Chapter 7. Configuring your system to use kdm

Table of Contents

Setting up kdm

This chapter assumes that your system is already configured to run the X Window System®, and that you only need to reconfigure it to allow graphical login.

Setting up kdm

The fundamental thing that controls whether your computer boots to a terminal prompt (console mode) or a graphical login prompt is the default runlevel. The runlevel is set by the program /sbin/init under the control of the configuration file /etc/inittab. The default runlevels used by different UNIX® systems (and different Linux® distributions) vary, but if you look at /etc/inittab the start of it should be something like this:

# Default runlevel. The runlevels used by RHS are:
# 0 - halt (Do NOT set initdefault to this)
# 1 - Single user mode
# 2 - Multiuser, without NFS
# 3 - Full multiuser mode
# 4 - unused
# 5 - X11
# 6 - reboot (Do NOT set initdefault to this)


All but the last line of this extract are comments. The comments show that runlevel 5 is used for X11 and that runlevel 3 is used for multi-user mode without X11 (console mode). The final line specifies that the default runlevel of the system is 3 (console mode). If your system currently uses graphical login (for example, using xdm) its default runlevel will match the runlevel specified for X11.

The runlevel with graphical login (xdm) for some common Linux® distributions is:

  • 5 for Red Hat® 3.x and later, and for Mandrake

  • 4 for Slackware

  • 3 for SuSE®. 4.x and 5.x

The first step in configuring your system is to ensure that you can start kdm from the command line. Once this is working, you can change your system configuration so that kdm starts automatically each time you reboot your system.

To test kdm, you must first bring your system to a runlevel that does not run xdm. To do so, issue a command like this:

/sbin/init 3

Instead of the number 3 you should specify the appropriate runlevel for console mode on your system.

If your system uses Pluggable Authentication Modules (PAM), which is normal with recent Linux® and Solaris™ systems, you should check that your PAM configuration permits login through the service named kde. If you previously used xdm successfully, you should not need to make any changes to your PAM configuration in order to use kdm. /etc/pam.conf or /etc/pam.d/kde. Information on configuring PAM is beyond the scope of this handbook, but PAM comes with comprehensive documentation (try looking in /usr/share/doc/*pam*/html/).

Now it's time for you to test kdm by issuing the following command:

kdm -nodaemon

If you get a kdm login dialog and you are able to log in, things are going well. The main thing that can go wrong here is that the run-time linker might not find the shared Qt™ or KDE libraries. If you have a binary distribution of the KDE libraries, make sure kdm is installed where the libraries believe KDE is installed and try setting some environment variables to point to your KDE and Qt™ libraries.

For example:


If you are still unsuccessful, try starting xdm instead, to make sure that you are not suffering from a more serious X configuration problem.

When you are able to start kdm successfully, you can start to replace xdm by kdm. Again, this is distribution-dependent.

  • For Red Hat®, edit /etc/inittab, look for this line:

    x:5:respawn:/usr/X11/bin/xdm -nodaemon

    and replace with:


    This tells init(8) to respawn kdm when the system is in run level 5. Note that kdm does not need the -nodaemon option.

  • For Mandrake™, the X11 runlevel in /etc/inittab invokes the shell script /etc/X11/prefdm, which is set up to select from amongst several display managers, including kdm. Make sure that all the paths are correct for your installation.

  • For SuSE®, edit /sbin/init.d/xdm to add a first line:

    . /etc/rc.config
  • For FreeBSD, edit /etc/ttys and find the line like this:

    ttyv8   "/usr/X11R6/bin/xdm -nodaemon"  xterm   off secure

    and edit it to this:

    ttyv8   "/opt/kde/bin/kdm"  xterm   on secure
  • Most other distributions are a variation of one of these.

At this stage, you can test kdm again by bringing your system to the runlevel that should now run kdm. To do so, issue a command like this:

/sbin/init 5

Instead of the number 5 you should specify the appropriate runlevel for running X11 on your system.

The final step is to edit the initdefault entry in /etc/inittab to specify the appropriate runlevel for X11.


Before you make this change, ensure that you have a way to reboot your system if a problem occurs. This might be a rescue floppy-disk provided by your operating system distribution or a specially-designed rescue floppy-disk, such as tomsrtbt. Ignore this advice at your peril.

This usually involves changing the line:




When you reboot your system, you should end up with the graphical kdm login dialog.

If this step is unsuccessful the most likely problem is that the environment used at boot time differs from the environment that you used for testing at the command line. If you are trying to get two versions of KDE to co-exist, be particularly careful that the settings you use for your PATH and LD_LIBRARY_PATH environment variables are consistent, and that the startup scripts are not over-riding them in some way.