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KDE provides an enhanced replacement (kdm
) for the
"X Display Manager" (xdm
), which provides the
X Window system login screen.
For troubleshooting purposes,
it is useful to know that kdm
runs independently
of the KDE desktop - the only connection is that the KDE desktop
provides a graphical interface for configuring kdm
.
In particular,
kdm
without running the KDE desktop
(just use it as an X Display
Manager to run X Window sessions with the default Red Hat window manager);kdm
, by
using the original Red Hat X Display Manager xdm
,
or without a display manager at all ("startx
").The KDE X Display Manager kdm
in general uses the same
configuration files as xdm
; one exception is that kdm
can be configured at compilation time to use its own configuration
file for PAM (Pluggable Authentication Modules), Red Hat's password
checking system, and this has been done in these RPM packages.
A (bash) shell script kdm_on is provided to edit
two of the default Red Hat X Window system configuration
files: /etc/inittab
,
(to make kdm
the default X Display Manager in runlevel 5, instead
of xdm
), and
/etc/X11/xdm/Xsetup_0
(to allow the background wallpaper of
the X Window system login screen to be configurable from the
KDE desktop).
All the system administrator needs to do to
make these changes is to type
kdm_on
A second shell script kdm_off is available if
the system administrator wishes to reverse this
(type "kdm_off
") to again make
xdm
the default X Display manager.
Both scripts save copies of the original files
(as /etc/inittab.kdesave
, /etc/X11/xdm/Xsetup_0.kdesave
).
If you uninstall KDE, the kdm_off
script is run as part of
the uninstallation script of the kdesupport
RPM package.
Unlike xdm
, the kdm
login screen has a "shutdown" button, that allows the
system to be shut down. The kdm
configuration initially installed
by this RPM package allows system shutdown by any user, but
the System Administrator can configure kdm
in the KDE Control Center
so a dialog box requiring the Root password opens
when "shutdown" is pressed.
This dialog box presents three options:
kdm
process, or type "telinit 3
" if the system is in runlevel 5.)If you wish to allow system shutdown without requiring the root
password to be given, you (as root
) can configure this
using the KDE control center when the KDE Desktop is running.
The KDE Control Center (or the "K --> Settings" menu)
has a graphical interface
("Applications --> Login Manager") for configuring kdm
, including
shutdown privileges. Selections "All" or "Console Only" in "allow to shutdown"
on the "Sessions" screen, allows anyone to shut the system down without being
prompted for a password. You can also do this manually by editing
the kdm configuration file /opt/kde/share/config/kdmrc
:
just change the line "ShutdownButton=RootOnly
" to
"ShutdownButton=ConsoleOnly
".
The change made to /etc/X11/xdm/Xsetup_0
by the
kdm_on
script allows the background wallpaper of
the X Display Manager login screeen to be configured by
the System Manager, using the "Applications --> Desktop Manager"
selection in the KDE Control center.
However, if you prefer to keep the Red Hat login screen background
(a banner saying "Red Hat Linux", with a picture of the Linux penguin
logo ("Tux") in a red hat), edit /etc/X11/xdm/Xsetup_0
to
delete the last line "/opt/kde/bin/kdmdesktop
", which
was added by the kdm_on
script.
(This will disable display of configurable backgrounds for the login screen).
Like Red Hat's xdm, kdm (and the KDE screensaver lock) uses the PAM (Pluggable Authentication Module) system for authenticating users (i.e. password checking). This will transparently handle shadow passwords, for example, and can be configured to use many different authentication schemes.
KDE's PAM service (called "kde") is configured by the file
/etc/pam.d/kde
.
If this file does not exist, the kdebase
RPM package
installs a default version (a copy of
the Red Hat default /etc/pam.d/xdm
).
If the kdebase RPM is uninstalled, and the kde PAM configuration file is
different from this default file, it is saved as
/etc/pam.d/kde.rpmsave
.
Note that kdm
(unlike Red Hat's xdm
) implements
"PAM session" support, so
new PAM customizations are possible. See the PAM documentation in /usr/doc/pam-*
to learn what you can do with PAM, and how to configure it
with a customized
/etc/pam.d/kde
.
If /etc/pam.d/kde
is deleted or corrupt, you will not be able to
login under kdm (hopefully you can access the system through a console,
in that case). A quick fix if this happens is for root
to copy
/etc/pam.d/xdm
to /etc/pam.d/kde
.
Even if you do not use kdm, the pam service "kde" should be configured,
as it also provides password authentication services to
kcheckpass
, used by the KDE screen lock.
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