trusty (5) systemd.preset.5.gz

Provided by: systemd_204-5ubuntu20.31_amd64 bug

NAME
       systemd.preset - Service enablement presets


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

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

       /usr/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.

       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>-<program>.conf. 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 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 file names with two-digit number, to simplify ordering.

       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 file name.


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

           disable *

       This disables all units. Due to the file name 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:

           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 file name 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