Ubuntu – How to clean up the dconf database

dconfmaintenance

Dconf is pretty young, yet my database is already a mess with lots of "schema-less" keys. Is there a way to do some cleaning up, or would I need to start from scratch (by removing ~/.config/dconf/user I guess)?

Best Answer

This is possible using the dconf reset command, though it's not clear if that's a side-effect of a bug.

For a single key:
```
dconf reset "/path/to/the/key"
```
Must not end with a /.
For a whole path:
```
dconf reset -f "/path/to/the/path/"
```
Must end with a /.

If you do this while having dconf-editor opened, it will likely crash.

Related Solutions

Ubuntu – Shouldn’t dconf-editor and gsettings access the same database

dconf-editor uses schema path to show settings data tree. Same structure used to store data in GVariant database.
gsettings (from glib-2.0) uses schema id to show/get settings data. Same way as any other application should do which uses GSetttings API.
It's up to the application developer to set both as he/she would like. (with some restriction for canonical naming). So path could be different than id but most application developers prefer to use identical word series/combination. Some don't preserve same capitalization. Example Tracker project from Gnome
```
<schema id="org.freedesktop.Tracker.Miner" path="/org/freedesktop/tracker/miner/" />
```
In addition to that, some alternative applications share same settings which belong to the Gnome desktop. Example: input-sources

First, Apps should not mess with dconf

Introduction from dconf project page:

dconf is a low-level configuration system. Its main purpose is to provide a backend to GSettings on platforms that don't already have configuration storage systems.

Where's the data stored? (Ref: https://wiki.gnome.org/Projects/dconf/SystemAdministrators)

A profile is a list of configuration databases. What it seems that Gnome & Unity use same profile.

$ cat /etc/dconf/profile/gdm
user-db:user
system-db:gdm

user-db:user: First database in the profile is read-write rw and it is created in the user's home directory.
```
$ file ~/.config/dconf/user
/home/sneetsher/.config/dconf/user: GVariant Database file, version 0
```

system-db:gdm: read-only

$ file /etc/dconf/db/gdm
/etc/dconf/db/gdm: GVariant Database file, version 0

dconf could bind a text style store in addition to GVariant Database from db.d/* folder. Example (Notice file path, so it is a part of system-db:gdm):

 $ cat /etc/dconf/db/gdm.d/00-upstream-settings

 # This file is part of the GDM packaging and should not be changed.
 #
 # Instead create your own file next to it with a higher numbered prefix,
 # and run
 #
 #       dconf update
 #

 [org/gnome/desktop/a11y/keyboard]
 enable=true

 [org/gnome/desktop/background]
 show-desktop-icons=false
 ...

Schema Files: Relation between schema id & schema path (*.gschema.xml)

What is the schema XML file in the data/glib-2.0 folder of my Quickly application? by trent shows a nice example of using GSettings API in a Quickly application, and his conclusion based on his experience.

Back to Vino. Each application that uses GSsettings should define its schema's and should store/install them in /usr/share/glib-2.0/schemas/ (It's a glib directory):

$ dpkg -L vino | grep -i glib-2.0
/usr/share/glib-2.0
/usr/share/glib-2.0/schemas
/usr/share/glib-2.0/schemas/org.gnome.Vino.enums.xml
/usr/share/glib-2.0/schemas/org.gnome.Vino.gschema.xml

$ more /usr/share/glib-2.0/schemas/org.gnome.Vino.gschema.xml
<schemalist>
  <schema id='org.gnome.Vino' path='/org/gnome/desktop/remote-access/'>
    <key name='enabled' type='b'>
      <summary>Enable remote access to the desktop</summary>
      <description>
        If true, allows remote access to the desktop via the RFB
        protocol. Users on remote machines may then connect to the
        desktop using a VNC viewer.
      </description>
      <default>false</default>
    </key>

    <key name='prompt-enabled' type='b'>
      <summary>Prompt the user before completing a connection</summary>
      <description>
        If true, remote users accessing the desktop are not allowed
        access until the user on the host machine approves the
        connection. Recommended especially when access is not password
        protected.
      </description>
      <default>true</default>
    </key>
...

If you noticed, The schema is defined with an id and a path. The schema file name follows the id value.

<schema id='org.gnome.Vino' path='/org/gnome/desktop/remote-access/'>

*.enums.xml files are for custom enumeration declaration, to be used as new data types in *.gschema.xml with same schema id.

$ cat /usr/share/glib-2.0/schemas/org.gnome.Vino.enums.xml
<!-- Generated data (by glib-mkenums) -->

<schemalist>
  <enum id='org.gnome.Vino.VinoIconVisibility'>
    <value nick='never' value='0'/>
    <value nick='always' value='1'/>
    <value nick='client' value='2'/>
  </enum>
</schemalist>

<!-- Generated data ends here -->

$ gsettings range org.gnome.Vino icon-visibility
enum
'never'
'always'
'client'

$ gsettings get org.gnome.Vino icon-visibility
'client'

Compiling Schema's (Ref: Playing with dconf and gnome-tweak-tool)

As part of the installation process (it has a dpkg trigger), schema's are compiled with glib-compile-schemas tool (from glib)
```
sudo glib-compile-schemas /usr/share/glib-2.0/schemas
```
*.gschema.xml will be compiled to a binary file /usr/share/glib-2.0/schemas/gschemas.compiled

Vendor Override Files (*.gschema.override)

In addition to schema files, glib-compile-schemas reads vendor override files, which are key files that can override default values for keys in the schemas (Ref: man glib-compile-schemas). They contain the changes done by Ubuntu distribution to override upstream schema defaults.

$ ls /usr/share/glib-2.0/schemas/*.gschema.override
/usr/share/glib-2.0/schemas/10_compiz-gnome.gschema.override
/usr/share/glib-2.0/schemas/10_desktop-base.gschema.override
/usr/share/glib-2.0/schemas/10_evolution-common.gschema.override
/usr/share/glib-2.0/schemas/10_gnome-settings-daemon.gschema.override
/usr/share/glib-2.0/schemas/10_gnome-shell.gschema.override
/usr/share/glib-2.0/schemas/10_gnome-system-log.gschema.override
/usr/share/glib-2.0/schemas/10_gsettings-desktop-schemas.gschema.override
/usr/share/glib-2.0/schemas/10_libgtk-3-common.gschema.override
/usr/share/glib-2.0/schemas/10_ubuntu-settings.gschema.override
/usr/share/glib-2.0/schemas/20_ubuntu-gnome-default-settings.gschema.override

$ cat /usr/share/glib-2.0/schemas/10_gnome-settings-daemon.gschema.override
[org.gnome.desktop.wm.keybindings]
switch-input-source=['<Super>space']
switch-input-source-backward=['<Shift><Super>space']

Example of override files use, See How to customize the Ubuntu Live CD? (5. Customization 2: Backgrounds and Themes).

Lock files

Currently, dconf supports only per-key locking, no sub-path lock. User defined values will still be stored in user-db but will have no effect on applications. dconf/gsettings returns default values instead for those locked keys. Lock files are stored in db.d/locks/. Example:

$ cat /etc/dconf/db/gdm.d/locks/00-upstream-settings-locks 
/org/gnome/desktop/a11y/keyboard/enable
/org/gnome/desktop/background/show-desktop-icons
/org/gnome/desktop/lockdown/disable-application-handlers
/org/gnome/desktop/lockdown/disable-command-line
/org/gnome/desktop/lockdown/disable-lock-screen
/org/gnome/desktop/lockdown/disable-log-out
/org/gnome/desktop/lockdown/disable-printing
/org/gnome/desktop/lockdown/disable-print-setup
/org/gnome/desktop/lockdown/disable-save-to-disk
/org/gnome/desktop/lockdown/disable-user-switching
...

After locks modification, to be effective run:

sudo dconf update

A good showcase: dconf Settings: defaults and locks

Changing Global Settings

The default for gsettings/dconf-editor is to edit the user-db. To change system-db, write a new override file and recompile schema's.

I couldn't get this to work:
```
sudo su gdm -c 'gsettings ...'
```
neither the other answers here Set Default/Global Gnome Preferences (Gnome 3), may be that was for an old release.

Ubuntu – How to dump all the manully altered dconf / gsettings keys

dconf provides such an option (Ref: man dconf)

To dump only user-altered (non-default) keys:
```
  dconf dump / > dump.dconf
```
To restore:
```
  dconf load / < dump.dconf
```

Best Answer

Related Solutions

Ubuntu – Shouldn’t dconf-editor and gsettings access the same database

Ubuntu – How to dump all the manully altered dconf / gsettings keys

Related Question