Being GRUBby only once

The 'grubonce' command is a pretty little script if you are playing with various kernels. Basically, it lets you pick a GRUB menu boot option that it will boot from once and then go back to booting the old default. This is handy if you want to test out a new kernel and you want a safe way to check it out. This way, if the boot fails, your reboot will be back into the 'good' option. It is an undocumented perl script found in /usr/sbin, and looks like it implements this algorithm for you:

Booting once-only - GNU GRUB Manual 0.97

$ su -
Password: my root password
# grubonce
0: OpenSUSE 10.2 - Kernel-2.6.18.8-0.1-default
1: linux (/dev/hdb6)
2: Windows
3: Floppy
4: Kernel-2.6.18.8-0.1-xen
# grubonce 4
Using entry #4: Kernel-2.6.18.8-0.1-xen
# ^d
$

Pretty slick if you ask me!