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build-sys: make PolicyKit support compile-time optional (was runtime-optional already)
[elogind.git] / man / systemd.path.xml
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3 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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9   Copyright 2010 Lennart Poettering
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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>Path unit configuration</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 a 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 class='unit-directives'>
112                         <varlistentry>
113                                 <term><varname>PathExists=</varname></term>
114                                 <term><varname>PathExistsGlob=</varname></term>
115                                 <term><varname>PathChanged=</varname></term>
116                                 <term><varname>PathModified=</varname></term>
117                                 <term><varname>DirectoryNotEmpty=</varname></term>
118
119                                 <listitem><para>Defines paths to
120                                 monitor for certain changes:
121                                 <varname>PathExists=</varname> may be
122                                 used to watch the mere existence of a
123                                 file or directory. If the file
124                                 specified exists the configured unit
125                                 is
126                                 activated. <varname>PathExistsGlob=</varname>
127                                 works similar, but checks for the
128                                 existence of at least one file
129                                 matching the globbing pattern
130                                 specified. <varname>PathChanged=</varname>
131                                 may be used to watch a file or
132                                 directory and activate the configured
133                                 unit whenever it changes. It is not
134                                 activated on every write to the
135                                 watched file but it is activated if
136                                 the file which was open for writing
137                                 gets
138                                 closed. <varname>PathModified=</varname>
139                                 is similar, but additionally it is
140                                 activated also on simple writes to the
141                                 watched file.
142                                 <varname>DirectoryNotEmpty=</varname>
143                                 may be used to watch a directory and
144                                 activate the configured unit whenever
145                                 it contains at least one file.</para>
146
147                                 <para>The arguments of these
148                                 directives must be absolute file
149                                 system paths.</para>
150
151                                 <para>Multiple directives may be
152                                 combined, of the same and of different
153                                 types, to watch multiple paths. If the
154                                 empty string is assigned to any of
155                                 these options the list of paths to
156                                 watch is reset, and any prior
157                                 assignments of these options will not
158                                 have any effect.</para>
159
160                                 <para>If a path is already existing
161                                 (in case of
162                                 <varname>PathExists=</varname> and
163                                 <varname>PathExistsGlob=</varname>) or
164                                 a directory already is not empty (in
165                                 case of
166                                 <varname>DirectoryNotEmpty=</varname>)
167                                 at the time the path unit is
168                                 activated, then the configured unit is
169                                 immediately activated as
170                                 well. Something similar does not apply
171                                 to <varname>PathChanged=</varname>.
172                                 </para></listitem>
173                         </varlistentry>
174                         <varlistentry>
175                                 <term><varname>Unit=</varname></term>
176
177                                 <listitem><para>The unit to activate
178                                 when any of the configured paths
179                                 changes. The argument is a unit name,
180                                 whose suffix is not
181                                 <filename>.path</filename>. If not
182                                 specified, this value defaults to a
183                                 service that has the same name as the
184                                 path unit, except for the suffix. (See
185                                 above.) It is recommended that the
186                                 unit name that is activated and the
187                                 unit name of the path unit are named
188                                 identical, except for the
189                                 suffix.</para></listitem>
190                         </varlistentry>
191                         <varlistentry>
192                                 <term><varname>MakeDirectory=</varname></term>
193
194                                 <listitem><para>Takes a boolean
195                                 argument. If true the directories to
196                                 watch are created before
197                                 watching. This option is ignored for
198                                 <varname>PathExists=</varname>
199                                 settings. Defaults to
200                                 <option>false</option>.</para></listitem>
201                         </varlistentry>
202                         <varlistentry>
203                                 <term><varname>DirectoryMode=</varname></term>
204
205                                 <listitem><para>If
206                                 <varname>MakeDirectory=</varname> is
207                                 enabled use the mode specified here to
208                                 create the directories in
209                                 question. Takes an access mode in
210                                 octal notation. Defaults to
211                                 <option>0755</option>.</para></listitem>
212                         </varlistentry>
213                 </variablelist>
214         </refsect1>
215
216         <refsect1>
217                   <title>See Also</title>
218                   <para>
219                           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
220                           <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
221                           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
222                           <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
223                           <citerefentry><refentrytitle>inotify</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
224                           <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>
225                   </para>
226         </refsect1>
227
228 </refentry>