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systemd/man/systemd.path.xml
Tom Gundersen 12b42c7667 man: revert dynamic paths for split-usr setups
This did not really work out as we had hoped. Trying to do this upstream
introduced several problems that probably makes it better suited as a
downstream patch after all. At any rate, it is not releaseable in the
current state, so we at least need to revert this before the release.

 * by adjusting the path to binaries, but not do the same thing to the
   search path we end up with inconsistent man-pages. Adjusting the search
   path too would be quite messy, and it is not at all obvious that this is
   worth the effort, but at any rate it would have to be done before we
   could ship this.

 * this means that distributed man-pages does not make sense as they depend
   on config options, and for better or worse we are still distributing
   man pages, so that is something that definitely needs sorting out before
   we could ship with this patch.

 * we have long held that split-usr is only minimally supported in order
   to boot, and something we hope will eventually go away. So before we start
   adding even more magic/effort in order to make this work nicely, we should
   probably question if it makes sense at all.
2015-06-18 19:47:44 +02:00

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<?xml version='1.0'?> <!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<refentry id="systemd.path">
<refentryinfo>
<title>systemd.path</title>
<productname>systemd</productname>
<authorgroup>
<author>
<contrib>Developer</contrib>
<firstname>Lennart</firstname>
<surname>Poettering</surname>
<email>lennart@poettering.net</email>
</author>
</authorgroup>
</refentryinfo>
<refmeta>
<refentrytitle>systemd.path</refentrytitle>
<manvolnum>5</manvolnum>
</refmeta>
<refnamediv>
<refname>systemd.path</refname>
<refpurpose>Path unit configuration</refpurpose>
</refnamediv>
<refsynopsisdiv>
<para><filename><replaceable>path</replaceable>.path</filename></para>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>A unit configuration file whose name ends in
<literal>.path</literal> encodes information about a path
monitored by systemd, for path-based activation.</para>
<para>This man page lists the configuration options specific to
this unit type. See
<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
for the common options of all unit configuration files. The common
configuration items are configured in the generic [Unit] and
[Install] sections. The path specific configuration options are
configured in the [Path] section.</para>
<para>For each path file, a matching unit file must exist,
describing the unit to activate when the path changes. By default,
a service by the same name as the path (except for the suffix) is
activated. Example: a path file <filename>foo.path</filename>
activates a matching service <filename>foo.service</filename>. The
unit to activate may be controlled by <varname>Unit=</varname>
(see below).</para>
<para>Internally, path units use the
<citerefentry project='man-pages'><refentrytitle>inotify</refentrytitle><manvolnum>7</manvolnum></citerefentry>
API to monitor file systems. Due to that, it suffers by the same
limitations as inotify, and for example cannot be used to monitor
files or directories changed by other machines on remote NFS file
systems.</para>
<para>If a path unit is beneath another mount point in the file
system hierarchy, a dependency between both units is created
automatically.</para>
<para>Unless <varname>DefaultDependencies=false</varname> is used,
path units will implicitly have dependencies of type
<varname>Conflicts=</varname> and <varname>Before=</varname> on
<filename>shutdown.target</filename>. These ensure that path units
are terminated cleanly prior to system shutdown. Only path units
involved with early boot or late system shutdown should disable
this option.
</para>
</refsect1>
<refsect1>
<title>Options</title>
<para>Path files must include a [Path] section, which carries
information about the path(s) it monitors. The options specific to
the [Path] section of path units are the following:</para>
<variablelist class='unit-directives'>
<varlistentry>
<term><varname>PathExists=</varname></term>
<term><varname>PathExistsGlob=</varname></term>
<term><varname>PathChanged=</varname></term>
<term><varname>PathModified=</varname></term>
<term><varname>DirectoryNotEmpty=</varname></term>
<listitem><para>Defines paths to monitor for certain changes:
<varname>PathExists=</varname> may be used to watch the mere
existence of a file or directory. If the file specified
exists, the configured unit is activated.
<varname>PathExistsGlob=</varname> works similar, but checks
for the existence of at least one file matching the globbing
pattern specified. <varname>PathChanged=</varname> may be used
to watch a file or directory and activate the configured unit
whenever it changes. It is not activated on every write to the
watched file but it is activated if the file which was open
for writing gets closed. <varname>PathModified=</varname> is
similar, but additionally it is activated also on simple
writes to the watched file.
<varname>DirectoryNotEmpty=</varname> may be used to watch a
directory and activate the configured unit whenever it
contains at least one file.</para>
<para>The arguments of these directives must be absolute file
system paths.</para>
<para>Multiple directives may be combined, of the same and of
different types, to watch multiple paths. If the empty string
is assigned to any of these options, the list of paths to
watch is reset, and any prior assignments of these options
will not have any effect.</para>
<para>If a path already exists (in case of
<varname>PathExists=</varname> and
<varname>PathExistsGlob=</varname>) or a directory already is
not empty (in case of <varname>DirectoryNotEmpty=</varname>)
at the time the path unit is activated, then the configured
unit is immediately activated as well. Something similar does
not apply to <varname>PathChanged=</varname> and
<varname>PathModified=</varname>.</para>
<para>If the path itself or any of the containing directories
are not accessible, <command>systemd</command> will watch for
permission changes and notice that conditions are satisfied
when permissions allow that. </para></listitem>
</varlistentry>
<varlistentry>
<term><varname>Unit=</varname></term>
<listitem><para>The unit to activate when any of the
configured paths changes. The argument is a unit name, whose
suffix is not <literal>.path</literal>. If not specified, this
value defaults to a service that has the same name as the path
unit, except for the suffix. (See above.) It is recommended
that the unit name that is activated and the unit name of the
path unit are named identical, except for the
suffix.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>MakeDirectory=</varname></term>
<listitem><para>Takes a boolean argument. If true, the
directories to watch are created before watching. This option
is ignored for <varname>PathExists=</varname> settings.
Defaults to <option>false</option>.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>DirectoryMode=</varname></term>
<listitem><para>If <varname>MakeDirectory=</varname> is
enabled, use the mode specified here to create the directories
in question. Takes an access mode in octal notation. Defaults
to <option>0755</option>.</para></listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry project='man-pages'><refentrytitle>inotify</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>