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
systemctl preset (for more information see systemctl(1)) which uses
this information to enable or disable a unit according to preset
policy. systemctl preset 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.
For more information on the preset logic please have a look at the
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
If no preset files exist, systemctl preset 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 "disable *" line. (See example 1, below.)
The preset files contain a list of directives consisting of either
the word "enable" or "disable" 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
Presets must refer to the "real" unit file, and not to any aliases.
See systemd.unit(5) for a description of unit aliasing.
Two different directives are understood: "enable" may be used to
enable units by default, "disable" to disable units by default.
If multiple lines apply to a unit name, the first matching one takes
precedence over all others.
Each preset file shall be named in the style of
<priority>-<policy-name>.preset. Files in /etc/ override files with
the same name in /usr/lib/ and /run/. Files in /run/ override files
with the same name in /usr/lib/. Packages should install their preset
files in /usr/lib/. Files in /etc/ 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.
If the administrator wants to disable a preset file supplied by the
vendor, the recommended way is to place a symlink to /dev/null in
/etc/systemd/system-preset/ bearing the same filename.
Example 1. Default off example/usr/lib/systemd/system-preset/99-default.preset:
This disables all units. Due to the filename prefix "99-", it will be
read last and hence can easily be overridden by spin or administrator
preset policy or suchlike.
Example 2. A GNOME spin example/usr/lib/systemd/system-preset/50-gnome.preset:
This enables the three mentioned units, plus all avahi-daemon
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.
Example 3. Administrator policy/etc/systemd/system-preset/00-lennart.preset:
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 "00-" it will be
read early and hence overrides all other preset policy files.
This page is part of the systemd (systemd system and service manager)
project. Information about the project can be found at
⟨http://www.freedesktop.org/wiki/Software/systemd⟩. If you have a bug
report for this manual page, see
page was obtained from the project's upstream Git repository
⟨https://github.com/systemd/systemd.git⟩ on 2017-03-13. If you dis‐
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systemd 233 SYSTEMD.PRESET(5)