Here's what my .xinitrc has
All it does is start gnome when you start X. If you use KDE it would say
You can create a .xinitrc manually if its really not there. An ls -al /home/knoppix will let you know for sure.
Try to start X by passing the full path
If that works, then you simply need to add /usr/X11R6/bin to the PATH variable. You can verify that PATH is missing /usr/X11R6/bin by
You will get a colon seperated list of directories that are "looked in" for any program you try to execute without using the full path.
There are a couple of ways to make sure /usr/X11R6/bin is in the PATH variable. I'd probably just add it to the global profile if I was setting up a PC for my sister (which I don't actually have). Look for sometihing like
if [ "$EUID" = "0" ] || [ "$USER" = "root" ] ; then
in /etc/profile. In the else part, add /usr/X11R6/bin so it looks like this