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7 This file is part of systemd.
9 Copyright 2010 Lennart Poettering
11 systemd is free software; you can redistribute it and/or modify it
12 under the terms of the GNU Lesser General Public License as published by
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25 <refentry id="systemd.path">
27 <title>systemd.path</title>
28 <productname>systemd</productname>
32 <contrib>Developer</contrib>
33 <firstname>Lennart</firstname>
34 <surname>Poettering</surname>
35 <email>lennart@poettering.net</email>
41 <refentrytitle>systemd.path</refentrytitle>
42 <manvolnum>5</manvolnum>
46 <refname>systemd.path</refname>
47 <refpurpose>Path unit configuration</refpurpose>
51 <para><filename><replaceable>path</replaceable>.path</filename></para>
55 <title>Description</title>
57 <para>A unit configuration file whose name ends in
58 <filename>.path</filename> encodes information about
59 a path monitored by systemd, for
60 path-based activation.</para>
62 <para>This man page lists the configuration options
63 specific to this unit type. See
64 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
65 for the common options of all unit configuration
66 files. The common configuration items are configured
67 in the generic [Unit] and [Install] sections. The
68 path specific configuration options are configured in
69 the [Path] section.</para>
71 <para>For each path file, a matching unit file must
72 exist, describing the unit to activate when the path
73 changes. By default, a service by the same name as the
74 path (except for the suffix) is activated. Example: a
75 path file <filename>foo.path</filename> activates a
76 matching service <filename>foo.service</filename>. The
77 unit to activate may be controlled by
78 <varname>Unit=</varname> (see below).</para>
80 <para>Internally, path units use the
81 <citerefentry><refentrytitle>inotify</refentrytitle><manvolnum>7</manvolnum></citerefentry>
82 API to monitor file systems. Due to that, it suffers by the
83 same limitations as inotify, and for example cannot be
84 used to monitor files or directories changed by other
85 machines on remote NFS file systems.</para>
87 <para>If a path unit is beneath another mount
88 point in the file system hierarchy, a dependency
89 between both units is created automatically.</para>
91 <para>Unless <varname>DefaultDependencies=false</varname>
92 is used, path units will implicitly have dependencies of
93 type <varname>Conflicts=</varname> and
94 <varname>Before=</varname> on
95 <filename>shutdown.target</filename>. These ensure
96 that path units are terminated cleanly prior to system
97 shutdown. Only path units involved with early boot or
98 late system shutdown should disable this option.
103 <title>Options</title>
105 <para>Path files must include a [Path] section,
106 which carries information about the path(s) it
107 monitors. The options specific to the [Path] section
108 of path units are the following:</para>
110 <variablelist class='unit-directives'>
112 <term><varname>PathExists=</varname></term>
113 <term><varname>PathExistsGlob=</varname></term>
114 <term><varname>PathChanged=</varname></term>
115 <term><varname>PathModified=</varname></term>
116 <term><varname>DirectoryNotEmpty=</varname></term>
118 <listitem><para>Defines paths to
119 monitor for certain changes:
120 <varname>PathExists=</varname> may be
121 used to watch the mere existence of a
122 file or directory. If the file
123 specified exists the configured unit
125 activated. <varname>PathExistsGlob=</varname>
126 works similar, but checks for the
127 existence of at least one file
128 matching the globbing pattern
129 specified. <varname>PathChanged=</varname>
130 may be used to watch a file or
131 directory and activate the configured
132 unit whenever it changes. It is not
133 activated on every write to the
134 watched file but it is activated if
135 the file which was open for writing
137 closed. <varname>PathModified=</varname>
138 is similar, but additionally it is
139 activated also on simple writes to the
141 <varname>DirectoryNotEmpty=</varname>
142 may be used to watch a directory and
143 activate the configured unit whenever
144 it contains at least one file.</para>
146 <para>The arguments of these
147 directives must be absolute file
150 <para>Multiple directives may be
151 combined, of the same and of different
152 types, to watch multiple paths. If the
153 empty string is assigned to any of
154 these options the list of paths to
155 watch is reset, and any prior
156 assignments of these options will not
157 have any effect.</para>
159 <para>If a path already exists
161 <varname>PathExists=</varname> and
162 <varname>PathExistsGlob=</varname>) or
163 a directory already is not empty (in
165 <varname>DirectoryNotEmpty=</varname>)
166 at the time the path unit is
167 activated, then the configured unit is
168 immediately activated as
169 well. Something similar does not apply
170 to <varname>PathChanged=</varname> and
171 <varname>PathModified=</varname>.</para>
173 <para>If the path itself or any of the
174 containing directories are not
175 accessible, <command>systemd</command>
176 will watch for permission changes and
177 notice that conditions are satisfied
178 when permissions allow that.
182 <term><varname>Unit=</varname></term>
184 <listitem><para>The unit to activate
185 when any of the configured paths
186 changes. The argument is a unit name,
188 <filename>.path</filename>. If not
189 specified, this value defaults to a
190 service that has the same name as the
191 path unit, except for the suffix. (See
192 above.) It is recommended that the
193 unit name that is activated and the
194 unit name of the path unit are named
195 identical, except for the
196 suffix.</para></listitem>
199 <term><varname>MakeDirectory=</varname></term>
201 <listitem><para>Takes a boolean
202 argument. If true the directories to
203 watch are created before
204 watching. This option is ignored for
205 <varname>PathExists=</varname>
206 settings. Defaults to
207 <option>false</option>.</para></listitem>
210 <term><varname>DirectoryMode=</varname></term>
213 <varname>MakeDirectory=</varname> is
214 enabled use the mode specified here to
215 create the directories in
216 question. Takes an access mode in
217 octal notation. Defaults to
218 <option>0755</option>.</para></listitem>
224 <title>See Also</title>
226 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
227 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
228 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
229 <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
230 <citerefentry><refentrytitle>inotify</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
231 <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>