GConf Repository

Each preference in the GConf repository is expressed as a key-value pair. A GConf preference key is an element in the repository that corresponds to an application preference. For example, the /apps/gnome-session/options/show_splash_screen preference key corresponds to the Show splash screen on login option in the Sessions preference tool. The Java Desktop System user interface does not contain all of the preference keys in the GConf repository. For example, the Panel preference tool does not contain an option that corresponds to the /apps/panel/global/tooltips_enabled key.

The repository is structured like a simple hierarchical file system. The repository contains the following:

• Directories that correspond to applications that use the GConf repository. For example, the file system contains the directory /apps/gnome-terminal.

• Subdirectories that correspond to categories of preferences. For example, the file system contains the directory /apps/gnome-terminal/global.

• Special files that list the preference keys in the directory, and contain information about the keys. For example, a file that contains information about the keys that relate to the HTTP proxy preferences is in the directory /system/http_proxy.

• A /schemas directory that contains files that describe all of the preference keys.

Preference keys typically have simple data types, such as the following:

• Strings

• Integers

• Lists of strings

• Lists of integers

The format of the preference key in the repository depends on the backend module that is used to read the repository. The following is an example of the /desktop/gnome/interface/font_name preference key when an Extensible Markup Language (XML) backend module is used to read the repository:

<entry name="font_name" mtime="1038323555" muser="user123" type="string">
<stringvalue>Sans 10</stringvalue></entry>

When this guide refers to a preference key, the path to the key is added to the name of the key. For example, the font_name preference key in the /desktop/gnome/interface subdirectory is referred to as /desktop/gnome/interface/font_name.

GConf Configuration Sources

The GConf repository contains a series of storage locations that are called configuration sources. The configuration sources are listed in the GConf path file. The location of the GConf path file is /etc/gconf/gconf-version-number/path. Each user has a path file. The path file specifies the following information for each configuration source:

• The backend module to use to read the repository.

• The permissions on the repository.

• The location of the repository.

The GConf path file also contains include instructions. By default, the contents of the GConf path file are as follows:

xml:readonly:/etc/gconf/gconf.xml.mandatory
include /etc/gconf/2/local-mandatory.path
apoc:readonly:mandatory@
include "$(HOME)/.gconf.path"
xml:readwrite:$(HOME)/.gconf
apoc:readonly:@
include /etc/gconf/2/local-defaults.path
xml:readonly:/etc/gconf/gconf.xml.defaults

When GConf searches for a preference value, GConf reads the configuration sources in the order specified in the path file. The following table describes the configuration sources in the path file:

The sequence of the configuration sources in the path file ensures that mandatory preference settings override user preference settings. The sequence also ensures that user preference settings override default preference settings. That is, GConf applies preferences in the following order of priority:

1. Mandatory preferences

2. User-specified preferences

3. Default preferences

The include instructions in the GConf path file enable system administrators to specify other configuration sources.

The apoc references in the GConf path file specify a Sun Java Desktop System Configuration Manager backend module. For more information about Sun Java Desktop System Configuration Manager, see the Sun Java Desktop System Configuration Manager documentation at http://docs.sun.com.

GConf Schemas

A GConf schema is a collective term for a GConf schema key and a GConf schema object. The following table describes schema keys and schema objects and the relationship of these items to preference keys:

The following table gives examples of a preference key, a schema key, and a schema object:

<schema>
  <applyto>/desktop/gnome/interface/font_name</applyto>
  <key>/schemas/desktop/gnome/interface/font_name</key>
  <owner>gnome</owner>
  <type>string</type>
  <default>Sans 10</default>
  <locale name="C">
    <short>Default font</short>
      <long>Name of the default font used by gtk+.</long>
  </locale>
</schema>

You can associate a schema key with a preference key. For example, the following /desktop/gnome/interface/font_name key includes a schema key:

<entry name="font_name" mtime="1034873859" 
schema="/schemas/desktop/gnome/interface/font_name"/>

When you associate a schema key with a preference key, the preference uses the suggested value that is specified in the schema object of the schema key. The suggested value is contained in the <default> element in the schema object. By default, all the preference keys in the default configuration source are associated with schema keys.

Typically, schemas are stored in the default configuration source.

GConf Schema Definition Files

Schemas are generated from schema definition files. A schema definition file defines the characteristics of all of the keys in a particular application. Schema definition files have a .schemas extension.

The schema definition files are included in the /etc/gconf/schemas directory. You can use the schema definition files to create a new configuration source.

Some schema definition files correspond closely to a part of the Java Desktop System user interface. For example, system_http_proxy.schemas corresponds to the Internet preference tool. Other schema definition files contain preference keys that are not present in the Java Desktop System user interface. For example, the /apps/panel/global/tooltips_enabled key is not present in the user interface.

Some parts of the Java Desktop System user interface contain preferences that represent preference keys from more than one schema definition file. For example, the Shortcuts preference tool contains preferences that represent keys from the panel-global-config.schemas and metacity.schemas files.