confusing GRUB2 - how do I set a given kernel?

[TomaszC]

I find GRUB2 somehow very confusing in configuration.

Supposing I have these kernel installed, plus, my own kernel in /boot/vmlinuz-custom:

# dpkg -l|grep linux-image
ii linux-image-2.6.35-22-generic
ii linux-image-2.6.36-020636rc8-generic

How can I make i.e. /boot/vmlinuz-custom a default boot entry?

For example, /etc/default/grub only has "GRUB_DEFAULT=0", which doesn't say which of these kernels it will be (i.e. vmlinuz-default, 2.6.35, or 2.6.36-rc*). /etc/grub.d/ is no less confusing.

In GRUB (legacy), it was a simple matter of adding a line to menu.lst - how do I do it with GRUB2?

[drs305]

You can see how to set the default OS or kernel by visiting this thread:
GRUB 2 - 5 Common Tasks


The kernel you want should be in the /boot folder.
Update grub with the following if you just added the new kernel:

sudo update-grub

In summary:

1. View the entries in your Grub menu:
   

   grep menuentry /boot/grub/grub.cfg

2. Count to the entry you want, starting with 0. (The first menuentry is 0, the second is 1, etc)
3. Open /etc/default/grub as root:
   

   gksu gedit /etc/default/grub

4. Change this value to the one you want:
   

   GRUB_DEFAULT=0

   Save the file.
5. Update grub
   

   sudo update-grub

There are a variety of links in my signature line which explain how to understand and use Grub 2.