man/systemd.path.xml

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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>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         </refsect1>
  91
  92         <refsect1>
  93                 <title>Options</title>
  94
  95                 <para>Path files must include a [Path] section,
  96                 which carries information about the path(s) it
  97                 monitors. The options specific to the [Path] section
  98                 of path units are the following:</para>
  99
 100                 <variablelist>
 101                         <varlistentry>
 102                                 <term><varname>PathExists=</varname></term>
 103                                 <term><varname>PathChanged=</varname></term>
 104                                 <term><varname>DirectoryNotEmpty=</varname></term>
 105
 106                                 <listitem><para>Defines paths to
 107                                 monitor for certain changes:
 108                                 <varname>PathExists=</varname> may be
 109                                 used to watch the mere existence of a
 110                                 file or directory. If the file
 111                                 specified exists the configured unit
 112                                 is
 113                                 activated. <varname>PathChanged=</varname>
 114                                 may be used to watch a file or
 115                                 directory and activate the configured
 116                                 unit whenever it changes or is
 117                                 modified. <varname>DirectoryNotEmpty=</varname>
 118                                 may be used to watch a directory and
 119                                 activate the configured unit whenever
 120                                 it contains at least one file.</para>
 121
 122                                 <para>The arguments of these
 123                                 directives must be absolute file
 124                                 system paths.</para>
 125
 126                                 <para>Multiple directives may be
 127                                 combined, of the same and of different
 128                                 types, to watch multiple paths.</para>
 129
 130                                 <para>If a path is already existing
 131                                 (in case of
 132                                 <varname>PathExists=</varname>) or a
 133                                 directory already is not empty (in
 134                                 case of
 135                                 <varname>DirectoryNotEmpty=</varname>)
 136                                 at the time the path unit is activated,
 137                                 then the configured unit is
 138                                 immediately activated as
 139                                 well. Something similar does not apply
 140                                 to <varname>PathChanged=</varname>.
 141                                 </para></listitem>
 142                         </varlistentry>
 143                         <varlistentry>
 144                                 <term><varname>Unit=</varname></term>
 145
 146                                 <listitem><para>The unit to activate
 147                                 when any of the configured paths
 148                                 changes. The argument is a unit name,
 149                                 whose suffix is not
 150                                 <filename>.path</filename>. If not
 151                                 specified, this value defaults to a
 152                                 service that has the same name as the
 153                                 path unit, except for the suffix. (See
 154                                 above.) It is recommended that the
 155                                 unit name that is activated and the
 156                                 unit name of the path unit are named
 157                                 identical, except for the
 158                                 suffix.</para></listitem>
 159                         </varlistentry>
 160                 </variablelist>
 161         </refsect1>
 162
 163         <refsect1>
 164                   <title>See Also</title>
 165                   <para>
 166                           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 167                           <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 168                           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 169                           <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 170                           <citerefentry><refentrytitle>inotify</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 171                   </para>
 172         </refsect1>
 173
 174 </refentry>