Re: Query about command line commands

[Andrei Borzenkov]

On Mon, Mar 9, 2015 at 12:01 PM, Bret Busby <address@hidden> wrote:
> On 09/03/2015, Andrei Borzenkov <address@hidden> wrote:
>> В Mon, 9 Mar 2015 16:17:16 +0800
>> Bret Busby <address@hidden> пишет:
>>
>>> Hello.
>>>
>>> On a problem system, I have "GNU GRUB version 2.02~beta2"
>>> as shown in the command line window.
>>>
>>> The system is a UEFI/GPT system.
>>>
>>> Three or four operating systems are apparently more or less installed
>>> on the system, and the installation attempt of the last operating
>>> system, broke everything.
>>>
>>> I have found that I am able, at the GRUB command line, to run ls,
>>> which returns a list of the partiitions (hd0,gpt<x for x= 1 to 13>).
>>>
>>> I can also run ls (hd0,gpt<x>), which returns a description of the
>>> partition filesystem.
>>>
>>> I can also run ls (hd0,gpt<x>)/ , which lists the top level contents
>>> of the partition.
>>>
>>> Now, my query is this; with the command set that is available at that
>>> level, can I mount a USB thumb drive (eg, mount <device descriptor>
>>> <mount device name> (I do not know whether that would the the order of
>>> the syntactical components, or, what would be the correct syntax),
>>
>> grub does not "mount" anything. It enumerates devices using firmware
>> interfaces (BIOS or EFI) and provides you with names. So to access USB
>> stick you would need to plug it before booting and it will be available
>> in grub as hdX (note that exact number depends on order in which EFI
>> probes for them).
>>
>>> and, direct a copy of each command and return output, to a file on the
>>> USB drive, eg, where I have
>>>
>>
>> No. GRUB does not support writing to a filesystem. Nor do I quite
>> understand what you are trying to do here and how would it help you.
>>
>
> I figured that if I would be able to do what I want, with ouputting
> the information to a USB drive file, I would be able to show what is
> in each partition, so as to be able to select the appropriate one(s)
> for restoration of the system, to an operable computer system with
> which I could select which operating system I want to boot.
>

To list filesystem it is more easy and convenient to use live Linux dstro.

> Whilst the last operating system that was attempted to be installed,
> PC-BSD, is an operating system that I now consider too dangerous to
> try again, due to the damage that it has done, and, therefore, I do
> not want to be able to boot that operating system, the computer has
> had (and apparently, still has) an installation of MS Windows 8, then
> it had Debian 7 installed, thence the MS Win8 installation could not
> be found,

Which just confirms that you installed Windows and Linux in different
modes. Because ESP lists \EFI\Windows it is strong hint that Windows
was installed in EFI and Linux is installed in BIOS mode.

>                and then it had Ubuntu 14.04 LTS installed, and, the Ubuntu
> installation, with its acompanying GRUB, found Ubuntu and Debian, and,
> I was thence able to boot into either Ubuntu of Debian (but, not MS
> Windows),

Again.

>                  and, when PC-BSD was kind of installed, it buried everything
> else on the system, and, is inoperable, leaving me with a mostly
> inoperable computer. About the only thinbg that now works on the
> computer, is the GRUB 2.02 beta2 command line interface, with which I
> am mostly unfamiliar, beyond getting the ls command to work, as much
> as I have been able to get it to work.
>

How do you get this grub command line interface? Does your system boot into it?

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
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.

Oh, regarding platform - what

echo $grub_platform

in grub command line says?