Grubs Batch Feature

In grub.conf you have default= yeah,  where you specify which kernel is booted. leave this set to a kernel that you know is good and working. then to test a new kernel, you can tell grub to try that kernel only once with this command before you reboot

echo "savedefault --default=0 --once" | grub --batch


 if the server hangs, get the customer to reboot the server and it will then go back to the good kernel from grub.conf