mirror of
https://github.com/systemd/systemd.git
synced 2024-11-01 09:21:26 +03:00
202 lines
9.2 KiB
XML
202 lines
9.2 KiB
XML
<?xml version='1.0'?> <!--*-nxml-*-->
|
|
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
|
|
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
|
|
<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
|
|
|
|
<refentry id="systemd.path">
|
|
<refentryinfo>
|
|
<title>systemd.path</title>
|
|
<productname>systemd</productname>
|
|
</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>When a service unit triggered by a path unit terminates (regardless whether it exited successfully
|
|
or failed), monitored paths are checked immediately again, and the service accordingly restarted
|
|
instantly. As protection against busy looping in this trigger/start cycle, a start rate limit is enforced
|
|
on the service unit, see <varname>StartLimitIntervalSec=</varname> and
|
|
<varname>StartLimitBurst=</varname> in
|
|
<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>. Unlike
|
|
other service failures, the error condition that the start rate limit is hit is propagated from the
|
|
service unit to the path unit and causes the path unit to fail as well, thus ending the loop.</para>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>Automatic Dependencies</title>
|
|
|
|
<refsect2>
|
|
<title>Implicit Dependencies</title>
|
|
|
|
<para>The following dependencies are implicitly added:</para>
|
|
|
|
<itemizedlist>
|
|
<listitem><para>If a path unit is beneath another mount unit in the file
|
|
system hierarchy, both a requirement and an ordering dependency
|
|
between both units are created automatically.</para></listitem>
|
|
|
|
<listitem><para>An implicit <varname>Before=</varname> dependency is added
|
|
between a path unit and the unit it is supposed to activate.</para></listitem>
|
|
</itemizedlist>
|
|
</refsect2>
|
|
|
|
<refsect2>
|
|
<title>Default Dependencies</title>
|
|
|
|
<para>The following dependencies are added unless <varname>DefaultDependencies=no</varname> is set:</para>
|
|
|
|
<itemizedlist>
|
|
<listitem><para>Path units will automatically have dependencies of type <varname>Before=</varname> on
|
|
<filename>paths.target</filename>,
|
|
dependencies of type <varname>After=</varname> and <varname>Requires=</varname> on
|
|
<filename>sysinit.target</filename>, and 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 <varname>DefaultDependencies=</varname> option.</para></listitem>
|
|
</itemizedlist>
|
|
|
|
<para></para>
|
|
</refsect2>
|
|
</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>
|