kded4(8) triggers Sycoca database updates when needed.


kded4 [--help] [Generic options] [Qt-options] [KDE-options] [--check]



is responsible for creating the sycoca file, i.e. the binary cache of servicetypes, mimetypes, and services for a particular user.

It monitors the directories containing .desktop files. When a file is added/removed, it waits 5 seconds (in case of a series of updates), and then launches kbuildsycoca4 to update the sycoca.

It checks newly installed update files, i.e. the *.upd files used to update configuration files of users when the configuration file formats changes. kconf_update is launched to do the updates.

When the hostname changes, it will make the necessary changes to the KDE environment and X-server to allow continued proper operation, launching kdontchangethehostname to do the changes.

Those tasks are also performed always at kded4 start to ensure that the user configuration is up to date.

It is also responsible for launching the on-demand kded4 modules and init enabled kded4 modules like:

Konqueror Browser Preloader

Reduces Konqueror startup time.

Directory Watcher

Monitors directories for changes.

Hardware Detection

Provides a user interface for hardware events.

SSL Certificate Policy

Provides the user configured SSL certificate policy to applications.

Network Proxy Configuration

Automatic proxy configuration.

Password Caching

Temporary password caching, for example: so that a webpage with HTTP authentication doesn't ask for your password for every link and every image in the page. These passwords are forgotten when exiting KDE (unlike KWallet)

Sound Policy

Provides the sound system policy to applications.


Stores website icons.

Display Management

Manages displays and video outputs.

Cookie jar

Stores network cookies.

Network Watcher

Keeps track of the network and updates directory listings of the network:/ KIO slave.

Subversion Module

Provides various subversion actions to filemanager and other software.

Network Status

Tracks status of network interfaces and provides notifications for applications using the network.

Write Daemon

Watches the messages from local users sent with write(1) or wall(1).

Notification area watcher

Keeps track of applications that want to use the D-Bus based notification area.


KMixD Mixer Service

Systemtray daemon

Keeps track of applications that want to use the D-Bus based system tray.

Keyboard Daemon

Keeps track of keyboard changes (new keyboard, changed layout)

Remote URL Change Notifier

Provides change notifications for network folders

Activity Manager

The Nepomuk activities manager backend

Display Management change monitor

Notifies how the display has been rotated (where available)

Free Space Notifier

Warns when running out of space in your home folder.

Removable Device Automounter

Automatically mounts devices as needed.

Nepomuk Search Module

Helper module for KIO to ensure automatic updates of Nepomuk search listings.

Power Management

Battery, Display and CPU power management and notifications.

K Remote Control Daemon

Manages the Remote Control commands received

Status Notifier Manager

Manages services that provide status notifier user interfaces.

DNS-SD Service Discovery Monitor

Monitors the network for DNS-SD services.

Drive Ejector

Automatically unmounts and releases drives when their eject button is pushed.

Time zone

Provides access to the system's time zones for applications.

Input Actions

Input Actions service performing configured actions on key presses.

The init modules can be enabled/disabled using systemsettings, in System Administration > Startup and Shutdown > Service Manager.



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Check Sycoca database only once.


If kded4 is called without parameters and is already running, it shows the message:

KDE Daemon (kded) already running.

If kded4 is called with kded4 --check, then it updates the KDE sycoca using kbuildsycoca4.


There are probably tons of bugs. Use m[blue]bugs.kde.orgm[][1] to report them.


David Faure <[email protected]>


Waldo Bastian <[email protected]>