systemd.preset(5)

NAME

   systemd.preset - Service enablement presets

SYNOPSIS

   /etc/systemd/system-preset/*.preset

   /run/systemd/system-preset/*.preset

   /lib/systemd/system-preset/*.preset

   /etc/systemd/user-preset/*.preset

   /run/systemd/user-preset/*.preset

   /usr/lib/systemd/user-preset/*.preset

DESCRIPTION

   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
   Presets[1] document.

   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.

   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.)

PRESET FILE FORMAT

   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
   ignored.

   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 /lib/. Packages should install their preset files in
   /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

   Example 1. Default off example
   /lib/systemd/system-preset/99-default.preset:

       disable *

   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
   /lib/systemd/system-preset/50-gnome.preset:

       enable gdm.service
       enable colord.service
       enable accounts-daemon.service
       enable avahi-daemon.*

   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:

       enable httpd.service
       enable sshd.service
       enable postfix.service
       disable *

   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.

SEE ALSO

   systemd(1), systemctl(1), systemd-delta(1)

NOTES

    1. Presets
       http://freedesktop.org/wiki/Software/systemd/Preset

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