global
+                                configuration is done in the directory
+                                reported by <command>pkg-config
+                                systemd
+                                --variable=systemduserconfdir</command>. The
+                                <command>enable</command> and
+                                <command>disable</command> commands of
+                                the
+                                <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
                                 tool can handle both global (i.e. for
                                 all users) and private (for one user)
                                 enabling/disabling of
-                                units.</para></listitem>
+                                units. Full list of directories is provided in
+                                <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
+                                </para></listitem>
                         </varlistentry>
                 </variablelist>
 
                                 when figuring out whether a service
                                 shall be enabled. Note that a service
                                 unit with a native unit configuration
-                                file can be started by activating it
+                                file cannot be started by activating it
                                 in the SysV runlevel link
                                 farm.</para></listitem>
                         </varlistentry>
 
                 <variablelist>
                         <varlistentry>
-                                <term>SIGTERM</term>
+                                <term><constant>SIGTERM</constant></term>
 
                                 <listitem><para>Upon receiving this
                                 signal the systemd system manager
                                 to <command>systemctl
                                 daemon-reexec</command>.</para>
 
-                                <para>systemd session managers will
+                                <para>systemd user managers will
                                 start the
                                 <filename>exit.target</filename> unit
                                 when this signal is received. This is
                                 mostly equivalent to
-                                <command>systemctl --session start
+                                <command>systemctl --user start
                                 exit.target</command>.</para></listitem>
                         </varlistentry>
 
                         <varlistentry>
-                                <term>SIGINT</term>
+                                <term><constant>SIGINT</constant></term>
 
                                 <listitem><para>Upon receiving this
                                 signal the systemd system manager will
                                 <command>systemctl start
                                 ctl-alt-del.target</command>.</para>
 
-                                <para>systemd session managers
+                                <para>systemd user managers
                                 treat this signal the same way as
-                                SIGTERM.</para></listitem>
+                                <constant>SIGTERM</constant>.</para></listitem>
                         </varlistentry>
 
                         <varlistentry>
-                                <term>SIGWINCH</term>
+                                <term><constant>SIGWINCH</constant></term>
 
                                 <listitem><para>When this signal is
                                 received the systemd system manager
                                 kbrequest.target</command>.</para>
 
                                 <para>This signal is ignored by
-                                systemd session
+                                systemd user
                                 managers.</para></listitem>
                         </varlistentry>
 
                         <varlistentry>
-                                <term>SIGPWR</term>
+                                <term><constant>SIGPWR</constant></term>
 
                                 <listitem><para>When this signal is
                                 received the systemd manager
                         </varlistentry>
 
                         <varlistentry>
-                                <term>SIGUSR1</term>
+                                <term><constant>SIGUSR1</constant></term>
 
                                 <listitem><para>When this signal is
                                 received the systemd manager will try
                         </varlistentry>
 
                         <varlistentry>
-                                <term>SIGUSR2</term>
+                                <term><constant>SIGUSR2</constant></term>
 
                                 <listitem><para>When this signal is
                                 received the systemd manager will log
                                 its complete state in human readable
                                 form. The data logged is the same as
-                                printed by <command>systemctl
+                                printed by <command>systemd-analyze
                                 dump</command>.</para></listitem>
                         </varlistentry>
 
                         <varlistentry>
-                                <term>SIGHUP</term>
+                                <term><constant>SIGHUP</constant></term>
 
                                 <listitem><para>Reloads the complete
                                 daemon configuration. This is mostly
                         </varlistentry>
 
                         <varlistentry>
-                                <term>SIGRTMIN+0</term>
+                                <term><constant>SIGRTMIN+0</constant></term>
 
                                 <listitem><para>Enters default mode, starts the
                                 <filename>default.target</filename>
                         </varlistentry>
 
                         <varlistentry>
-                                <term>SIGRTMIN+1</term>
+                                <term><constant>SIGRTMIN+1</constant></term>
 
                                 <listitem><para>Enters rescue mode,
                                 starts the
                         </varlistentry>
 
                         <varlistentry>
-                                <term>SIGRTMIN+2</term>
+                                <term><constant>SIGRTMIN+2</constant></term>
 
                                 <listitem><para>Enters emergency mode,
                                 starts the
                         </varlistentry>
 
                         <varlistentry>
-                                <term>SIGRTMIN+3</term>
+                                <term><constant>SIGRTMIN+3</constant></term>
 
                                 <listitem><para>Halts the machine,
                                 starts the
                         </varlistentry>
 
                         <varlistentry>
-                                <term>SIGRTMIN+4</term>
+                                <term><constant>SIGRTMIN+4</constant></term>
 
                                 <listitem><para>Powers off the machine,
                                 starts the
                         </varlistentry>
 
                         <varlistentry>
-                                <term>SIGRTMIN+5</term>
+                                <term><constant>SIGRTMIN+5</constant></term>
 
                                 <listitem><para>Reboots the machine,
                                 starts the
                                 <command>systemctl start
                                 reboot.target</command>.</para></listitem>
                         </varlistentry>
+
+                        <varlistentry>
+                                <term><constant>SIGRTMIN+6</constant></term>
+
+                                <listitem><para>Reboots the machine via kexec,
+                                starts the
+                                <filename>kexec.target</filename>
+                                unit. This is mostly equivalent to
+                                <command>systemctl start
+                                kexec.target</command>.</para></listitem>
+                        </varlistentry>
+
+                        <varlistentry>
+                                <term><constant>SIGRTMIN+13</constant></term>
+
+                                <listitem><para>Immediately halts the machine.</para></listitem>
+                        </varlistentry>
+
+                        <varlistentry>
+                                <term><constant>SIGRTMIN+14</constant></term>
+
+                                <listitem><para>Immediately powers off the machine.</para></listitem>
+                        </varlistentry>
+
+                        <varlistentry>
+                                <term><constant>SIGRTMIN+15</constant></term>
+
+                                <listitem><para>Immediately reboots the machine.</para></listitem>
+                        </varlistentry>
+
+                        <varlistentry>
+                                <term><constant>SIGRTMIN+16</constant></term>
+
+                                <listitem><para>Immediately reboots the machine with kexec.</para></listitem>
+                        </varlistentry>
+
+                        <varlistentry>
+                                <term><constant>SIGRTMIN+20</constant></term>
+
+                                <listitem><para>Enables display of
+                                status messages on the console, as
+                                controlled via
+                                <varname>systemd.show_status=1</varname>
+                                on the kernel command
+                                line.</para></listitem>
+                        </varlistentry>
+
+                        <varlistentry>
+                                <term><constant>SIGRTMIN+21</constant></term>
+
+                                <listitem><para>Disables display of
+                                status messages on the console, as
+                                controlled via
+                                <varname>systemd.show_status=0</varname>
+                                on the kernel command
+                                line.</para></listitem>
+                        </varlistentry>
+
+                        <varlistentry>
+                                <term><constant>SIGRTMIN+22</constant></term>
+                                <term><constant>SIGRTMIN+23</constant></term>
+
+                                <listitem><para>Sets the log level to
+                                <literal>debug</literal>
+                                (or <literal>info</literal> on
+                                <constant>SIGRTMIN+23</constant>), as
+                                controlled via
+                                <varname>systemd.log_level=debug</varname>
+                                (or <varname>systemd.log_level=info</varname>
+                                on <constant>SIGRTMIN+23</constant>) on
+                                the kernel command
+                                line.</para></listitem>
+                        </varlistentry>
+
+                        <varlistentry>
+                                <term><constant>SIGRTMIN+24</constant></term>
+
+                                <listitem><para>Immediately exits the
+                                manager (only available for --user
+                                instances).</para></listitem>
+                        </varlistentry>
+
+                        <varlistentry>
+                                <term><constant>SIGRTMIN+26</constant></term>
+                                <term><constant>SIGRTMIN+27</constant></term>
+                                <term><constant>SIGRTMIN+28</constant></term>
+
+                                <listitem><para>Sets the log level to
+                                <literal>journal-or-kmsg</literal> (or
+                                <literal>console</literal> on
+                                <constant>SIGRTMIN+27</constant>,
+                                <literal>kmsg</literal> on
+                                <constant>SIGRTMIN+28</constant>), as
+                                controlled via
+                                <varname>systemd.log_target=journal-or-kmsg</varname>
+                                (or
+                                <varname>systemd.log_target=console</varname>
+                                on <constant>SIGRTMIN+27</constant> or
+                                <varname>systemd.log_target=kmsg</varname>
+                                on <constant>SIGRTMIN+28</constant>)
+                                on the kernel command
+                                line.</para></listitem>
+                        </varlistentry>
                 </variablelist>
         </refsect1>
 
         <refsect1>
                 <title>Environment</title>
 
-                <variablelist>
+                <variablelist class='environment-variables'>
                         <varlistentry>
                                 <term><varname>$SYSTEMD_LOG_LEVEL</varname></term>
                                 <listitem><para>systemd reads the
                                 <term><varname>$XDG_DATA_HOME</varname></term>
                                 <term><varname>$XDG_DATA_DIRS</varname></term>
 
-                                <listitem><para>The systemd session
+                                <listitem><para>The systemd user
                                 manager uses these variables in
                                 accordance to the <ulink
                                 url="http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html">XDG
         </refsect1>
 
         <refsect1>
+                <title>Kernel Command Line</title>
+
+                <para>When run as system instance systemd parses a
+                number of kernel command line
+                arguments<footnote><para>If run inside a Linux
+                container these arguments may be passed as command
+                line arguments to systemd itself, next to any of the
+                command line options listed in the Options section
+                above. If run outside of Linux containers, these
+                arguments are parsed from
+                <filename>/proc/cmdline</filename>
+                instead.</para></footnote>:</para>
+
+                <variablelist class='kernel-commandline-options'>
+                        <varlistentry>
+                                <term><varname>systemd.unit=</varname></term>
+                                <term><varname>rd.systemd.unit=</varname></term>
+
+                                <listitem><para>Overrides the unit to
+                                activate on boot. Defaults to
+                                <filename>default.target</filename>. This
+                                may be used to temporarily boot into a
+                                different boot unit, for example
+                                <filename>rescue.target</filename> or
+                                <filename>emergency.service</filename>. See
+                                <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+                                for details about these units. The
+                                option prefixed with
+                                <literal>rd.</literal> is honored
+                                only in the initial RAM disk (initrd),
+                                while the one that is not prefixed only
+                                in the main system.</para></listitem>
+                        </varlistentry>
+
+                        <varlistentry>
+                                <term><varname>systemd.dump_core=</varname></term>
+
+                                <listitem><para>Takes a boolean
+                                argument. If <option>true</option>,
+                                systemd dumps core when it
+                                crashes. Otherwise, no core dump is
+                                created. Defaults to
+                                <option>true</option>.</para></listitem>
+                        </varlistentry>
+
+                        <varlistentry>
+                                <term><varname>systemd.crash_shell=</varname></term>
+
+                                <listitem><para>Takes a boolean
+                                argument. If <option>true</option>,
+                                systemd spawns a shell when it
+                                crashes. Otherwise, no shell is
+                                spawned. Defaults to
+                                <option>false</option>, for security
+                                reasons, as the shell is not protected
+                                by any password
+                                authentication.</para></listitem>
+                        </varlistentry>
+
+                        <varlistentry>
+                                <term><varname>systemd.crash_chvt=</varname></term>
+
+                                <listitem><para>Takes an integer
+                                argument. If positive systemd
+                                activates the specified virtual
+                                terminal when it crashes. Defaults to
+                                <constant>-1</constant>.</para></listitem>
+                        </varlistentry>
+
+                        <varlistentry>
+                                <term><varname>systemd.confirm_spawn=</varname></term>
+
+                                <listitem><para>Takes a boolean
+                                argument. If <option>true</option>,
+                                asks for confirmation when spawning
+                                processes. Defaults to
+                                <option>false</option>.</para></listitem>
+                        </varlistentry>
+
+                        <varlistentry>
+                                <term><varname>systemd.show_status=</varname></term>
+
+                                <listitem><para>Takes a boolean
+                                argument or the constant
+                                <constant>auto</constant>. If
+                                <option>true</option>, shows terse
+                                service status updates on the console
+                                during bootup.
+                                <constant>auto</constant> behaves like
+                                <option>false</option> until a service
+                                fails or there is a significant delay
+                                in boot. Defaults to
+                                <option>true</option>, unless
+                                <option>quiet</option> is passed as
+                                kernel command line option in which
+                                case it defaults to
+                                <constant>auto</constant>.</para></listitem>
+                        </varlistentry>
+
+                        <varlistentry>
+                                <term><varname>systemd.log_target=</varname></term>
+                                <term><varname>systemd.log_level=</varname></term>
+                                <term><varname>systemd.log_color=</varname></term>
+                                <term><varname>systemd.log_location=</varname></term>
+
+                                <listitem><para>Controls log output,
+                                with the same effect as the
+                                <varname>$SYSTEMD_LOG_TARGET</varname>, <varname>$SYSTEMD_LOG_LEVEL</varname>, <varname>$SYSTEMD_LOG_COLOR</varname>, <varname>$SYSTEMD_LOG_LOCATION</varname>
+                                environment variables described above.</para></listitem>
+                        </varlistentry>
+
+                        <varlistentry>
+                                <term><varname>systemd.default_standard_output=</varname></term>
+                                <term><varname>systemd.default_standard_error=</varname></term>
+                                <listitem><para>Controls default
+                                standard output and error output for
+                                services, with the same effect as the
+                                <option>--default-standard-output=</option>
+                                and <option>--default-standard-error=</option>
+                                command line arguments described
+                                above, respectively.</para></listitem>
+                        </varlistentry>
+
+                        <varlistentry>
+                                <term><varname>systemd.setenv=</varname></term>
+
+                                <listitem><para>Takes a string
+                                argument in the form VARIABLE=VALUE.
+                                May be used to set default environment
+                                variables to add to forked child processes.
+                                May be used more than once to set multiple
+                                variables.</para></listitem>
+                        </varlistentry>
+
+                        <varlistentry>
+                                <term><varname>quiet</varname></term>
+
+                                <listitem><para>Turn off
+                                status output at boot, much like
+                                <varname>systemd.show_status=false</varname>
+                                would. Note that this option is also
+                                read by the kernel itself and disables
+                                kernel log output. Passing this option
+                                hence turns off the usual output from
+                                both the system manager and the kernel.
+                                </para></listitem>
+                        </varlistentry>
+
+                        <varlistentry>
+                                <term><varname>debug</varname></term>
+
+                                <listitem><para>Turn on debugging
+                                output. This is equivalent to
+                                <varname>systemd.log_level=debug</varname>.
+                                Note that this option is also read by
+                                the kernel itself and enables kernel
+                                debug output.  Passing this option
+                                hence turns on the debug output from
+                                both the system manager and the
+                                kernel.</para></listitem>
+                        </varlistentry>
+
+                        <varlistentry>
+                                <term><varname>emergency</varname></term>
+                                <term><varname>-b</varname></term>
+
+                                <listitem><para>Boot into emergency
+                                mode. This is equivalent to
+                                <varname>systemd.unit=emergency.target</varname>
+                                and provided for compatibility reasons
+                                and to be easier to
+                                type.</para></listitem>
+                        </varlistentry>
+
+                        <varlistentry>
+                                <term><varname>rescue</varname></term>
+                                <term><varname>single</varname></term>
+                                <term><varname>s</varname></term>
+                                <term><varname>S</varname></term>
+                                <term><varname>1</varname></term>
+
+                                <listitem><para>Boot into rescue
+                                mode. This is equivalent to
+                                <varname>systemd.unit=rescue.target</varname>
+                                and provided for compatibility reasons
+                                and to be easier to
+                                type.</para></listitem>
+                        </varlistentry>
+
+                        <varlistentry>
+                                <term><varname>2</varname></term>
+                                <term><varname>3</varname></term>
+                                <term><varname>4</varname></term>
+                                <term><varname>5</varname></term>
+
+                                <listitem><para>Boot into the
+                                specified legacy SysV runlevel. These
+                                are equivalent to
+                                <varname>systemd.unit=runlevel2.target</varname>,
+                                <varname>systemd.unit=runlevel3.target</varname>,
+                                <varname>systemd.unit=runlevel4.target</varname>,
+                                and <varname>systemd.unit=runlevel5.target</varname>, respectively,
+                                and provided for compatibility reasons
+                                and to be easier to
+                                type.</para></listitem>
+                        </varlistentry>
+
+                        <varlistentry>
+                                <term><varname>locale.LANG=</varname></term>
+                                <term><varname>locale.LANGUAGE=</varname></term>
+                                <term><varname>locale.LC_CTYPE=</varname></term>
+                                <term><varname>locale.LC_NUMERIC=</varname></term>
+                                <term><varname>locale.LC_TIME=</varname></term>
+                                <term><varname>locale.LC_COLLATE=</varname></term>
+                                <term><varname>locale.LC_MONETARY=</varname></term>
+                                <term><varname>locale.LC_MESSAGES=</varname></term>
+                                <term><varname>locale.LC_PAPER=</varname></term>
+                                <term><varname>locale.LC_NAME=</varname></term>
+                                <term><varname>locale.LC_ADDRESS=</varname></term>
+                                <term><varname>locale.LC_TELEPHONE=</varname></term>
+                                <term><varname>locale.LC_MEASUREMENT=</varname></term>
+                                <term><varname>locale.LC_IDENTIFICATION=</varname></term>
+
+                                <listitem><para>Set the system locale
+                                to use. This overrides the settings in
+                                <filename>/etc/locale.conf</filename>. For
+                                more information see
+                                <citerefentry><refentrytitle>locale.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+                                and
+                                <citerefentry><refentrytitle>locale</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
+                                </para></listitem>
+                        </varlistentry>
+                </variablelist>
+
+                <para>For other kernel command line parameters
+                understood by components of the core OS, please refer
+                to
+                <citerefentry><refentrytitle>kernel-command-line</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
+        </refsect1>
+
+        <refsect1>
                 <title>Sockets and FIFOs</title>
 
                 <variablelist>
                         <varlistentry>
-                                <term><filename>@/org/freedesktop/systemd1/notify</filename></term>
+                                <term><filename>/run/systemd/notify</filename></term>
 
                                 <listitem><para>Daemon status
-                                notification socket. This is an AF_UNIX
-                                datagram socket in the Linux abstract
-                                namespace, and is used to implement
-                                the daemon notification logic as
-                                implemented by
+                                notification socket. This is an
+                                <constant>AF_UNIX</constant> datagram socket and is used to
+                                implement the daemon notification
+                                logic as implemented by
                                 <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem>
 
                         </varlistentry>
 
                         <varlistentry>
-                                <term><filename>@/org/freedesktop/systemd1/logger</filename></term>
+                                <term><filename>/run/systemd/shutdownd</filename></term>
 
                                 <listitem><para>Used internally by the
-                                <filename>systemd-logger.service</filename>
-                                unit to connect STDOUT and/or STDERR
-                                of spawned processes to
-                                <citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
-                                or the kernel log buffer. This is an
-                                AF_UNIX stream socket in the Linux
-                                abstract namespace.</para></listitem>
+                                <citerefentry><refentrytitle>shutdown</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+                                tool to implement delayed
+                                shutdowns. This is an <constant>AF_UNIX</constant> datagram
+                                socket.</para></listitem>
                         </varlistentry>
 
                         <varlistentry>
-                                <term><filename>@/org/freedesktop/systemd1/private</filename></term>
+                                <term><filename>/run/systemd/private</filename></term>
 
                                 <listitem><para>Used internally as
                                 communication channel between
                                 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
                                 and the systemd process. This is an
-                                AF_UNIX stream socket in the Linux
-                                abstract namespace. This interface is
-                                private to systemd and should not be
-                                used in external
+                                <constant>AF_UNIX</constant> stream socket. This interface
+                                is private to systemd and should not
+                                be used in external
                                 projects.</para></listitem>
                         </varlistentry>
 
         <refsect1>
                 <title>See Also</title>
                 <para>
+                        The <ulink url="http://www.freedesktop.org/wiki/Software/systemd/">systemd Homepage</ulink>,
+                        <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+                        <citerefentry><refentrytitle>locale.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
                         <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
-                        <citerefentry><refentrytitle>systemadm</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
-                        <citerefentry><refentrytitle>systemd-install</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+                        <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
                         <citerefentry><refentrytitle>systemd-notify</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
                         <citerefentry><refentrytitle>daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
-                        <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
+                        <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
                         <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
                         <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
-                        <citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</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>
                 </para>
         </refsect1>