Re: Query about command line commands

[Andrei Borzenkov]

В Tue, 10 Mar 2015 14:46:46 +0800
Bret Busby <address@hidden> пишет:

> >>
> >
> > How do you get this grub command line interface? Does your system boot into
> > it?
> >
> 
> By pressing <ESC> while booting, to display the PC-BSD "boot menu"
> (which displays as the only boot option, the unbootable PC-BSD
> installation) which has, at the bottom of the screen "Press enter to
> boot the selected OS, 'e'to edit the commands before booting or 'c'
> for a command line"; the command line being the GRUB CLI.
> 
> > If you are in grub CLI you could boot Ubuntu (from your grub.cfg
> > attached earlier) by using the same commands as in grub.cfg:
> >
> > set root=hd0,gpt12
> > linux    /boot/vmlinuz-3.13.0-40-generic
> > root=UUID=b96339a3-179e-4891-972e-658d35c454a6 ro

This was one line which was wrapped by mailer. Sorry.

> > initrd    /boot/initrd.img-3.13.0-40-generic
> > boot
> >
> > You could try to omit root= but I do not know what Ubuntu does in this
> > case. You can verify UUID by using "ls -l" on grub command line.
> >
> 
> When I entered the command starting with "initrd", I got the response
> "disk 'UUID=<UUID>' not found".
> 

That's because you did

root=UUID=b96339a3-179e-4891-972e-658d35c454a6 ro

which assigned string "UUID=b96339a3-179e-4891-972e-658d35c454a6" to
$root variable. $root is default disk (partition) which is always
searched when not given explicitly on command line.

So once more

line 1:
set root=hd0,gpt12

line 2 (if even you see it split in multiple lines by mailer):
linux /boot/vmlinuz-3.13.0-40-generic 
root=UUID=b96339a3-179e-4891-972e-658d35c454a6 ro

line 3:
initrd /boot/initrd.img-3.13.0-40-generic

line 4:
boot


> 
> > Oh, regarding platform - what
> >
> > echo $grub_platform
> >
> > in grub command line says?
> >
> 
> "
> grub> echo $grub_platform
> pc
> "
>

As expected, you have no EFI boot. In this case on GPT disk on BIOS you
can really have a single bootloader. 

> 
> But, whilst, mat the start of the boot process, is displayed
> 
> "GRUB Loading
> Welcome to GRUB"
> 
> No reference to Microsoft, or, to MIS Windows, as a boot option, is displayed.
> 

Because your Windows installation does not have legacy bootloader and
it is impossible to load EFI bootloader when you already booted in
legacy BIOS mode.