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For all units ensure there's an "Automatic Dependencies" section in the man page, and explain which dependencies are automatically added in all cases, and which ones are added on top if DefaultDependencies=yes is set. This is also done for systemd.exec(5), systemd.resource-control(5) and systemd.unit(5) as these pages describe common behaviour of various unit types.
207 lines
8.8 KiB
XML
207 lines
8.8 KiB
XML
<?xml version='1.0'?> <!--*-nxml-*-->
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<!--
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This file is part of systemd.
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Copyright 2010 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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-->
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<refentry id="systemd.path">
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<refentryinfo>
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<title>systemd.path</title>
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<productname>systemd</productname>
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<authorgroup>
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<author>
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<contrib>Developer</contrib>
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<firstname>Lennart</firstname>
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<surname>Poettering</surname>
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<email>lennart@poettering.net</email>
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</author>
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</authorgroup>
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</refentryinfo>
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<refmeta>
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<refentrytitle>systemd.path</refentrytitle>
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<manvolnum>5</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>systemd.path</refname>
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<refpurpose>Path unit configuration</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<para><filename><replaceable>path</replaceable>.path</filename></para>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para>A unit configuration file whose name ends in
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<literal>.path</literal> encodes information about a path
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monitored by systemd, for path-based activation.</para>
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<para>This man page lists the configuration options specific to
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this unit type. See
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<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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for the common options of all unit configuration files. The common
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configuration items are configured in the generic [Unit] and
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[Install] sections. The path specific configuration options are
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configured in the [Path] section.</para>
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<para>For each path file, a matching unit file must exist,
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describing the unit to activate when the path changes. By default,
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a service by the same name as the path (except for the suffix) is
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activated. Example: a path file <filename>foo.path</filename>
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activates a matching service <filename>foo.service</filename>. The
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unit to activate may be controlled by <varname>Unit=</varname>
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(see below).</para>
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<para>Internally, path units use the
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<citerefentry project='man-pages'><refentrytitle>inotify</refentrytitle><manvolnum>7</manvolnum></citerefentry>
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API to monitor file systems. Due to that, it suffers by the same
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limitations as inotify, and for example cannot be used to monitor
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files or directories changed by other machines on remote NFS file
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systems.</para>
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</refsect1>
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<refsect1>
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<title>Automatic Dependencies</title>
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<para>If a path unit is beneath another mount unit in the file
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system hierarchy, both a requirement and an ordering dependency
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between both units are created automatically.</para>
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<para>An implicit <varname>Before=</varname> dependency is added
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between a path unit and the unit it is supposed to activate.</para>
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<para>Unless <varname>DefaultDependencies=false</varname> is used,
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path units will implicitly have dependencies of type
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<varname>Before=</varname> on <filename>paths.target</filename>,
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dependencies of type <varname>After=</varname> and
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<varname>Requires=</varname> on
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<filename>sysinit.target</filename>, and have dependencies of type
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<varname>Conflicts=</varname> and <varname>Before=</varname> on
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<filename>shutdown.target</filename>. These ensure that path units
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are terminated cleanly prior to system shutdown. Only path units
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involved with early boot or late system shutdown should disable
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this option.
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</para>
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</refsect1>
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<refsect1>
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<title>Options</title>
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<para>Path files must include a [Path] section, which carries
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information about the path(s) it monitors. The options specific to
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the [Path] section of path units are the following:</para>
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<variablelist class='unit-directives'>
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<varlistentry>
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<term><varname>PathExists=</varname></term>
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<term><varname>PathExistsGlob=</varname></term>
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<term><varname>PathChanged=</varname></term>
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<term><varname>PathModified=</varname></term>
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<term><varname>DirectoryNotEmpty=</varname></term>
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<listitem><para>Defines paths to monitor for certain changes:
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<varname>PathExists=</varname> may be used to watch the mere
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existence of a file or directory. If the file specified
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exists, the configured unit is activated.
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<varname>PathExistsGlob=</varname> works similar, but checks
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for the existence of at least one file matching the globbing
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pattern specified. <varname>PathChanged=</varname> may be used
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to watch a file or directory and activate the configured unit
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whenever it changes. It is not activated on every write to the
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watched file but it is activated if the file which was open
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for writing gets closed. <varname>PathModified=</varname> is
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similar, but additionally it is activated also on simple
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writes to the watched file.
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<varname>DirectoryNotEmpty=</varname> may be used to watch a
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directory and activate the configured unit whenever it
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contains at least one file.</para>
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<para>The arguments of these directives must be absolute file
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system paths.</para>
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<para>Multiple directives may be combined, of the same and of
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different types, to watch multiple paths. If the empty string
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is assigned to any of these options, the list of paths to
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watch is reset, and any prior assignments of these options
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will not have any effect.</para>
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<para>If a path already exists (in case of
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<varname>PathExists=</varname> and
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<varname>PathExistsGlob=</varname>) or a directory already is
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not empty (in case of <varname>DirectoryNotEmpty=</varname>)
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at the time the path unit is activated, then the configured
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unit is immediately activated as well. Something similar does
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not apply to <varname>PathChanged=</varname> and
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<varname>PathModified=</varname>.</para>
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<para>If the path itself or any of the containing directories
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are not accessible, <command>systemd</command> will watch for
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permission changes and notice that conditions are satisfied
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when permissions allow that. </para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>Unit=</varname></term>
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<listitem><para>The unit to activate when any of the
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configured paths changes. The argument is a unit name, whose
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suffix is not <literal>.path</literal>. If not specified, this
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value defaults to a service that has the same name as the path
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unit, except for the suffix. (See above.) It is recommended
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that the unit name that is activated and the unit name of the
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path unit are named identical, except for the
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suffix.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>MakeDirectory=</varname></term>
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<listitem><para>Takes a boolean argument. If true, the
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directories to watch are created before watching. This option
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is ignored for <varname>PathExists=</varname> settings.
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Defaults to <option>false</option>.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>DirectoryMode=</varname></term>
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<listitem><para>If <varname>MakeDirectory=</varname> is
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enabled, use the mode specified here to create the directories
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in question. Takes an access mode in octal notation. Defaults
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to <option>0755</option>.</para></listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<para>
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<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry project='man-pages'><refentrytitle>inotify</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>
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</para>
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</refsect1>
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</refentry>
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