How to cause an installation failure in the %pre script

[Gianluca Varenni]

Hi all.

I'm preparing a custom Fedora 10 Install CD with kickstart. In the %pre 
script, I check the presence of a specific RAID controller (and disks) and 
reconfigure it. If the RAID controller is not there (or something fails 
during the reconfiguration), I need to fail the installation of Fedora.

Is there a way from the %pre script to return a failure?

Have a nice day
GV