Re: determining root mounting point from GRUB command line prior to boot

[Blue Upsilon]

thanks Steve;  but this does not solve my problem.
to be more clear this is what i do when i boot:
======
grub> set root=(hd0,gpt4)
grub> linux /vmlinuz root=/dev/nvme0n1p4
grub> initrd /initrd.img
grub> boot
======

this works;
but line #2  can be problematic in some cases.
say i'm booting from an external disk backup.
then in line 2,    i don't know what to set root equal to.
if I do:     ls  /dev    then it does not show the various sda1,sdb2,nvme0n1p4; 
etc etc.

the only way i see these is:   say i don't set a root=...  argument,   then the 
boot FAILS,     and i get to BusyBox  with an initramfs command line.
in this command line,  if i do    ls /dev      THEN  i do see the various   
/dev/nvme0n1p4,   etc etc....
but,  is there a way to see these in GRUB command line?   that way i can know 
what to set the root arg equal to.......

Cheers,
Blue

‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Monday, May 27, 2019 9:28 PM, Steve <address@hidden> wrote:

> type
> ls
> it will list all partitions and drives
>
> On Mon, 27 May 2019 at 19:26, Blue Upsilon via Help-grub <address@hidden> 
> wrote:
>
>> Hi there,
>>
>> I use Ubuntu 18.04.
>> When I boot from GRUB command line, is there a way to determine what the 
>> root mounting point will be, before booting?
>>
>> i.e., say I know that my partition that has Ubuntu is  (hd0,gpt4).
>> so then I do:     set root=(hd0,gpt4)
>> and then I happen to know that the correct root mounting point is   
>> /dev/nvme0n1p4
>> so then I know to do:    linux /vmlinuz root=/dev/nvme0n1p4
>> and then i do     initrd /initrd.img     and  boot
>>
>> but like what if i don't know ahead of time that    /dev/nvme0n1p4   is what 
>> I need?
>> (this problem comes up when:   say i'm booting from a backup external disk, 
>> and i don't know whether it will be /dev/sdb2  or whatever.... etc..)
>>
>> Thanks,
>> Blue Upsilon
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