systemd.preset(5) — Linux manual page


SYSTEMD.PRESET(5)              systemd.preset              SYSTEMD.PRESET(5)

NAME         top

       systemd.preset - Service enablement presets

SYNOPSIS         top







DESCRIPTION         top

       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.)


       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 /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.

EXAMPLES         top

       Example 1. Default to off

           # /usr/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

           # /usr/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

       Example 3. A GNOME spin

           # /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 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         top

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

NOTES         top

        1. Presets

COLOPHON         top

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systemd 247                                                SYSTEMD.PRESET(5)

Pages that refer to this page: systemctl(1)30-systemd-environment-d-generator(7)systemd.directives(7)systemd.index(7)