man/systemd.path.xml

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   9   Copyright 2010 Lennart Poettering
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  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>PathExistsGlob=</varname></term>
 115                                 <term><varname>PathChanged=</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                                 existance 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 or is
 133                                 modified. <varname>DirectoryNotEmpty=</varname>
 134                                 may be used to watch a directory and
 135                                 activate the configured unit whenever
 136                                 it contains at least one file.</para>
 137
 138                                 <para>The arguments of these
 139                                 directives must be absolute file
 140                                 system paths.</para>
 141
 142                                 <para>Multiple directives may be
 143                                 combined, of the same and of different
 144                                 types, to watch multiple paths.</para>
 145
 146                                 <para>If a path is already existing
 147                                 (in case of
 148                                 <varname>PathExists=</varname> and
 149                                 <varname>PathExistsGlob=</varname>) or
 150                                 a directory already is not empty (in
 151                                 case of
 152                                 <varname>DirectoryNotEmpty=</varname>)
 153                                 at the time the path unit is
 154                                 activated, then the configured unit is
 155                                 immediately activated as
 156                                 well. Something similar does not apply
 157                                 to
 158                                 <varname>PathChanged=</varname>. The
 159                                 latter is not activated on simple
 160                                 writes but only if files with were
 161                                 opened for writing are closed.
 162                                 </para></listitem>
 163                         </varlistentry>
 164                         <varlistentry>
 165                                 <term><varname>Unit=</varname></term>
 166
 167                                 <listitem><para>The unit to activate
 168                                 when any of the configured paths
 169                                 changes. The argument is a unit name,
 170                                 whose suffix is not
 171                                 <filename>.path</filename>. If not
 172                                 specified, this value defaults to a
 173                                 service that has the same name as the
 174                                 path unit, except for the suffix. (See
 175                                 above.) It is recommended that the
 176                                 unit name that is activated and the
 177                                 unit name of the path unit are named
 178                                 identical, except for the
 179                                 suffix.</para></listitem>
 180                         </varlistentry>
 181                         <varlistentry>
 182                                 <term><varname>MakeDirectory=</varname></term>
 183
 184                                 <listitem><para>Takes a boolean
 185                                 argument. If true the directories to
 186                                 watch are created before
 187                                 watching. This option is ignored for
 188                                 <varname>PathExists=</varname>
 189                                 settings. Defaults to
 190                                 <option>false</option>.</para></listitem>
 191                         </varlistentry>
 192                         <varlistentry>
 193                                 <term><varname>DirectoryMode=</varname></term>
 194
 195                                 <listitem><para>If
 196                                 <varname>MakeDirectory=</varname> is
 197                                 enabled use the mode specified here to
 198                                 create the directories in
 199                                 question. Takes an access mode in
 200                                 octal notation. Defaults to
 201                                 <option>0755</option>.</para></listitem>
 202                         </varlistentry>
 203                 </variablelist>
 204         </refsect1>
 205
 206         <refsect1>
 207                   <title>See Also</title>
 208                   <para>
 209                           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 210                           <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 211                           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 212                           <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 213                           <citerefentry><refentrytitle>inotify</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 214                   </para>
 215         </refsect1>
 216
 217 </refentry>