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| <!--*-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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| Copyright 2011 Lennart Poettering |
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| <refentry id="systemd.preset"> |
| |
| <refentryinfo> |
| <title>systemd.preset</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.preset</refentrytitle> |
| <manvolnum>5</manvolnum> |
| </refmeta> |
| |
| <refnamediv> |
| <refname>systemd.preset</refname> |
| <refpurpose>Service enablement presets</refpurpose> |
| </refnamediv> |
| |
| <refsynopsisdiv> |
| <para><filename>/etc/systemd/system-preset/*.preset</filename></para> |
| <para><filename>/run/systemd/system-preset/*.preset</filename></para> |
| <para><filename>/usr/lib/systemd/system-preset/*.preset</filename></para> |
| <para><filename>/etc/systemd/user-preset/*.preset</filename></para> |
| <para><filename>/run/systemd/user-preset/*.preset</filename></para> |
| <para><filename>/usr/lib/systemd/user-preset/*.preset</filename></para> |
| </refsynopsisdiv> |
| |
| <refsect1> |
| <title>Description</title> |
| |
| <para>Preset files may be used to encode policy which |
| units shall be enabled by default and which ones |
| shall be disabled. They are read by <command>systemctl |
| preset</command> (for more information see |
| <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>) |
| which uses this information to enable or disable a |
| unit according to preset policy. <command>systemctl |
| preset</command> is used by the post install |
| scriptlets of RPM packages (or other OS package formats), |
| to enable/disable specific units by default on package |
| installation, enforcing distribution, spin or |
| administrator preset policy. This allows choosing a certain |
| set of units to be enabled/disabled even before |
| installing the actual package.</para> |
| |
| <para>For more information on the preset logic please |
| have a look at the <ulink |
| url="http://freedesktop.org/wiki/Software/systemd/Preset">Presets</ulink> |
| document.</para> |
| |
| <para>It is not recommended to ship preset files |
| within the respective software packages implementing |
| the units, but rather centralize them in a |
| distribution or spin default policy, which can be |
| amended by administrator policy.</para> |
| |
| <para>If no preset files exist, <command>systemctl |
| preset</command> will enable all units that are |
| installed by default. If this is not desired and all |
| units shall rather be disabled it is necessary to ship |
| a preset file with a single, catchall |
| "<filename>disable *</filename>" line. (See example 1, |
| below.)</para> |
| </refsect1> |
| |
| <refsect1> |
| <title>Preset File Format</title> |
| |
| <para>The preset files contain a list of |
| directives consisting of either the word |
| <literal>enable</literal> or |
| <literal>disable</literal> followed by a space and a |
| unit name (possibly with shell style wildcards), |
| separated by newlines. Empty lines and lines whose |
| first non-whitespace character is # or ; are |
| ignored.</para> |
| |
| <para>Two different directives are understood: |
| <literal>enable</literal> may be used to enable units |
| by default, <literal>disable</literal> to disable |
| units by default.</para> |
| |
| <para>If multiple lines apply to a unit name, the |
| first matching one takes precedence over all |
| others.</para> |
| |
| <para>Each preset file shall be named in the style of |
| <filename><priority>-<program>.conf</filename>. |
| Files in <filename>/etc/</filename> override files |
| with the same name in <filename>/usr/lib/</filename> |
| and <filename>/run/</filename>. Files in |
| <filename>/run/</filename> override files with the |
| same name in <filename>/usr/lib/</filename>. Packages |
| should install their preset files in |
| <filename>/usr/lib/</filename>. Files in |
| <filename>/etc/</filename> are reserved for the local |
| administrator, who may use this logic to override the |
| preset files installed by vendor packages. All preset |
| files are sorted by their filename in alphabetical |
| order, regardless in which of the directories they |
| reside, to guarantee that a specific preset file takes |
| precedence over another file with an alphabetically |
| earlier name, if both files contain lines that apply |
| to the same unit names. It is recommended to prefix |
| all filenames with two-digit number, to simplify |
| ordering.</para> |
| |
| <para>If the administrator wants to disable a preset |
| file supplied by the vendor, the recommended way is to |
| place a symlink to <filename>/dev/null</filename> in |
| <filename>/etc/systemd/system-preset/</filename> |
| bearing the same filename.</para> |
| </refsect1> |
| |
| <refsect1> |
| <title>Example</title> |
| |
| <example> |
| <title>Default off example <filename>/usr/lib/systemd/system-preset/99-default.preset</filename>:</title> |
| |
| <programlisting>disable *</programlisting> |
| </example> |
| |
| <para>This disables all units. Due to the filename |
| prefix <literal>99-</literal>, it will be read last and |
| hence can easily be overridden by spin or |
| administrator preset policy or suchlike.</para> |
| |
| <example> |
| <title>A GNOME spin example <filename>/usr/lib/systemd/system-preset/50-gnome.preset</filename>:</title> |
| |
| <programlisting>enable gdm.service |
| enable colord.service |
| enable accounts-daemon.service |
| enable avahi-daemon.*</programlisting> |
| |
| </example> |
| |
| <para>This enables the three mentioned units, plus all |
| <filename>avahi-daemon</filename> regardless of which |
| unit type. A file like this could be useful for |
| inclusion in a GNOME spin of a distribution. It will |
| ensure that the units necessary for GNOME are properly |
| enabled as they are installed. It leaves all other |
| units untouched, and subject to other (later) preset |
| files, for example like the one from the first example |
| above.</para> |
| |
| <example> |
| <title>Administrator policy <filename>/etc/systemd/system-preset/00-lennart.preset</filename>:</title> |
| |
| <programlisting>enable httpd.service |
| enable sshd.service |
| enable postfix.service |
| disable *</programlisting> |
| </example> |
| |
| <para>This enables three specific services and |
| disables all others. This is useful for administrators |
| to specifically select the units to enable, and |
| disable all others. Due to the filename prefix |
| <literal>00-</literal> it will be read early and hence |
| overrides all other preset policy files.</para> |
| </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-delta</refentrytitle><manvolnum>1</manvolnum></citerefentry> |
| </para> |
| </refsect1> |
| |
| </refentry> |