At least on a PC architecture, Ctrl+Alt+Delete sends a software interrupt to the init process, which processes it as per the ctrlaltdel entry in the /etc/inittab file.
In the /etc/inittab file, you may have a line looking something like this:
# What to do when CTRL-ALT-DEL is pressed.
ca:12345:ctrlaltdel:/sbin/shutdown -t1 -a -h now
If so, modify it like below. If not, add a new one like below:
Now create a script file, and save it as /etc/onctrlaltdel. The file should read something like:
I don't know what the KDE process manager is called or where it resides on your particular system; you may need to change the /opt/kde3/bin/kdeprocman bit (“echo $KDEDIR” might tell you where to start looking).
Mark your script as executable:
chmod a+rx /etc/onctrlaltdel
. It should now run (as root) every time you press Ctrl+Alt+Del.
Btw, the DISPLAY=:0.0 bit just sets up an environment variable ($DISPLAY) that tells the program which X-windows display to open on.
I hope that's of some help,
— Robert J. Lee