chiark / gitweb /
man: mention --runtime where appropriate
[elogind.git] / man / systemd.unit.xml
index 35644d3..d61426a 100644 (file)
@@ -1,6 +1,9 @@
 <?xml version='1.0'?> <!--*-nxml-*-->
 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
-        "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
+        "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" [
+<!ENTITY % entities SYSTEM "custom-entities.ent" >
+%entities;
+]>
 
 <!--
   This file is part of systemd.
         </refnamediv>
 
         <refsynopsisdiv>
-                <para><filename>systemd.service</filename>,
-                <filename>systemd.socket</filename>,
-                <filename>systemd.device</filename>,
-                <filename>systemd.mount</filename>,
-                <filename>systemd.automount</filename>,
-                <filename>systemd.swap</filename>,
-                <filename>systemd.target</filename>,
-                <filename>systemd.path</filename>,
-                <filename>systemd.timer</filename>,
-                <filename>systemd.snapshot</filename></para>
+                <para><filename><replaceable>service</replaceable>.service</filename>,
+                <filename><replaceable>socket</replaceable>.socket</filename>,
+                <filename><replaceable>device</replaceable>.device</filename>,
+                <filename><replaceable>mount</replaceable>.mount</filename>,
+                <filename><replaceable>automount</replaceable>.automount</filename>,
+                <filename><replaceable>swap</replaceable>.swap</filename>,
+                <filename><replaceable>target</replaceable>.target</filename>,
+                <filename><replaceable>path</replaceable>.path</filename>,
+                <filename><replaceable>timer</replaceable>.timer</filename>,
+                <filename><replaceable>snapshot</replaceable>.snapshot</filename>,
+                <filename><replaceable>slice</replaceable>.slice</filename>,
+                <filename><replaceable>scope</replaceable>.scope</filename></para>
+
+                <para><literallayout><filename>/etc/systemd/system/*</filename>
+<filename>/run/systemd/system/*</filename>
+<filename>/usr/lib/systemd/system/*</filename>
+<filename>...</filename>
+                </literallayout></para>
+
+                <para><literallayout><filename>$HOME/.config/systemd/user/*</filename>
+<filename>/etc/systemd/user/*</filename>
+<filename>/run/systemd/user/*</filename>
+<filename>/usr/lib/systemd/user/*</filename>
+<filename>...</filename>
+                </literallayout></para>
         </refsynopsisdiv>
 
         <refsect1>
                 <para>A unit configuration file encodes information
                 about a service, a socket, a device, a mount point, an
                 automount point, a swap file or partition, a start-up
-                target, a file system path or a timer controlled and
-                supervised by
-                <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>. The
-                syntax is inspired by <ulink
+                target, a watched file system path, a timer controlled
+                and supervised by
+                <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+                a temporary system state snapshot, a resource
+                management slice or a group of externally created
+                processes. The syntax is inspired by <ulink
                 url="http://standards.freedesktop.org/desktop-entry-spec/latest/">XDG
-                Desktop Entry Specification</ulink> <filename>.desktop</filename> files, which are in turn
+                Desktop Entry Specification</ulink>
+                <filename>.desktop</filename> files, which are in turn
                 inspired by Microsoft Windows
                 <filename>.ini</filename> files.</para>
 
                 sections of the unit files.</para>
 
                 <para>In addition to the generic [Unit] and [Install]
-                sections described here, each unit should have a
+                sections described here, each unit may have a
                 type-specific section, e.g. [Service] for a service
                 unit. See the respective man pages for more
-                information.</para>
+                information:
+                <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+                <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+                <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+                <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+                <citerefentry><refentrytitle>systemd.automount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+                <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+                <citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+                <citerefentry><refentrytitle>systemd.path</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+                <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+                <citerefentry><refentrytitle>systemd.snapshot</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
+                <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
+                <citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
+                </para>
+
+                <para>Unit files are loaded from a set of paths
+                determined during compilation, described in the next section.
+                </para>
 
                 <para>Unit files may contain additional options on top
                 of those listed here. If systemd encounters an unknown
-                option it will write a warning log message but
+                option, it will write a warning log message but
                 continue loading the unit. If an option is prefixed
-                with <option>X-</option> it is ignored completely by
+                with <option>X-</option>, it is ignored completely by
                 systemd. Applications may use this to include
                 additional information in the unit files.</para>
 
                 written in various formats. For positive settings the
                 strings <option>1</option>, <option>yes</option>,
                 <option>true</option> and <option>on</option> are
-                equivalent. For negative settings the strings
+                equivalent. For negative settings, the strings
                 <option>0</option>, <option>no</option>,
                 <option>false</option> and <option>off</option> are
                 equivalent.</para>
                 <para>Time span values encoded in unit files can be
                 written in various formats. A stand-alone number
                 specifies a time in seconds. If suffixed with a time
-                unit, the unit is honored. A concatenation of
-                multiple values with units is supported, in which case
-                the values are added up. Example: "50" refers to 50
+                unit, the unit is honored. A concatenation of multiple
+                values with units is supported, in which case the
+                values are added up. Example: "50" refers to 50
                 seconds; "2min 200ms" refers to 2 minutes plus 200
                 milliseconds, i.e. 120200ms. The following time units
-                are understood: s, min, h, d, w, ms, us. For details see <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
+                are understood: s, min, h, d, w, ms, us. For details
+                see
+                <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
 
                 <para>Empty lines and lines starting with # or ; are
                 ignored. This may be used for commenting. Lines ending
                 line while reading and the backslash is replaced by a
                 space character. This may be used to wrap long lines.</para>
 
-                <para>If a line starts with <option>.include</option>
-                followed by a file name, the specified file will be
-                parsed at this point. Make sure that the file that is
-                included has the appropriate section headers before
-                any directives.</para>
-
                 <para>Along with a unit file
-                <filename>foo.service</filename> a directory
+                <filename>foo.service</filename>, the directory
                 <filename>foo.service.wants/</filename> may exist. All
-                units symlinked from such a directory are implicitly
-                added as dependencies of type
+                unit files symlinked from such a directory are
+                implicitly added as dependencies of type
                 <varname>Wanted=</varname> to the unit. This is useful
                 to hook units into the start-up of other units,
-                without having to modify their unit configuration
-                files. For details about the semantics of
-                <varname>Wanted=</varname> see below. The preferred
-                way to create symlinks in the
-                <filename>.wants/</filename> directory of a service is
-                with the <command>enable</command> command of the
+                without having to modify their unit files. For details
+                about the semantics of <varname>Wanted=</varname>, see
+                below. The preferred way to create symlinks in the
+                <filename>.wants/</filename> directory of a unit file
+                is with the <command>enable</command> command of the
                 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
                 tool which reads information from the [Install]
-                section of unit files. (See below.) A similar
+                section of unit files (see below). A similar
                 functionality exists for <varname>Requires=</varname>
                 type dependencies as well, the directory suffix is
                 <filename>.requires/</filename> in this case.</para>
 
+                <para>Along with a unit file
+                <filename>foo.service</filename>, a directory
+                <filename>foo.service.d/</filename> may exist. All
+                files with the suffix <literal>.conf</literal> from
+                this directory will be parsed after the file itself is
+                parsed. This is useful to alter or add configuration
+                settings to a unit, without having to modify their
+                unit files. Make sure that the file that is included
+                has the appropriate section headers before any
+                directive.</para>
+
+                <para>If a line starts with <option>.include</option>
+                followed by a filename, the specified file will be
+                parsed at this point. Make sure that the file that is
+                included has the appropriate section headers before
+                any directives.</para>
+
                 <para>Note that while systemd offers a flexible
                 dependency system between units it is recommended to
-                use this functionality only sparsely and instead rely
+                use this functionality only sparingly and instead rely
                 on techniques such as bus-based or socket-based
-                activation which makes dependencies implicit, which
-                both results in a simpler and more flexible
-                system.</para>
+                activation which make dependencies implicit, resulting
+                in a both simpler and more flexible system.</para>
 
                 <para>Some unit names reflect paths existing in the
-                file system name space. Example: a device unit
+                file system namespace. Example: a device unit
                 <filename>dev-sda.device</filename> refers to a device
-                with the device node <filename>/dev/sda</filename> in
-                the file system namespace. If this applies a special
+                with the device node <filename noindex='true'>/dev/sda</filename> in
+                the file system namespace. If this applies, a special
                 way to escape the path name is used, so that the
-                result is usable as part of a file name. Basically,
+                result is usable as part of a filename. Basically,
                 given a path, "/" is replaced by "-", and all
                 unprintable characters and the "-" are replaced by
                 C-style "\x20" escapes. The root directory "/" is
                 <para>Optionally, units may be instantiated from a
                 template file at runtime. This allows creation of
                 multiple units from a single configuration file. If
-                systemd looks for a unit configuration file it will
+                systemd looks for a unit configuration file, it will
                 first search for the literal unit name in the
                 filesystem. If that yields no success and the unit
-                name contains an @ character, systemd will look for a
+                name contains an <literal>@</literal> character, systemd will look for a
                 unit template that shares the same name but with the
-                instance string (i.e. the part between the @ character
+                instance string (i.e. the part between the <literal>@</literal> character
                 and the suffix) removed. Example: if a service
                 <filename>getty@tty3.service</filename> is requested
                 and no file by that name is found, systemd will look
                 <para>To refer to the instance string from
                 within the configuration file you may use the special
                 <literal>%i</literal> specifier in many of the
-                configuration options. Other specifiers exist, the
-                full list is:</para>
+                configuration options. See below for details.</para>
+
+                <para>If a unit file is empty (i.e. has the file size
+                0) or is symlinked to <filename>/dev/null</filename>,
+                its configuration will not be loaded and it appears
+                with a load state of <literal>masked</literal>, and
+                cannot be activated. Use this as an effective way to
+                fully disable a unit, making it impossible to start it
+                even manually.</para>
+
+                <para>The unit file format is covered by the
+                <ulink
+                url="http://www.freedesktop.org/wiki/Software/systemd/InterfaceStabilityPromise">Interface
+                Stability Promise</ulink>.</para>
+
+        </refsect1>
+
+        <refsect1>
+                <title>Unit Load Path</title>
+
+                <para>Unit files are loaded from a set of paths
+                determined during compilation, described in the two
+                tables below. Unit files found in directories listed
+                earlier override files with the same name in
+                directories lower in the list.</para>
+
+                <para>When systemd is running in user mode
+                (<option>--user</option>) and the variable
+                <varname>$SYSTEMD_UNIT_PATH</varname> is set, this
+                contents of this variable overrides the unit load
+                path.
+                </para>
 
                 <table>
-                  <title>Specifiers available in unit files</title>
-                  <tgroup cols='3' align='left' colsep='1' rowsep='1'>
-                    <colspec colname="spec" />
-                    <colspec colname="mean" />
-                    <colspec colname="detail" />
+                  <title>
+                    Load path when running in system mode (<option>--system</option>).
+                  </title>
+
+                  <tgroup cols='2'>
+                    <colspec colname='path' />
+                    <colspec colname='expl' />
                     <thead>
                       <row>
-                        <entry>Specifier</entry>
-                        <entry>Meaning</entry>
-                        <entry>Details</entry>
+                        <entry>Path</entry>
+                        <entry>Description</entry>
                       </row>
                     </thead>
                     <tbody>
                       <row>
-                        <entry><literal>%n</literal></entry>
-                        <entry>Full unit name</entry>
-                        <entry></entry>
+                        <entry><filename>/etc/systemd/system</filename></entry>
+                        <entry>Local configuration</entry>
                       </row>
                       <row>
-                        <entry><literal>%N</literal></entry>
-                        <entry>Unescaped full unit name</entry>
-                        <entry></entry>
-                      </row>
-                      <row>
-                        <entry><literal>%p</literal></entry>
-                        <entry>Prefix name</entry>
-                        <entry>This refers to the string before the @, i.e. "getty" in the example above, where "tty3" is the instance name.</entry>
+                        <entry><filename>/run/systemd/system</filename></entry>
+                        <entry>Runtime units</entry>
                       </row>
                       <row>
-                        <entry><literal>%P</literal></entry>
-                        <entry>Unescaped prefix name</entry>
-                        <entry></entry>
-                      </row>
-                      <row>
-                        <entry><literal>%i</literal></entry>
-                        <entry>Instance name</entry>
-                        <entry>This is the string between the @ character and the suffix.</entry>
-                      </row>
-                      <row>
-                        <entry><literal>%I</literal></entry>
-                        <entry>Unescaped instance name</entry>
-                        <entry></entry>
-                      </row>
-                      <row>
-                        <entry><literal>%f</literal></entry>
-                        <entry>Unescaped file name</entry>
-                        <entry>This is either the unescaped instance name (if set) with / prepended (if necessary), or the prefix name similarly prepended with /.</entry>
-                      </row>
-                      <row>
-                        <entry><literal>%c</literal></entry>
-                        <entry>Control group path of the unit</entry>
-                        <entry></entry>
-                      </row>
-                      <row>
-                        <entry><literal>%r</literal></entry>
-                        <entry>Root control group path of systemd</entry>
-                        <entry></entry>
-                      </row>
-                      <row>
-                        <entry><literal>%R</literal></entry>
-                        <entry>Parent directory of the root control group path of systemd</entry>
-                        <entry></entry>
-                      </row>
-                      <row>
-                        <entry><literal>%t</literal></entry>
-                        <entry>Runtime socket dir</entry>
-                        <entry>This is either /run (for the system manager) or $XDG_RUNTIME_DIR (for user managers).</entry>
-                      </row>
-                      <row>
-                        <entry><literal>%u</literal></entry>
-                        <entry>User name</entry>
-                        <entry>This is the name of the configured user of the unit, or (if none is set) the user running the systemd instance.</entry>
+                        <entry><filename>/usr/lib/systemd/system</filename></entry>
+                        <entry>Units of installed packages</entry>
                       </row>
+                    </tbody>
+                  </tgroup>
+                </table>
+
+                <table>
+                  <title>
+                    Load path when running in user mode (<option>--user</option>).
+                  </title>
+
+                  <tgroup cols='2'>
+                    <colspec colname='path' />
+                    <colspec colname='expl' />
+                    <thead>
                       <row>
-                        <entry><literal>%h</literal></entry>
-                        <entry>User home directory</entry>
-                        <entry>This is the home directory of the configured user of the unit, or (if none is set) the user running the systemd instance.</entry>
+                        <entry>Path</entry>
+                        <entry>Description</entry>
                       </row>
+                    </thead>
+                    <tbody>
                       <row>
-                        <entry><literal>%s</literal></entry>
-                        <entry>User shell</entry>
-                        <entry>This is the shell of the configured user of the unit, or (if none is set) the user running the systemd instance.</entry>
+                        <entry><filename>$HOME/.config/systemd/user</filename></entry>
+                        <entry>User configuration</entry>
                       </row>
                       <row>
-                        <entry><literal>%m</literal></entry>
-                        <entry>Machine ID</entry>
-                        <entry>The machine ID of the running system, formatted as string. See <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry> for more information.</entry>
+                        <entry><filename>/etc/systemd/user</filename></entry>
+                        <entry>Local configuration</entry>
                       </row>
                       <row>
-                        <entry><literal>%b</literal></entry>
-                        <entry>Boot ID</entry>
-                        <entry>The boot ID of the running system, formatted as string. See <citerefentry><refentrytitle>random</refentrytitle><manvolnum>4</manvolnum></citerefentry> for more information.</entry>
+                        <entry><filename>/run/systemd/user</filename></entry>
+                        <entry>Runtime units</entry>
                       </row>
                       <row>
-                        <entry><literal>%H</literal></entry>
-                        <entry>Host name</entry>
-                        <entry>The host name of the running system.</entry>
+                        <entry><filename>/usr/lib/systemd/user</filename></entry>
+                        <entry>Units of installed packages</entry>
                       </row>
                     </tbody>
                   </tgroup>
                 </table>
 
-                <para>If a unit file is empty (i.e. has the file size
-                0) or is symlinked to <filename>/dev/null</filename>
-                its configuration will not be loaded and it appears
-                with a load state of <literal>masked</literal>, and
-                cannot be activated. Use this as an effective way to
-                fully disable a unit, making it impossible to start it
-                even manually.</para>
-
-                <para>The unit file format is covered by the
+                <para>Additional units might be loaded into systemd
+                ("linked") from directories not on the unit load
+                path. See the <command>link</command> command for
+                <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>. Also,
+                some units are dynamically created via generators
                 <ulink
-                url="http://www.freedesktop.org/wiki/Software/systemd/InterfaceStabilityPromise">Interface
-                Stability Promise</ulink>.</para>
+                url="http://www.freedesktop.org/wiki/Software/systemd/Generators/">Generators</ulink>.
+                </para>
         </refsect1>
 
         <refsect1>
                 carries generic information about the unit that is not
                 dependent on the type of unit:</para>
 
-                <variablelist>
+                <variablelist class='unit-directives'>
 
                         <varlistentry>
                                 <term><varname>Description=</varname></term>
                                 describing the unit. This is intended
                                 for use in UIs to show descriptive
                                 information along with the unit
-                                name.</para></listitem>
+                                name. The description should contain a name
+                                that means something to the end user.
+                                <literal>Apache2 Web Server</literal> is a good
+                                example. Bad examples are
+                                <literal>high-performance light-weight HTTP
+                                server</literal> (too generic) or
+                                <literal>Apache2</literal> (too specific and
+                                meaningless for people who do not know
+                                Apache).</para></listitem>
                         </varlistentry>
 
                         <varlistentry>
                                 <term><varname>Documentation=</varname></term>
-                                <listitem><para>A space separated list
+                                <listitem><para>A space-separated list
                                 of URIs referencing documentation for
                                 this unit or its
                                 configuration. Accepted are only URIs
                                 <literal>info:</literal>,
                                 <literal>man:</literal>. For more
                                 information about the syntax of these
-                                URIs see
+                                URIs, see
                                 <citerefentry><refentrytitle>uri</refentrytitle><manvolnum>7</manvolnum></citerefentry>. The
                                 URIs should be listed in order of
                                 relevance, starting with the most
                                 reference documentation that explains
                                 what the unit's purpose is, followed
                                 by how it is configured, followed by
-                                any other related
-                                documentation.</para></listitem>
+                                any other related documentation. This
+                                option may be specified more than once
+                                in which case the specified list of
+                                URIs is merged. If the empty string is
+                                assigned to this option, the list is
+                                reset and all prior assignments will
+                                have no effect.</para></listitem>
                         </varlistentry>
 
                         <varlistentry>
                                 the start-up was pulled in indirectly
                                 by some dependency or automatic
                                 start-up of units that is not
-                                requested by the user this dependency
+                                requested by the user, this dependency
                                 must be fulfilled and otherwise the
                                 transaction fails. Hence, this option
                                 may be used to configure dependencies
                                 type <varname>After=</varname> or
                                 <varname>Before=</varname>. If two
                                 units have no ordering dependencies
-                                between them they are shut down
+                                between them, they are shut down
                                 or started up simultaneously, and
                                 no ordering takes
                                 place. </para></listitem>
                                 <listitem><para>Lists one or more
                                 units that are activated when this
                                 unit enters the
-                                '<literal>failed</literal>'
+                                <literal>failed</literal>
                                 state.</para></listitem>
                         </varlistentry>
 
                         <varlistentry>
                                 <term><varname>RequiresMountsFor=</varname></term>
 
-                                <listitem><para>Takes a space
-                                separated list of absolute paths. Automatically
+                                <listitem><para>Takes a space-separated
+                                list of absolute paths. Automatically
                                 adds dependencies of type
                                 <varname>Requires=</varname> and
                                 <varname>After=</varname> for all
                                 <term><varname>OnFailureIsolate=</varname></term>
 
                                 <listitem><para>Takes a boolean
-                                argument. If <option>true</option> the
+                                argument. If <option>true</option>, the
                                 unit listed in
                                 <varname>OnFailure=</varname> will be
                                 enqueued in isolation mode, i.e. all
                                 units that are not its dependency will
-                                be stopped. If this is set only a
+                                be stopped. If this is set, only a
                                 single unit may be listed in
                                 <varname>OnFailure=</varname>. Defaults
                                 to
                                 <term><varname>IgnoreOnIsolate=</varname></term>
 
                                 <listitem><para>Takes a boolean
-                                argument. If <option>true</option>
+                                argument. If <option>true</option>,
                                 this unit will not be stopped when
                                 isolating another unit. Defaults to
                                 <option>false</option>.</para></listitem>
                                 <term><varname>IgnoreOnSnapshot=</varname></term>
 
                                 <listitem><para>Takes a boolean
-                                argument. If <option>true</option>
+                                argument. If <option>true</option>,
                                 this unit will not be included in
                                 snapshots. Defaults to
                                 <option>true</option> for device and
                                 <term><varname>StopWhenUnneeded=</varname></term>
 
                                 <listitem><para>Takes a boolean
-                                argument. If <option>true</option>
+                                argument. If <option>true</option>,
                                 this unit will be stopped when it is
                                 no longer used. Note that in order to
                                 minimize the work to be executed,
                                 <term><varname>RefuseManualStop=</varname></term>
 
                                 <listitem><para>Takes a boolean
-                                argument. If <option>true</option>
+                                argument. If <option>true</option>,
                                 this unit can only be activated
                                 or deactivated indirectly. In
-                                this case explicit start-up
+                                this case, explicit start-up
                                 or termination requested by the
                                 user is denied, however if it is
                                 started or stopped as a
                                 <term><varname>AllowIsolate=</varname></term>
 
                                 <listitem><para>Takes a boolean
-                                argument. If <option>true</option>
+                                argument. If <option>true</option>,
                                 this unit may be used with the
                                 <command>systemctl isolate</command>
-                                command. Otherwise this will be
+                                command. Otherwise, this will be
                                 refused. It probably is a good idea to
                                 leave this disabled except for target
                                 units that shall be used similar to
                                 <term><varname>DefaultDependencies=</varname></term>
 
                                 <listitem><para>Takes a boolean
-                                argument. If <option>true</option>
+                                argument. If <option>true</option>,
                                 (the default), a few default
                                 dependencies will implicitly be
                                 created for the unit. The actual
                                 highly recommended to leave this
                                 option enabled for the majority of
                                 common units. If set to
-                                <option>false</option> this option
+                                <option>false</option>, this option
                                 does not disable all implicit
                                 dependencies, just non-essential
                                 ones.</para></listitem>
                                 <listitem><para>When clients are
                                 waiting for a job of this unit to
                                 complete, time out after the specified
-                                time. If this time limit is reached
+                                time. If this time limit is reached,
                                 the job will be cancelled, the unit
                                 however will not change state or even
-                                enter the '<literal>failed</literal>'
+                                enter the <literal>failed</literal>
                                 mode. This value defaults to 0 (job
                                 timeouts disabled), except for device
                                 units. NB: this timeout is independent
                                 <term><varname>ConditionSecurity=</varname></term>
                                 <term><varname>ConditionCapability=</varname></term>
                                 <term><varname>ConditionHost=</varname></term>
+                                <term><varname>ConditionACPower=</varname></term>
                                 <term><varname>ConditionNull=</varname></term>
 
                                 <listitem><para>Before starting a unit
                                 verify that the specified condition is
-                                true. If it is not true the starting
+                                true. If it is not true, the starting
                                 of the unit will be skipped, however
                                 all ordering dependencies of it are
                                 still respected. A failing condition
                                 a file existence condition is
                                 checked before a unit is started. If
                                 the specified absolute path name does
-                                not exist the condition will
+                                not exist, the condition will
                                 fail. If the absolute path name passed
                                 to
                                 <varname>ConditionPathExists=</varname>
                                 is prefixed with an exclamation mark
-                                ('!'), the test is negated, and the unit
+                                (<literal>!</literal>), the test is negated, and the unit
                                 is only started if the path does not
                                 exist.</para>
 
                                 exclamation mark unset). The argument
                                 must either be a single word, or an
                                 assignment (i.e. two words, separated
-                                '='). In the former
+                                <literal>=</literal>). In the former
                                 case the kernel command line is
                                 searched for the word appearing as is,
                                 or as left hand side of an
                                 <varname>xen</varname>,
                                 <varname>bochs</varname>,
                                 <varname>chroot</varname>,
+                                <varname>uml</varname>,
                                 <varname>openvz</varname>,
                                 <varname>lxc</varname>,
                                 <varname>lxc-libvirt</varname>,
                                 <varname>systemd-nspawn</varname> to
                                 test against a specific
                                 implementation. If multiple
-                                virtualization technologies are nested
+                                virtualization technologies are nested,
                                 only the innermost is considered. The
                                 test may be negated by prepending an
                                 exclamation mark.</para>
                                 <para><varname>ConditionSecurity=</varname>
                                 may be used to check whether the given
                                 security module is enabled on the
-                                system.  Currently the only recognized
-                                value is <varname>selinux</varname>.
+                                system. Currently the recognized values
+                                values are <varname>selinux</varname>,
+                                <varname>apparmor</varname>,
+                                <varname>ima</varname> and
+                                <varname>smack</varname>.
                                 The test may be negated by prepending
                                 an exclamation
                                 mark.</para>
 
                                 <para><varname>ConditionHost=</varname>
                                 may be used to match against the
-                                host name or machine ID of the
-                                host. This either takes a host name
+                                hostname or machine ID of the
+                                host. This either takes a hostname
                                 string (optionally with shell style
                                 globs) which is tested against the
-                                locally set host name as returned by
+                                locally set hostname as returned by
                                 <citerefentry><refentrytitle>gethostname</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
                                 or a machine ID formatted as string
                                 (see
                                 The test may be negated by prepending
                                 an exclamation mark.</para>
 
+                                <para><varname>ConditionACPower=</varname>
+                                may be used to check whether the
+                                system has AC power, or is exclusively
+                                battery powered at the time of
+                                activation of the unit. This takes a
+                                boolean argument. If set to
+                                <varname>true</varname>, the condition
+                                will hold only if at least one AC
+                                connector of the system is connected
+                                to a power source, or if no AC
+                                connectors are known. Conversely, if
+                                set to <varname>false</varname>, the
+                                condition will hold only if there is
+                                at least one AC connector known and
+                                all AC connectors are disconnected
+                                from a power source.</para>
+
                                 <para>Finally,
                                 <varname>ConditionNull=</varname> may
                                 be used to add a constant condition
                                 check value to the unit. It takes a
                                 boolean argument. If set to
-                                <varname>false</varname> the condition
+                                <varname>false</varname>, the condition
                                 will always fail, otherwise
                                 succeed.</para>
 
                                 <para>If multiple conditions are
-                                specified the unit will be executed if
+                                specified, the unit will be executed if
                                 all of them apply (i.e. a logical AND
                                 is applied). Condition checks can be
                                 prefixed with a pipe symbol (|) in
                                 which case a condition becomes a
                                 triggering condition. If at least one
                                 triggering condition is defined for a
-                                unit then the unit will be executed if
+                                unit, then the unit will be executed if
                                 at least one of the triggering
                                 conditions apply and all of the
                                 non-triggering conditions. If you
                                 prefix an argument with the pipe
-                                symbol and an exclamation mark the
+                                symbol and an exclamation mark, the
                                 pipe symbol must be passed first, the
                                 exclamation second. Except for
                                 <varname>ConditionPathIsSymbolicLink=</varname>,
-                                all path checks follow
-                                symlinks.</para></listitem>
+                                all path checks follow symlinks. If
+                                any of these options is assigned the
+                                empty string, the list of conditions is
+                                reset completely, all previous
+                                condition settings (of any kind) will
+                                have no effect.</para></listitem>
                         </varlistentry>
 
                         <varlistentry>
                 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
                 tool during installation of a unit:</para>
 
-                <variablelist>
+                <variablelist class='unit-directives'>
                         <varlistentry>
                                 <term><varname>Alias=</varname></term>
 
                                 time,
                                 <command>systemctl enable</command>
                                 will create symlinks from these names
-                                to the unit file name.</para></listitem>
+                                to the unit filename.</para></listitem>
                         </varlistentry>
 
                         <varlistentry>
                                 <term><varname>WantedBy=</varname></term>
                                 <term><varname>RequiredBy=</varname></term>
 
-                                <listitem><para>Installs a symlink in
-                                the <filename>.wants/</filename>
-                                or <filename>.requires/</filename>
-                                subdirectory for a unit, respectively. This has the
-                                effect that when the listed unit name
-                                is activated the unit listing it is
-                                activated
-                                too. <command>WantedBy=foo.service</command>
+                                <listitem><para>A symbolic link is
+                                created in the
+                                <filename>.wants/</filename> or
+                                <filename>.requires/</filename> directory
+                                of the listed unit when this unit is
+                                activated by <command>systemctl
+                                enable</command>.  This has the effect
+                                that a dependency of type
+                                <varname>Wants=</varname> or
+                                <varname>Requires=</varname> is added
+                                from the listed unit to the current
+                                unit. The primary result is that the
+                                current unit will be started when the
+                                listed unit is started. See the
+                                description of
+                                <varname>Wants=</varname> and
+                                <varname>Requires=</varname> in the
+                                [Unit] section for details.</para>
+
+                                <para><command>WantedBy=foo.service</command>
                                 in a service
                                 <filename>bar.service</filename> is
                                 mostly equivalent to
                                 <command>Alias=foo.service.wants/bar.service</command>
-                                in the same file.</para></listitem>
+                                in the same file. In case of template
+                                units, <command>systemctl enable</command>
+                                must be called with an instance name, and
+                                this instance will be added to the
+                                <filename>.wants/</filename> or
+                                <filename>.requires/</filename> list
+                                of the listed unit.
+                                E.g. <command>WantedBy=getty.target</command>
+                                in a service
+                                <filename>getty@.service</filename>
+                                will result in <command>systemctl
+                                enable getty@tty2.service</command>
+                                creating a
+                                <filename>getty.target.wants/getty@tty2.service</filename>
+                                link to <filename>getty@.service</filename>.
+                                </para></listitem>
                         </varlistentry>
 
                         <varlistentry>
                                 <term><varname>Also=</varname></term>
 
                                 <listitem><para>Additional units to
-                                install when this unit is
-                                installed. If the user requests
-                                installation of a unit with this
-                                option configured,
+                                install/deinstall when this unit is
+                                installed/deinstalled. If the user
+                                requests installation/deinstallation
+                                of a unit with this option configured,
                                 <command>systemctl enable</command>
-                                will automatically install units
-                                listed in this option as
+                                and <command>systemctl
+                                disable</command> will automatically
+                                install/uninstall units listed in this option as
                                 well.</para></listitem>
                         </varlistentry>
                 </variablelist>
 
+                <para>The following specifiers are interpreted in the
+                Install section: %n, %N, %p, %i, %U, %u, %m, %H, %b, %v.
+                For their meaning see the next section.
+                </para>
+        </refsect1>
+
+        <refsect1>
+                <title>Specifiers</title>
+
+                <para>Many settings resolve specifiers which may be
+                used to write generic unit files referring to runtime
+                or unit parameters that are replaced when the unit
+                files are loaded. The following specifiers are
+                understood:</para>
+
+                <table>
+                  <title>Specifiers available in unit files</title>
+                  <tgroup cols='3' align='left' colsep='1' rowsep='1'>
+                    <colspec colname="spec" />
+                    <colspec colname="mean" />
+                    <colspec colname="detail" />
+                    <thead>
+                      <row>
+                        <entry>Specifier</entry>
+                        <entry>Meaning</entry>
+                        <entry>Details</entry>
+                      </row>
+                    </thead>
+                    <tbody>
+                      <row>
+                        <entry><literal>%n</literal></entry>
+                        <entry>Full unit name</entry>
+                        <entry></entry>
+                      </row>
+                      <row>
+                        <entry><literal>%N</literal></entry>
+                        <entry>Unescaped full unit name</entry>
+                        <entry></entry>
+                      </row>
+                      <row>
+                        <entry><literal>%p</literal></entry>
+                        <entry>Prefix name</entry>
+                        <entry>For instantiated units this refers to the string before the @. For non-instantiated units this refers to to the name of the unit with the type suffix removed.</entry>
+                      </row>
+                      <row>
+                        <entry><literal>%P</literal></entry>
+                        <entry>Unescaped prefix name</entry>
+                        <entry></entry>
+                      </row>
+                      <row>
+                        <entry><literal>%i</literal></entry>
+                        <entry>Instance name</entry>
+                        <entry>For instantiated units: this is the string between the <literal>@</literal> character and the suffix.</entry>
+                      </row>
+                      <row>
+                        <entry><literal>%I</literal></entry>
+                        <entry>Unescaped instance name</entry>
+                        <entry></entry>
+                      </row>
+                      <row>
+                        <entry><literal>%f</literal></entry>
+                        <entry>Unescaped filename</entry>
+                        <entry>This is either the unescaped instance name (if applicable) with <filename>/</filename> prepended (if applicable), or the prefix name similarly prepended with <filename>/</filename>.</entry>
+                      </row>
+                      <row>
+                        <entry><literal>%c</literal></entry>
+                        <entry>Control group path of the unit</entry>
+                        <entry></entry>
+                      </row>
+                      <row>
+                        <entry><literal>%r</literal></entry>
+                        <entry>Root control group path where units are placed.</entry>
+                        <entry>For system instances this usually resolves to <filename>/system</filename>, except in containers, where the path might be prefixed with the container's root control group.</entry>
+                      </row>
+                      <row>
+                        <entry><literal>%R</literal></entry>
+                        <entry>Parent directory of the control group path where units are placed.</entry>
+                        <entry>For system instances this usually resolves to <filename>/</filename>, except in containers, where this resolves to the container's root directory. This specifier is particularly useful in the <varname>ControlGroup=</varname> setting (see <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>).</entry>
+                      </row>
+                      <row>
+                        <entry><literal>%t</literal></entry>
+                        <entry>Runtime socket dir</entry>
+                        <entry>This is either <filename>/run</filename> (for the system manager) or <literal>$XDG_RUNTIME_DIR</literal> (for user managers).</entry>
+                      </row>
+                      <row>
+                        <entry><literal>%u</literal></entry>
+                        <entry>User name</entry>
+                        <entry>This is the name of the configured user of the unit, or (if none is set) the user running the systemd instance.</entry>
+                      </row>
+                      <row>
+                        <entry><literal>%U</literal></entry>
+                        <entry>User UID</entry>
+                        <entry>This is the UID of the configured user of the unit, or (if none is set) the user running the systemd instance.</entry>
+                      </row>
+                      <row>
+                        <entry><literal>%h</literal></entry>
+                        <entry>User home directory</entry>
+                        <entry>This is the home directory of the configured user of the unit, or (if none is set) the user running the systemd instance.</entry>
+                      </row>
+                      <row>
+                        <entry><literal>%s</literal></entry>
+                        <entry>User shell</entry>
+                        <entry>This is the shell of the configured user of the unit, or (if none is set) the user running the systemd instance.  If the user is <literal>root</literal> (UID equal to 0), the shell configured in account database is ignored and <filename>/bin/sh</filename> is always used.</entry>
+                      </row>
+                      <row>
+                        <entry><literal>%m</literal></entry>
+                        <entry>Machine ID</entry>
+                        <entry>The machine ID of the running system, formatted as string. See <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry> for more information.</entry>
+                      </row>
+                      <row>
+                        <entry><literal>%b</literal></entry>
+                        <entry>Boot ID</entry>
+                        <entry>The boot ID of the running system, formatted as string. See <citerefentry><refentrytitle>random</refentrytitle><manvolnum>4</manvolnum></citerefentry> for more information.</entry>
+                      </row>
+                      <row>
+                        <entry><literal>%H</literal></entry>
+                        <entry>Host name</entry>
+                        <entry>The hostname of the running system.</entry>
+                      </row>
+                      <row>
+                        <entry><literal>%v</literal></entry>
+                        <entry>Kernel release</entry>
+                        <entry>Identical to <command>uname -r</command> output.</entry>
+                      </row>
+                      <row>
+                        <entry><literal>%%</literal></entry>
+                        <entry>Escaped %</entry>
+                        <entry>Single percent sign.</entry>
+                      </row>
+                    </tbody>
+                  </tgroup>
+                </table>
         </refsect1>
 
         <refsect1>
                         <citerefentry><refentrytitle>systemd.path</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
                         <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
                         <citerefentry><refentrytitle>systemd.snapshot</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+                        <citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+                        <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
                         <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
-                        <citerefentry><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+                        <citerefentry><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
+                        <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
+                        <citerefentry><refentrytitle>uname</refentrytitle><manvolnum>1</manvolnum></citerefentry>
                 </para>
         </refsect1>