[lug] Mad Mice and X Windows

[Bonnell, Doug]

Since this is such a widely seen problem, I'd like to offer my tips
on how to deal with this situation. First, a little background:

	1. Most Linux systems have the concept of a "runlevel".
	    The runlevel tells the system what programs to run
	    after powerup. If X windows is to be on, the runlevel that
	    it is enabled in will call an X "login manager". This is
	    gdm for Gnome (under RedHat), kdm for KDE or xdm.

	2. If you are doing any kind of tinkering with X, find a 
	    runlevel that doesn't startup X. Under RedHat, X is
	    started at runlevel 5, while under SUSE it's runlevel 3.

	    Select runlevel 3 as the default for RedHat or runlevel 2
	    for SUSE. The default runlevel is usually specified in the
	    file /etc/inittab. This will prevent X from starting on it's
own.
	    You will have to tell X to start, and this gives you the power
	    to stop it as you see fit.

OK, so much for preventing being stuck forever in X windows with a
mad mouse. But, how do you handle the situation where you messed
up the mouse configuration or the mouse just died?

You will need to bootup a rescue diskette (you did make one, didn't you?).
Once up, mount your harddrive's root partition ( usually /dev/hda1 ) at
some available place such as /mnt. Somehow, edit the inittab on your
harddrive so the default runlevel will not start X, then reboot the system
(using the harddrive, of course). This should restore your system to a sane
(without X) state.

Lastly, you need to either use the X setup/configuration tools for your
distribution to fix your mouse settings under X or manually edit the file
"XF86Config". Distributions like to move this file around. It's under
/etc/X11
on RedHat and /etc for SUSE. There is a section pertaining to the pointer
device and this is likely what was changed that caused the mouse to go
mad.

You can test different settings in XF86Config by starting X ( with xstart ).
If the X server can't come up, you will return to your shell and see the
error
messages. If the mouse is mad, you can exit X with Ctrl-Alt-BackSpace
and you will return to your shell.

I hope this all wasn't too boring for those of you who already know about
all of this.

Regards,
Doug Bonnell
Software Engineer
BreeceHill Technologies Inc.