KDE System Administration/Configuration Files: Difference between revisions

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    == File Format ==
    KDE uses a simple text-based file format for all its configuration files.
    It consists of key-value pairs that are placed in groups. All KDE
    configuration files use UTF-8 encoding for text outside the ASCII range.
     
    The start of a group is indicated by a group name that is placed in
    square brackets. All the key-value entries that follow belong to the group.
    The group ends when either another group starts or when the end of the file
    is reached.
     
    Entries at the top of the file that are not preceded by a group name belong
    to the default group.
     
    ==== Example: A Simple Config File ====
    The following example shows a configuration file that consists of two groups.
    The first group contains the keys "<tt>LargeCursor</tt>" and
    "<tt>SingleClick</tt>", the second group contains the keys
    "<tt>Show hidden files</tt>" and "<tt>Sort by</tt>".
    <syntaxhighlight lang="ini">
    [KDE]
    LargeCursor=false
    SingleClick=true
     
    [KFileDialog Settings]
    Show hidden files=false
    Sort by=Name
    </syntaxhighlight>
     
    Entries in a group consists of a key and value separated by an equal sign.
    The key can contain spaces and may be followed by options placed in
    square brackets.
     
    The part after the equal sign is the value of the entry. Any white space
    surrounding the equal sign is ignored, as is any trailing white space.
     
    If a value is supposed to include a space at the begin or end then this can be achieved
    by using a backslash followed by an 's'.
     
    There are several other backslash codes, here is the complete list:
     
    * "<tt>\s</tt>" can be used as space
    * "<tt>\t</tt>" can be used to include a tab
    * "<tt>\r</tt>" for a carriage return character
    * "<tt>\n</tt>" for a linefeed character (new line)
    * "<tt>\\</tt>" to include the backslash itself
     
    ==== Example: Whitespace ====
    The following config file fragment is equivalent to the one in the
    previous example. Whitespace surrounding the key and value is ignored.
    <syntaxhighlight lang="ini">
    [KDE]
    LargeCursor=          false
    SingleClick = true
     
    [KFileDialog Settings]
      Show hidden files  = false
    Sort by =Name
    </syntaxhighlight>
     
    ==== Example: Preserving Whitespace ====
    In the following example the value of the "<tt>Caption</tt>" entry starts
    with two spaces while the "<tt>Description</tt>" entry contains three lines
    of text. Linefeeds in backslash notation are used to separate the different lines.
    <syntaxhighlight lang="ini">
    [Preview Image]
    Caption=\s My Caption
    Description=This is\na very long\ndescription.
    </syntaxhighlight>
     
    Empty lines in configuration files are ignored, just as lines that
    start with a hash mark '#'. The hash mark can be used to add comments to
    configuration files but it should be noted that when a KDE application
    updates a configuration file the comments are not
    preserved.
     
    == Configuration ==
    There can be multiple configuration files with the same name in the
    share/config sub-directory of the various
    [[../KDE Filesystem Hierarchy#Location_of_the_Directory_Trees|KDE Directory Trees]].
    In that case the information of all these configuration files is combined
    on a key-by-key basis. If the same key within a certain group is defined
    in more than one place, the key value read from the directory tree with
    the highest precedence will be used.
    Configuration files under $KDEHOME always have the highest precedence.
    If a key in a certain group is defined multiple times in a single file, the
    value of the last entry is used.
     
    KDE's cascading configuration scheme can be used to provide users with
    system or organisation-wide default settings while still allowing the users
    to make individual changes to these settings. KDE will not write entries to
    the user's configuration file under $KDEHOME that match any default settings
    provided this way. This way changes made to the default settings will
    immediately be propagated to the user. Note that differs from the traditional
    way of providing default settings for users through the use of {{path|/etc/skel}},
    changes to {{path|/etc/skel}} will only be propagated when creating a new user account.
     
    When it is undesirable that individual users can make changes to default
    settings, the default setting can be locked down.
     
    == Shell Expansion ==
     
    So called ''Shell Expansion'' can be used to provide more dynamic default
    values. With shell expansion the value of a configuration key can be
    constructed from the value of an environment variable or from the output of
    a shell command.
     
    To enable shell expansion for a configuration entry, the key must be followed
    by <tt>[$e]</tt>. Normally the expanded form is written into the users
    configuration file after first use. To prevent that, it is recommend to lock
    the configuration entry down by using <tt>[$ie]</tt>.
     
    ==== Example: Dynamic Entries ====
    In the following example the value for the "<tt>Host</tt>" entry
    is determined by the output of the ''hostname'' program. This setting is
    also locked down to ensure that the value is always determined dynamically.
     
    The value for the "<tt>Email</tt>" entry is determined by filling in
    the values of the $USER and $HOST environment variables. When ''joe''
    is logged in on ''joes_host'' this will result in a value equal to
    "<tt>joe@joes_host</tt>". The setting is not locked down.
     
    <syntaxhighlight lang="ini">
    [Mail Settings]
    Host[$ie]=$(hostname)
    Email[$e]=${USER}@${HOST}
    </syntaxhighlight>
     
    == Localization ==
     
    All configuration entries can be indexed with a language code. In this case,
    the language that the user has selected for use on the desktop is used to
    look up the key value. If the default language (American English) has been
    selected or if there is no index that corresponds to the selected language,
    the key entry without index is used.
     
    ==== Example: UTF-8 In Keys ====
    In the following example the value of the "<tt>Caption</tt>" entry
    depends on the language. If the user has selected french as language (language
    code <tt>fr</tt>) the value of the entry will be "<tt>Ma Légende</tt>".
    In all other cases the value "<tt>My Caption</tt>" will be used.
    <syntaxhighlight lang="ini">
    [Preview Image]
    Caption=My Caption
    Caption[fr]=Ma Légende
    </syntaxhighlight>
     
    == Lock Down ==
     
    To prevent users from overriding default settings, you can lock
    these settings down in the system-wide config files. Settings can be locked down individually, per group,
    or per file. An individual entry can be locked down by adding <tt>[$i]</tt>
    behind the key. A group of entries can be locked down by placing
    <tt>[$i]</tt> behind the group name. To lock down the entire file, start
    the file with <tt>[$i]</tt> on a single line.
     
    ==== Example: Using [$i] ====
    In the following example the "<tt>Caption</tt>" entry has been locked
    down. All entries in the "<tt>Mail Settings</tt>" group have been
    locked down as well.
    <syntaxhighlight lang="text">
    [Preview Image]
    Caption[$i]=My Caption
     
    [Mail Settings][$i]
    Host[$e]=$(hostname)
    Email=wal&#100;o&#x40;&#00107;&#x64;e&#x2e;or&#x67;
    </syntaxhighlight>
     
    If an entry has been locked down, entries that would otherwise take
    precedence over the default setting will now be ignored.
     
    Any changes that applications make to settings that have been locked
    down will be silently dropped. Applications may respond differently to locked down settings. Some applications
    recognize when a setting has been locked down and will remove the
    elements from its user interface. Other applications will continue
    to offer these options in their user interface even though the option
    does not have any effect any more. It is also possible that it is actually
    still possible to change the setting in the running program. In that case the
    changed setting will be effective for the time the program remains running.
    When the program is restarted it will then return to the locked-down default
    settings.
     
    == Editors ==
    If you do not want to use a text editor then
    [http://extragear.kde.org/apps/kconfigeditor/ KConfigEditor]
    offers a convenient way to edit KDE configuration files.
     
    For scripts or modifying files from the command line, the command line app <tt>kwriteconfig</tt> is very useful. <tt>kwriteconfig</tt> expects a configuration file name, a group, a key, an optional type and a value, such as:
     
    <syntaxhighlight lang="text">kwriteconfig --file kickerrc \
                --group General \
                --key AutoHidePanel \
                --type bool \
                true</syntaxhighlight>

    Latest revision as of 13:19, 11 March 2016

    This page is now on the Userbase wiki.