Boot from GRUB commandline

There may be occasions where we need to boot manually from the GRUB menu and perhaps realize that you should just have installed LILO in the first place :)

When the boot menu shows, interrupt the automatic selection by using one of the arrow keys or press e to edit the highlighted selection. Instructions are provided but CTRL-X will boot your modified script, while CTRL-C drops you to a command line, which is what we will discuss here;

Firstly, to prevent scrolling, we can use set pager = 1

We can use ls to list all disks and partitions.

From there, we can use, for example ls (hd0, gpt1)/ or ls (hd0,1)/ to show the contents of that partition. 

Similarly, we can look inside directories with ls (dh0,1)/etc

What we are looking to find is the root partition (I believe this refers to /, but I'll need to consider if this is the case when /boot is on a different partition).

1). We set the root partition with, for example set root=(hd0,1)

We can see the current root setting by entering the root command by itself.

We then need to tell it where the linux kernel and initrd image are and we do this as follows;

2). linux /boot/vmlinuz-some-version-number root=/dev/sda1 (if the root partition is on sda1 of course)

3). initrd /boot/initrd-img-some-version-number

4). Finally, we boot with the new settings with boot