Is there a best-practice way of dealing with a system crash or a system freeze? I know of the "force-quit" keyboard shortcut. But what if it doesn't work? I just bought a MacBookPro and I am switching from Linux. In Linux there is a possibility to shutdown the X window system, and log in from a text console, or one can communicate with the kernel directly via magic SysRq-key, and for example, remount a hard disk read-only or reboot the system.
If force-quitting doesn't work you have a few options:
The relationship between Mac OS X and the Unix underpinnings aren't the same as they are between X window/GNOME and the kernel. It isn't nearly as open, so there is really no messing with the kernel near as I can tell in Mac OS X. I usually go the route I mentioned above and as long as I maintain the system properly and regularly I always seem to get back on my feet without any problems.