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2 <?xml-stylesheet type="text/xsl" href="http://docbook.sourceforge.net/release/xsl/current/xhtml/docbook.xsl"?>
3 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
4         "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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24
25 <refentry id="systemd.path">
26         <refentryinfo>
27                 <title>systemd.path</title>
28                 <productname>systemd</productname>
29
30                 <authorgroup>
31                         <author>
32                                 <contrib>Developer</contrib>
33                                 <firstname>Lennart</firstname>
34                                 <surname>Poettering</surname>
35                                 <email>lennart@poettering.net</email>
36                         </author>
37                 </authorgroup>
38         </refentryinfo>
39
40         <refmeta>
41                 <refentrytitle>systemd.path</refentrytitle>
42                 <manvolnum>5</manvolnum>
43         </refmeta>
44
45         <refnamediv>
46                 <refname>systemd.path</refname>
47                 <refpurpose>systemd path configuration files</refpurpose>
48         </refnamediv>
49
50         <refsynopsisdiv>
51                 <para><filename>systemd.path</filename></para>
52         </refsynopsisdiv>
53
54         <refsect1>
55                 <title>Description</title>
56
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>
61
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>
70
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>
79
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>
86
87                 <para>If an path unit is beneath another mount
88                 point in the file system hierarchy, a dependency
89                 between both units is created automatically.</para>
90
91                 <para>Unless <varname>DefaultDependencies=</varname>
92                 is set to <option>false</option>, path units will
93                 implicitly have dependencies of type
94                 <varname>Conflicts=</varname> and
95                 <varname>Before=</varname> on
96                 <filename>shutdown.target</filename>. These ensure
97                 that path units are terminated cleanly prior to system
98                 shutdown. Only path units involved with early boot or
99                 late system shutdown should disable this
100                 option.</para>
101         </refsect1>
102
103         <refsect1>
104                 <title>Options</title>
105
106                 <para>Path files must include a [Path] section,
107                 which carries information about the path(s) it
108                 monitors. The options specific to the [Path] section
109                 of path units are the following:</para>
110
111                 <variablelist>
112                         <varlistentry>
113                                 <term><varname>PathExists=</varname></term>
114                                 <term><varname>PathChanged=</varname></term>
115                                 <term><varname>DirectoryNotEmpty=</varname></term>
116
117                                 <listitem><para>Defines paths to
118                                 monitor for certain changes:
119                                 <varname>PathExists=</varname> may be
120                                 used to watch the mere existence of a
121                                 file or directory. If the file
122                                 specified exists the configured unit
123                                 is
124                                 activated. <varname>PathChanged=</varname>
125                                 may be used to watch a file or
126                                 directory and activate the configured
127                                 unit whenever it changes or is
128                                 modified. <varname>DirectoryNotEmpty=</varname>
129                                 may be used to watch a directory and
130                                 activate the configured unit whenever
131                                 it contains at least one file.</para>
132
133                                 <para>The arguments of these
134                                 directives must be absolute file
135                                 system paths.</para>
136
137                                 <para>Multiple directives may be
138                                 combined, of the same and of different
139                                 types, to watch multiple paths.</para>
140
141                                 <para>If a path is already existing
142                                 (in case of
143                                 <varname>PathExists=</varname>) or a
144                                 directory already is not empty (in
145                                 case of
146                                 <varname>DirectoryNotEmpty=</varname>)
147                                 at the time the path unit is activated,
148                                 then the configured unit is
149                                 immediately activated as
150                                 well. Something similar does not apply
151                                 to <varname>PathChanged=</varname>.
152                                 </para></listitem>
153                         </varlistentry>
154                         <varlistentry>
155                                 <term><varname>Unit=</varname></term>
156
157                                 <listitem><para>The unit to activate
158                                 when any of the configured paths
159                                 changes. The argument is a unit name,
160                                 whose suffix is not
161                                 <filename>.path</filename>. If not
162                                 specified, this value defaults to a
163                                 service that has the same name as the
164                                 path unit, except for the suffix. (See
165                                 above.) It is recommended that the
166                                 unit name that is activated and the
167                                 unit name of the path unit are named
168                                 identical, except for the
169                                 suffix.</para></listitem>
170                         </varlistentry>
171                 </variablelist>
172         </refsect1>
173
174         <refsect1>
175                   <title>See Also</title>
176                   <para>
177                           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
178                           <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
179                           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
180                           <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
181                           <citerefentry><refentrytitle>inotify</refentrytitle><manvolnum>7</manvolnum></citerefentry>
182                   </para>
183         </refsect1>
184
185 </refentry>