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+<?xml version='1.0'?> <!--*-nxml-*-->
+<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
+ "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
+<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
+
+<refentry id="systemd.path" xmlns:xi="http://www.w3.org/2001/XInclude">
+ <refentryinfo>
+ <title>systemd.path</title>
+ <productname>systemd</productname>
+ </refentryinfo>
+
+ <refmeta>
+ <refentrytitle>systemd.path</refentrytitle>
+ <manvolnum>5</manvolnum>
+ </refmeta>
+
+ <refnamediv>
+ <refname>systemd.path</refname>
+ <refpurpose>Path unit configuration</refpurpose>
+ </refnamediv>
+
+ <refsynopsisdiv>
+ <para><filename><replaceable>path</replaceable>.path</filename></para>
+ </refsynopsisdiv>
+
+ <refsect1>
+ <title>Description</title>
+
+ <para>A unit configuration file whose name ends in
+ <literal>.path</literal> encodes information about a path
+ monitored by systemd, for path-based activation.</para>
+
+ <para>This man page lists the configuration options specific to
+ this unit type. See
+ <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ for the common options of all unit configuration files. The common
+ configuration items are configured in the generic [Unit] and
+ [Install] sections. The path specific configuration options are
+ configured in the [Path] section.</para>
+
+ <para>For each path file, a matching unit file must exist,
+ describing the unit to activate when the path changes. By default,
+ a service by the same name as the path (except for the suffix) is
+ activated. Example: a path file <filename>foo.path</filename>
+ activates a matching service <filename>foo.service</filename>. The
+ unit to activate may be controlled by <varname>Unit=</varname>
+ (see below).</para>
+
+ <para>Internally, path units use the
+ <citerefentry project='man-pages'><refentrytitle>inotify</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+ API to monitor file systems. Due to that, it suffers by the same
+ limitations as inotify, and for example cannot be used to monitor
+ files or directories changed by other machines on remote NFS file
+ systems.</para>
+
+ <para>When a service unit triggered by a path unit terminates (regardless whether it exited successfully
+ or failed), monitored paths are checked immediately again, and the service accordingly restarted
+ instantly. As protection against busy looping in this trigger/start cycle, a start rate limit is enforced
+ on the service unit, see <varname>StartLimitIntervalSec=</varname> and
+ <varname>StartLimitBurst=</varname> in
+ <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>. Unlike
+ other service failures, the error condition that the start rate limit is hit is propagated from the
+ service unit to the path unit and causes the path unit to fail as well, thus ending the loop.</para>
+ </refsect1>
+
+ <refsect1>
+ <title>Automatic Dependencies</title>
+
+ <refsect2>
+ <title>Implicit Dependencies</title>
+
+ <para>The following dependencies are implicitly added:</para>
+
+ <itemizedlist>
+ <listitem><para>If a path unit is beneath another mount unit in the file
+ system hierarchy, both a requirement and an ordering dependency
+ between both units are created automatically.</para></listitem>
+
+ <listitem><para>An implicit <varname>Before=</varname> dependency is added
+ between a path unit and the unit it is supposed to activate.</para></listitem>
+ </itemizedlist>
+ </refsect2>
+
+ <refsect2>
+ <title>Default Dependencies</title>
+
+ <para>The following dependencies are added unless <varname>DefaultDependencies=no</varname> is set:</para>
+
+ <itemizedlist>
+ <listitem><para>Path units will automatically have dependencies of type <varname>Before=</varname> on
+ <filename>paths.target</filename>,
+ dependencies of type <varname>After=</varname> and <varname>Requires=</varname> on
+ <filename>sysinit.target</filename>, and have dependencies of type <varname>Conflicts=</varname> and
+ <varname>Before=</varname> on <filename>shutdown.target</filename>. These ensure that path units are terminated
+ cleanly prior to system shutdown. Only path units involved with early boot or late system shutdown should
+ disable <varname>DefaultDependencies=</varname> option.</para></listitem>
+ </itemizedlist>
+
+ <para></para>
+ </refsect2>
+ </refsect1>
+
+ <refsect1>
+ <title>Options</title>
+
+ <para>Path unit files may include [Unit] and [Install] sections, which are described in
+ <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
+ </para>
+
+ <para>Path unit files must include a [Path] section, which carries information about the path or paths it
+ monitors. The options specific to the [Path] section of path units are the following:</para>
+
+ <variablelist class='unit-directives'>
+ <varlistentry>
+ <term><varname>PathExists=</varname></term>
+ <term><varname>PathExistsGlob=</varname></term>
+ <term><varname>PathChanged=</varname></term>
+ <term><varname>PathModified=</varname></term>
+ <term><varname>DirectoryNotEmpty=</varname></term>
+
+ <listitem><para>Defines paths to monitor for certain changes:
+ <varname>PathExists=</varname> may be used to watch the mere
+ existence of a file or directory. If the file specified
+ exists, the configured unit is activated.
+ <varname>PathExistsGlob=</varname> works similarly, but checks
+ for the existence of at least one file matching the globbing
+ pattern specified. <varname>PathChanged=</varname> may be used
+ to watch a file or directory and activate the configured unit
+ whenever it changes. It is not activated on every write to the
+ watched file but it is activated if the file which was open
+ for writing gets closed. <varname>PathModified=</varname> is
+ similar, but additionally it is activated also on simple
+ writes to the watched file.
+ <varname>DirectoryNotEmpty=</varname> may be used to watch a
+ directory and activate the configured unit whenever it
+ contains at least one file.</para>
+
+ <para>The arguments of these directives must be absolute file
+ system paths.</para>
+
+ <para>Multiple directives may be combined, of the same and of
+ different types, to watch multiple paths. If the empty string
+ is assigned to any of these options, the list of paths to
+ watch is reset, and any prior assignments of these options
+ will not have any effect.</para>
+
+ <para>If a path already exists (in case of
+ <varname>PathExists=</varname> and
+ <varname>PathExistsGlob=</varname>) or a directory already is
+ not empty (in case of <varname>DirectoryNotEmpty=</varname>)
+ at the time the path unit is activated, then the configured
+ unit is immediately activated as well. Something similar does
+ not apply to <varname>PathChanged=</varname> and
+ <varname>PathModified=</varname>.</para>
+
+ <para>If the path itself or any of the containing directories
+ are not accessible, <command>systemd</command> will watch for
+ permission changes and notice that conditions are satisfied
+ when permissions allow that. </para></listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><varname>Unit=</varname></term>
+
+ <listitem><para>The unit to activate when any of the
+ configured paths changes. The argument is a unit name, whose
+ suffix is not <literal>.path</literal>. If not specified, this
+ value defaults to a service that has the same name as the path
+ unit, except for the suffix. (See above.) It is recommended
+ that the unit name that is activated and the unit name of the
+ path unit are named identical, except for the
+ suffix.</para></listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><varname>MakeDirectory=</varname></term>
+
+ <listitem><para>Takes a boolean argument. If true, the
+ directories to watch are created before watching. This option
+ is ignored for <varname>PathExists=</varname> settings.
+ Defaults to <option>false</option>.</para></listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><varname>DirectoryMode=</varname></term>
+
+ <listitem><para>If <varname>MakeDirectory=</varname> is
+ enabled, use the mode specified here to create the directories
+ in question. Takes an access mode in octal notation. Defaults
+ to <option>0755</option>.</para></listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><varname>TriggerLimitIntervalSec=</varname></term>
+ <term><varname>TriggerLimitBurst=</varname></term>
+
+ <listitem><para>Configures a limit on how often this path unit may be activated within a specific
+ time interval. The <varname>TriggerLimitIntervalSec=</varname> may be used to configure the length of
+ the time interval in the usual time units <literal>us</literal>, <literal>ms</literal>,
+ <literal>s</literal>, <literal>min</literal>, <literal>h</literal>, … and defaults to 2s. See
+ <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry> for
+ details on the various time units understood. The <varname>TriggerLimitBurst=</varname> setting takes
+ a positive integer value and specifies the number of permitted activations per time interval, and
+ defaults to 200. Set either to 0 to disable any form of trigger rate limiting. If the limit is hit,
+ the unit is placed into a failure mode, and will not watch the paths anymore until restarted. Note
+ that this limit is enforced before the service activation is enqueued.</para></listitem>
+ </varlistentry>
+ </variablelist>
+
+ <xi:include href="systemd.service.xml" xpointer="shared-unit-options" />
+ </refsect1>
+
+ <refsect1>
+ <title>See Also</title>
+ <para>Environment variables with details on the trigger will be set for triggered units. See the
+ <literal>Environment Variables Set on Triggered Units</literal> section in
+ <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+ for more details.</para>
+ <para>
+ <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+ <citerefentry project='man-pages'><refentrytitle>inotify</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+ </para>
+ </refsect1>
+
+</refentry>