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diff --git a/man/systemd.path.xml b/man/systemd.path.xml new file mode 100644 index 0000000..f8748bf --- /dev/null +++ b/man/systemd.path.xml @@ -0,0 +1,225 @@ +<?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> |