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man: updates to the passive target section
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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><replaceable>path</replaceable>.path</filename></para>
52         </refsynopsisdiv>
53
54         <refsect1>
55                 <title>Description</title>
56
57                 <para>A unit configuration file whose name ends in
58                 <literal>.path</literal> 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=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.
99                 </para>
100         </refsect1>
101
102         <refsect1>
103                 <title>Options</title>
104
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>
109
110                 <variablelist class='unit-directives'>
111                         <varlistentry>
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>
117
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
124                                 is
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
136                                 gets
137                                 closed. <varname>PathModified=</varname>
138                                 is similar, but additionally it is
139                                 activated also on simple writes to the
140                                 watched file.
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>
145
146                                 <para>The arguments of these
147                                 directives must be absolute file
148                                 system paths.</para>
149
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>
158
159                                 <para>If a path already exists
160                                 (in case of
161                                 <varname>PathExists=</varname> and
162                                 <varname>PathExistsGlob=</varname>) or
163                                 a directory already is not empty (in
164                                 case of
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>
172
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.
179                                 </para></listitem>
180                         </varlistentry>
181                         <varlistentry>
182                                 <term><varname>Unit=</varname></term>
183
184                                 <listitem><para>The unit to activate
185                                 when any of the configured paths
186                                 changes. The argument is a unit name,
187                                 whose suffix is not
188                                 <literal>.path</literal>. 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>
197                         </varlistentry>
198                         <varlistentry>
199                                 <term><varname>MakeDirectory=</varname></term>
200
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>
208                         </varlistentry>
209                         <varlistentry>
210                                 <term><varname>DirectoryMode=</varname></term>
211
212                                 <listitem><para>If
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>
219                         </varlistentry>
220                 </variablelist>
221         </refsect1>
222
223         <refsect1>
224                   <title>See Also</title>
225                   <para>
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>
232                   </para>
233         </refsect1>
234
235 </refentry>