Re: Query about command line commands

[Andrei Borzenkov]

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.

If you are using EFI system, bootloaders are installed in ESP (EFI
System Partition) which is likely what you listed below

> ls (hd0,gpt2)/
> efi/
> ls (hd0,gpt2)/efi/
> Microsoft/ Boot/ oem/
> ....
> "
> 

And firmware keeps list of boot entries that refer to file on ESP. So
usually to fix booting on EFI it is enough to fix firmware list of boot
entries or simply set default boot entry. But if your output above is
correct, you do not have any boot entries at all (besides Microsoft).
Dud you install your Linux systems in EFI or BIOS mode?