man/systemd.preset.html

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  22   <a href="../libudev/index.html">gudev </a><span style="float:right">systemd 219</span><hr><div class="refentry"><a name="systemd.preset"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>systemd.preset — Service enablement presets</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><p><code class="filename">/etc/systemd/system-preset/*.preset</code></p><p><code class="filename">/run/systemd/system-preset/*.preset</code></p><p><code class="filename">/usr/lib/systemd/system-preset/*.preset</code></p><p><code class="filename">/etc/systemd/user-preset/*.preset</code></p><p><code class="filename">/run/systemd/user-preset/*.preset</code></p><p><code class="filename">/usr/lib/systemd/user-preset/*.preset</code></p></div><div class="refsect1"><a name="idm140239730136768"></a><h2 id="Description">Description<a class="headerlink" title="Permalink to this headline" href="#Description">¶</a></h2><p>Preset files may be used to encode policy which units shall
  23     be enabled by default and which ones shall be disabled. They are
  24     read by <span class="command"><strong>systemctl preset</strong></span> (for more information
  25     see
  26     <a href="systemctl.html"><span class="citerefentry"><span class="refentrytitle">systemctl</span>(1)</span></a>)
  27     which uses this information to enable or disable a unit according
  28     to preset policy. <span class="command"><strong>systemctl preset</strong></span> is used by
  29     the post install scriptlets of RPM packages (or other OS package
  30     formats), to enable/disable specific units by default on package
  31     installation, enforcing distribution, spin or administrator preset
  32     policy. This allows choosing a certain set of units to be
  33     enabled/disabled even before installing the actual package.</p><p>For more information on the preset logic please have a look
  34     at the <a class="ulink" href="http://freedesktop.org/wiki/Software/systemd/Preset" target="_top">Presets</a>
  35     document.</p><p>It is not recommended to ship preset files within the
  36     respective software packages implementing the units, but rather
  37     centralize them in a distribution or spin default policy, which
  38     can be amended by administrator policy.</p><p>If no preset files exist, <span class="command"><strong>systemctl
  39     preset</strong></span> will enable all units that are installed by
  40     default. If this is not desired and all units shall rather be
  41     disabled, it is necessary to ship a preset file with a single,
  42     catchall "<code class="filename">disable *</code>" line. (See example 1,
  43     below.)</p></div><div class="refsect1"><a name="idm140239730128896"></a><h2 id="Preset File Format">Preset File Format<a class="headerlink" title="Permalink to this headline" href="#Preset%20File%20Format">¶</a></h2><p>The preset files contain a list of directives consisting of
  44     either the word "<code class="literal">enable</code>" or
  45     "<code class="literal">disable</code>" followed by a space and a unit name
  46     (possibly with shell style wildcards), separated by newlines.
  47     Empty lines and lines whose first non-whitespace character is # or
  48     ; are ignored.</p><p>Two different directives are understood:
  49     "<code class="literal">enable</code>" may be used to enable units by default,
  50     "<code class="literal">disable</code>" to disable units by default.</p><p>If multiple lines apply to a unit name, the first matching
  51     one takes precedence over all others.</p><p>Each preset file shall be named in the style of
  52     <code class="filename">&lt;priority&gt;-&lt;program&gt;.conf</code>. Files
  53     in <code class="filename">/etc/</code> override files with the same name in
  54     <code class="filename">/usr/lib/</code> and <code class="filename">/run/</code>.
  55     Files in <code class="filename">/run/</code> override files with the same
  56     name in <code class="filename">/usr/lib/</code>. Packages should install
  57     their preset files in <code class="filename">/usr/lib/</code>. Files in
  58     <code class="filename">/etc/</code> are reserved for the local
  59     administrator, who may use this logic to override the preset files
  60     installed by vendor packages. All preset files are sorted by their
  61     filename in lexicographic order, regardless of which of the
  62     directories they reside in. If multiple files specify the same
  63     unit name, the entry in the file with the lexicographically
  64     earliest name will be applied. It is recommended to prefix all
  65     filenames with a two-digit number and a dash, to simplify the
  66     ordering of the files.</p><p>If the administrator wants to disable a preset file supplied
  67     by the vendor, the recommended way is to place a symlink to
  68     <code class="filename">/dev/null</code> in
  69     <code class="filename">/etc/systemd/system-preset/</code> bearing the same
  70     filename.</p></div><div class="refsect1"><a name="idm140239734014272"></a><h2 id="Example">Example<a class="headerlink" title="Permalink to this headline" href="#Example">¶</a></h2><div class="example"><a name="idm140239734013600"></a><p class="title"><b>Example 1. Default off example <code class="filename">/usr/lib/systemd/system-preset/99-default.preset</code>:</b></p><div class="example-contents"><pre class="programlisting">disable *</pre></div></div><br class="example-break"><p>This disables all units. Due to the filename prefix
  71     "<code class="literal">99-</code>", it will be read last and hence can easily
  72     be overridden by spin or administrator preset policy or
  73     suchlike.</p><div class="example"><a name="idm140239734010192"></a><p class="title"><b>Example 2. A GNOME spin example <code class="filename">/usr/lib/systemd/system-preset/50-gnome.preset</code>:</b></p><div class="example-contents"><pre class="programlisting">enable gdm.service
  74 enable colord.service
  75 enable accounts-daemon.service
  76 enable avahi-daemon.*</pre></div></div><br class="example-break"><p>This enables the three mentioned units, plus all
  77     <code class="filename">avahi-daemon</code> regardless of which unit type. A
  78     file like this could be useful for inclusion in a GNOME spin of a
  79     distribution. It will ensure that the units necessary for GNOME
  80     are properly enabled as they are installed. It leaves all other
  81     units untouched, and subject to other (later) preset files, for
  82     example like the one from the first example above.</p><div class="example"><a name="idm140239733999184"></a><p class="title"><b>Example 3. Administrator policy <code class="filename">/etc/systemd/system-preset/00-lennart.preset</code>:</b></p><div class="example-contents"><pre class="programlisting">enable httpd.service
  83 enable sshd.service
  84 enable postfix.service
  85 disable *</pre></div></div><br class="example-break"><p>This enables three specific services and disables all
  86     others. This is useful for administrators to specifically select
  87     the units to enable, and disable all others. Due to the filename
  88     prefix "<code class="literal">00-</code>" it will be read early and hence
  89     overrides all other preset policy files.</p></div><div class="refsect1"><a name="idm140239733995680"></a><h2 id="See Also">See Also<a class="headerlink" title="Permalink to this headline" href="#See%20Also">¶</a></h2><p>
  90       <a href="systemd.html"><span class="citerefentry"><span class="refentrytitle">systemd</span>(1)</span></a>,
  91       <a href="systemctl.html"><span class="citerefentry"><span class="refentrytitle">systemctl</span>(1)</span></a>,
  92       <a href="systemd-delta.html"><span class="citerefentry"><span class="refentrytitle">systemd-delta</span>(1)</span></a>
  93     </p></div></div></body></html>