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diff --git a/man/systemd.preset.xml b/man/systemd.preset.xml new file mode 100644 index 0000000..cf807bd --- /dev/null +++ b/man/systemd.preset.xml @@ -0,0 +1,174 @@ +<?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"> +<!-- + SPDX-License-Identifier: LGPL-2.1+ +--> +<refentry id="systemd.preset"> + + <refentryinfo> + <title>systemd.preset</title> + <productname>systemd</productname> + </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="https://www.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>Presets must refer to the "real" unit file, and not to any aliases. See + <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry> + for a description of unit aliasing.</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>-<policy-name>.preset</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 lexicographic order, regardless of which of the + directories they reside in. If multiple files specify the same + unit name, the entry in the file with the lexicographically + earliest name will be applied. It is recommended to prefix all + filenames with a two-digit number and a dash, to simplify the + ordering of the files.</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>Examples</title> + + <example> + <title>Default to off</title> + + <programlisting># /usr/lib/systemd/system-preset/99-default.preset + +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.</para> + + <example> + <title>A GNOME spin</title> + + <programlisting># /usr/lib/systemd/system-preset/50-gnome.preset + +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</title> + + <programlisting># /etc/systemd/system-preset/00-lennart.preset + +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 + override 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> |