Re: Query about command line commands

[Bret Busby]

On 09/03/2015, Andrei Borzenkov <address@hidden> wrote:
> 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?
>

Have to finish for today.

Hopefully, will be able to try again tomorrow.

-- 
Bret Busby
Armadale
West Australia
..............

"So once you do know what the question actually is,
 you'll know what the answer means."
- Deep Thought,
 Chapter 28 of Book 1 of
 "The Hitchhiker's Guide to the Galaxy:
 A Trilogy In Four Parts",
 written by Douglas Adams,
 published by Pan Books, 1992

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