Chapter 4. Configuring kdm

This chapter assumes that kdm is already up and running on your system, and that you simply want to change its behavior in some way.

When kdm starts up, it reads its configuration from the folder $KDEDIR/share/config/kdm/ (this may be /etc/kde4/kdm/ or something else on your system).

The main configuration file is kdmrc; all other files are referenced from there and could be stored under any name anywhere on the system - but usually that would not make much sense for obvious reasons (one particular exception is referencing configuration files of an already installed xdm - however when a new kdm is installed, it will import settings from those files if it finds an already installed xdm).

Since kdm must run before any user is logged in, it is not associated with any particular user. Therefore, it is not possible to have user-specific configuration files; all users share the common kdmrc. It follows from this that the configuration of kdm can only be altered by those users that have write access to $KDEDIR/share/config/kdm/kdmrc (normally restricted to system administrators logged in as root).

You can view the kdmrc file currently in use on your system, and you can configure kdm by editing this file. Alternatively, you can use the graphical configuration tool provided by the System Settings (the Login Screen module in the System Administration category).

The remainder of this chapter describes configuration of kdm via the System Settings module, and the next chapter describes the options available in kdmrc itself. If you only need to configure for local users, the System Settings module should be sufficient for your needs. If you need to configure remote logins, or have multiple kdm sessions running, you will need to read on.

The Login Manager System Settings Module

Thomas Tanghus

Steffen Hansen

Mike McBride

Using this module, you can configure the KDE graphical login manager, kdm. You can change how the login screen looks, who has access using the login manager and who can shutdown the computer.


All settings will be written to the configuration file kdmrc, which in its original state has many comments to help you configure kdm. Using this System Settings module will strip these comments from the file. All available options in kdmrc are covered in Chapter 5, The Files kdm Uses for Configuration.

The options listed in this chapter are cross referenced with their equivalents in kdmrc. All options available in the System Settings module are also available directly in kdmrc but the reverse is not true.

In order to organize all of these options, this module is divided into several sections: General, Dialog, Background, Theme, Shutdown, Users and Convenience.

You can switch between the sections using the tabs at the top of the window.


You can only make changes if you run this module with superuser rights.


First you have a drop down box to choose the language for your login box, corresponding to setting Language in kdmrc.

In the Appearance section you have an option to use kdm in themed mode. If Use themed greeter is checked, the settings on the Dialog and Background pages cannot be configured separately.

While KDE's style depends on the settings of the user logged in, the style used by kdm can be configured using the GUI style: and Color scheme: options. These correspond to the keys GUIStyle and ColorScheme in kdmrc respectively.

From the Fonts section of this page you can change the fonts used in the login window. Only fonts available to all users are available here, not fonts you have installed on a per user basis.

You can select three different font styles in this section (General:, Failure:, Greeting:). When you click on the Choose... button a dialog appears from which you can select the new characteristics for the font style.

  • The General: font is used in all other places in the login window.

  • The Failure: font is used when a login fails.

  • The Greeting: font is the font used for the title (Greeting String).

You can also check the box labeled Use anti-aliasing for fonts if you want smoothed fonts in the login dialog.


From this page you can change the visual appearance of kdm, KDE's graphical login manager in non themed mode.

The Greeting: is the title of the login screen. Setting this is especially useful if you have many servers users may log in to. You may use various placeholders, which are described along with the corresponding key GreetString in kdmrc.

You can then choose to show either the current system time, a logo or nothing special in the login box. Make your choice in the radio buttons labeled Logo area:. This corresponds to LogoArea in kdmrc

If you chose Show logo you can now choose a logo:

  • Drop an image file on the image button.

  • Click on the image button and select a new image from the image chooser dialog.

If you do not specify a logo, the default $KDEDIR/share/apps/kdm/pics/kdelogo.xpm will be displayed.

Normally the login box is centered on the screen. Drag the anchor to move the center of the dialog to the desired position. Keyboard control is possible as well: Use the arrow keys or Home to center. Note that the actual proportions of the dialog are probably different. These correspond to the key GreeterPos in kdmrc.


Here you can change the desktop background which will be displayed before a user logs in. Selecting Enable background allows you to edit the options on this tab.

This tab is comprised of three areas:

  1. An area for selecting background images

  2. The background Preview Monitor

  3. An area for determining the background color

Preview Monitor

This is a preview window. It will give you a sense of what to expect with each change.


This section allows you to load a wallpaper on top of the color gradient chosen in the section below.

There are three choices available here:

No Picture

No picture background will be shown. The color and pattern choices below will still take effect.


A single picture will be used as the background for the selected desktops.

How this picture is positioned and scaled can be fine tuned below.

Slide show

KDE allows you to have an automatic slide show of wallpaper images. To enable this option, press the Setup... button. In the resulting dialog you may choose any image or folder of images available on your computer, using the Add... button to navigate your file system. Remove will remove the currently selected entry from the list.

You may choose the length of time any image is displayed in the Change picture after: box, and you may choose Show pictures in random order if you don't want them displayed in the order they are listed.


Displaying wallpaper requires that the image be kept in memory. If you are low on memory, using a small, tiled image or none at all is recommended.

Scaling or centering a small image still requires an image the size of your display to be maintained in memory.




The image will be centered on the screen without changing the size of the image. The background colors will be present anywhere the image does not cover.


The image will be duplicated until it fills the entire desktop. The first image will be placed in the upper left corner of the screen, and duplicated downward and to the right.

Center Tiled

The image will be duplicated until it fills the entire desktop. The first image will be placed in the center of the screen, and duplicated upward, downward to the right, and to the left.

Centered Maxpect

The image will be placed in the center of the screen. It will be scaled to fit the desktop, but it will not change the aspect ratio of the original image. This will provide you with an image that is not distorted.

Tiled Maxpect

The image will be placed in the corner of the screen. It will be scaled to fit the desktop, but it will not change the aspect ratio of the original image. This will provide you with an image that is not distorted. If there is any space over, the image will be duplicated to fill it.


The image will be scaled to fit the desktop. It will be stretched to fit to all four corners. This may distort the image.

Centered Auto fit

If the picture fits the desktop size, this mode works like the centered option. If the picture is larger than the desktop then it is scaled down to fit while keeping the aspect ratio.

Scale & Crop

Magnify the picture without distorting it until it fills both the width and height of the desktop (cropping the picture if necessary), and then center it on the desktop.


The first drop down box allows you to choose the type of color, gradient, or pattern to display under (or in place of) wallpaper.


If you are going to be using a picture as a wallpaper, you can skip this section of the dialog box.

However, if your chosen wallpaper does not cover the entire desktop, the chosen colors will still show in the remaining space.

Single Color

By choosing this mode, you select one color using the first color bar, and the entire background is covered with this one color.

Horizontal Gradient

By choosing this mode, you select two colors (using both color buttons). KDE will then start with the primary color selected with the left button on the left edge of the screen, and slowly transform into the blend color selected with the right button by the time it gets to the right edge of the screen.

Vertical Gradient

By choosing this mode, you select two colors (using both color buttons). KDE will then start with the primary color selected with the left button on the top edge of the screen, and slowly transform into the blend color selected with the right button as it moves to the bottom of the screen.

Pyramid Gradient

By choosing this mode, you select two colors (using both color buttons). KDE will then start with the primary color selected with the left button in each corner of the screen, and slowly transform into the blend color selected with the right button as it moves to the center of the screen.

Pipecross Gradient

By choosing this mode, you select two colors (using both color buttons). KDE will then start with the primary color selected with the left button in each corner of the screen, and slowly transform into the blend color selected with the right button as it moves to the center of the screen. The shape of this gradient is different than the pyramid gradient.

Elliptic Gradient

By choosing this mode, you select two colors (using both color buttons). KDE will then start with the blend color selected with the right button in the center of the screen, and slowly transform into the primary color selected by the left button as it moves to the edges, in an elliptical pattern.


The rest of the list are the names of various patterns or textures you can choose.

For more on patterns, see the section Adding, Removing and Modifying Patterns.

Select the primary color with the first color bar. If you have chosen a pattern that requires two colors to be set the secondary color can be set by pressing the appropriate button.


The drop down box labeled Blending: contains the options to make a smooth transition (blend) from the wallpaper as it changes to the background.

  1. A drop down box allows you to select the blending mode. Many of the modes are similar to blending modes for background colors. Select your mode from the list, and the preview window shows you what it will look like.

  2. The Balance slider adjusts the blending. The results can be seen immediately in the preview window.

  3. The Reverse roles can reverse the role of the picture and the background for some types of blending.

Advanced options

Located below the preview monitor is a button labeled Advanced Options.

To use an external program to determine and change the background of KDE, simply select Use the following program for drawing the background. Available KDE programs are listed, select one to enable it.

Adding, Removing and Modifying Wallpapers and Patterns

There is a button under the preview monitor labeled Get New Wallpapers that helps you fetch new wallpaper images from a selection of popular images from the KDE-Look website. You can of course select any image you have available to use as wallpaper, and it may be stored in any location on your hard drive. To have a wallpaper show up in the list automatically for all users, you should save it to the $KDEDIR/share/wallpapers folder.

A pattern is a picture file which KDE uses as a template to draw your background. The picture file provides the shapes, but KDE provides the colors. KDE is packaged with several patterns, and you also can add new patterns.

To add a new pattern that is available to every user on your computer, simply place the file in $KDEDIR/share/apps/kdm/patterns/.

Copy a .desktop file from this folder, and name it the same as your new pattern image file. Modify the contents to suit your new pattern.

To add a new pattern for a single user, add the files to $KDEHOME/share/apps/kdm/patterns/.

For best results, the pattern should be a grayscale PNG file.


This page consists of three sections:

A list of installed themes, where you can select the one to be used.

A screenshot with a preview of the selected theme and additional information like Copyright and Description.

Three buttons to install or remove a theme and a button to launch the Get Hot New Stuff dialog where you can download new themes.


The settings on this page are only available in themed mode.


Allow Shutdown

Use this drop down box to choose who is allowed to shut down:

  • Nobody: No one can shutdown the computer using kdm. You must be logged in, and execute a command.

  • Everybody: Everyone can shutdown the computer using kdm.

  • Only Root: kdm requires that the root password be entered before shutting down the computer.

You can independently configure who is allowed to issue a shutdown command for the Local: and Remote: users.


Use these text fields to define the exact shutdown command.

The Halt: command defaults to /sbin/halt. The Reboot: command defaults to /sbin/reboot.

When Boot manager is set to Grub or Lilo, kdm will on reboot offer you options for these boot managers. Note that this option is not available on all operating systems.


From here you can change the way users are represented in the login window.

Independently of the users you specify by name, you can use the System UIDs to specify a range of valid UIDs that are shown in the list. By default user id's under 1000, which are often system or daemon users, and user id's over 30000, are not shown.

You may disable the user list in kdm entirely in the Users section. You can choose from:

Show list

Only show users you have specifically not excluded in the list alongside

If you do not check this box, no list will be shown. This is the most secure setting, since an attacker would then have to guess a valid login name as well as a password. It is also the preferred option if you have more than a handful of users to list, or the list itself would become unwieldy.


If this option is checked, kdm will automatically complete user names while they are typed in the line edit.

Inverse selection

Allows you to instead select a list of users that should be shown, and all other users will not be listed.

You can also enable the Sort users checkbox, to have the user list sorted alphabetically. If this is disabled, users will appear in the order they are listed in the password file. kdm will also autocomplete user names if you enable the Autocompletion option.

If you choose to show users, then the login window will show images (which you select), of a list of users. When someone is ready to login, they may select their user name/image, enter their password, and they are granted access.

If you permit a user image, then you can configure the User Image Source:

Here you can specify where kdm will obtain the images that represent users. System represents the global folder; these are the pictures you can set below. User means that kdm should read the user's $HOME/.face.icon file. The two selections in the middle define the order of preference if both sources are available.

If you choose not to show users, then the login window will be more traditional. Users will need to type their username and password to gain entrance. This is the preferred way if you have many users on this terminal.


In the Convenience tab you can configure some options that make life easier for lazy people, like automatic login or disabling passwords.


Please think more than twice before using these options. Every option in the Convenience tab is well-suited to seriously compromise your system security. Practically, these options are only to be used in a completely non-critical environment, e.g. a private computer at home.

Automatic Login

Automatic login will give anyone access to a certain account on your system without doing any authentication. You can enable it using the option Enable Auto-Login.

You can choose the account to be used for automatic login from the list labeled User:.

With Lock session the automatically started session will be locked immediately (provided it is a KDE session). This can be used to obtain a super-fast login restricted to one user.

Automatic login can be suppressed by pressing the Shift key immediately after the X-Server switches to graphics mode and releasing it when kdm's hourglass cursor appears.

Preselected User

You can also choose which user is preselected when kdm starts. The default is None, but you can choose Previous to have kdm default to the last successfully logged in user, or you can Specify a particular user to always be selected from the list. You can also have kdm set the focus to the password field, so that when you reach the kdm login screen, you can type the password immediately.

Password-Less Login

Using this feature, you can allow certain users to login without having to provide their password. Enable this feature using the Enable Password-Less Logins option.

Below this option you'll see a list of users on the system. Enable password-less login for specific users by checking the checkbox next to the login names. By default, this feature is disabled for all users.


Again, this option should only be used in a safe environment. If you enable it on a rather public system you should take care that only users with heavy access restrictions are granted password-less login, e.g. guest.

The Automatically login after X server crash option allows you to skip the authentication procedure when your X server accidentally crashed.