well the topic says it all actually.

How to boot a kernel only once with grub (like lilo -R <image>) so if it fails i can reboot the machine with a remote powerboot and it boot's the previous kernel (the one that did work)

thanks chris

well my questions say it all actually

1) does that mean your current grub is failing?

2) are you using an experiemental kernel and just need a choice in the menu.lst?

3) post your /etc/fstab and your /boot/menu.lst (or /etc/grub.conf) and someone should be able to help if I can't

I should have been nicer?

default 0

fallback 1

title this will be first if no option chosen
kernel etc
initrd etc

title fallback
kernel can be same but will need better appends
initrd can be same or different

I'm sorry, i missed your previous post, and no, you don't have to be nicer :-) helping/answering me is nice enough

my grub is not failing.

I don't have physical access to most of my machines, but they are connected to a remote powerboot.

So i want to do the following:

if i upgrade for example from 2.4.x to 2.6.x and i'm not sure my 2.6 kernel will boot

i do the following with lilo

set default kernel to 2.4.x and run lilo with lilo -R vmlinuz-2.6.x
this will boot the 2.6.x kernel once

if it boots i change the default to 2.6.x

If it doesn't boot I hit the remote powerswitch, the machine reboots and lilo wil load the old 2.4.x kernel so i can log in remote and fix 2.6.x

I have no idea how to do that with grub.

chris@chris:~$ cat /boot/grub/menu.lst|grep -v ^#
default 0
timeout 5
color cyan/blue white/blue
splashimage=(hd0,0)/boot/grub/splashimages/debsplash.xpm.gz

title Debian GNU/Linux, kernel 2.6.8.1
root (hd0,0)
kernel /boot/vmlinuz-2.6.8.1 root=/dev/hda1 ro
savedefault
boot

title Debian GNU/Linux, kernel 2.6.8.1 (recovery mode)
root (hd0,0)
kernel /boot/vmlinuz-2.6.8.1 root=/dev/hda1 ro single
savedefault
boot

title Debian GNU/Linux, kernel 2.4.26-1-386
root (hd0,0)
kernel /boot/vmlinuz-2.4.26-1-386 root=/dev/hda1 ro
initrd /boot/initrd.img-2.4.26-1-386
savedefault
boot

title Debian GNU/Linux, kernel 2.4.26-1-386 (recovery mode)
root (hd0,0)
kernel /boot/vmlinuz-2.4.26-1-386 root=/dev/hda1 ro single
initrd /boot/initrd.img-2.4.26-1-386
savedefault
boot

chris@chris:~$ cat /etc/fstab

proc /proc proc defaults 0 0
/dev/hda1 / ext3 defaults,errors=remount-ro 0 1
/dev/hda8 /home ext3 defaults 0 2
/dev/hda7 /tmp ext3 defaults 0 2
/dev/hda5 /usr ext3 defaults 0 2
/dev/hda6 /var ext3 defaults 0 2
/dev/hda9 none swap sw 0 0
/dev/hdc /media/cdrom0 iso9660 ro,user,noauto 0 0
/dev/fd0 /media/floppy0 auto rw,user,noauto 0 0
chris@chris:~$


my fstab

insert this line immediately after default 0 line in grub
fallback 2
(to boot the third entry)

2) delete savedefault lines from grub, keep it simple
3) delete boot lines not needed same reason
4) by remote powerboot I assume you mean you have set up your bios and kernel for power settings


5) glad to know your grub works or is it your kernel compiles that aren't working?