systemd.preset(5)

SYSTEMD.PRESET(5)               systemd.preset               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. Multiple instance names for unit templates may be specified as
       a space separated list at the end of the line instead of the customary
       position between "@" and the unit suffix.

       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.

EXAMPLES
       Example 1. Default to off

           # /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.

       Example 2. Enable multiple template instances

           # /lib/systemd/system-preset/80-dirsrv.preset

           enable dirsrv@.service foo bar baz

       This enables all three of dirsrv@foo.service, dirsrv@bar.service and
       dirsrv@baz.service.

       Example 3. A GNOME spin

           # /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 4. 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 override all other preset policy files.

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

NOTES
        1. Presets
           https://www.freedesktop.org/wiki/Software/systemd/Preset

systemd 245                                                  SYSTEMD.PRESET(5)