Re: Why are the following mounts needed before running grub-install ?

[Xen]

Sreyan Chakravarty schreef op 07-08-2017 19:18:
> Can someone explain to me why in case of a chroot environment why the
> following mounts are necessary before running grub-install or 
> update-grub ?
>
> $ mount -t proc none /mnt/ubuntu/proc
> $ mount -o bind /dev /mnt/ubuntu/dev
> $ mount -o bind /sys /mnt/ubuntu/sys

I don't have a full explanation but these directories are used to access 
system information and devices, they are in effect a form of system call 
to the system.

Without these systems mounted in the default trees, these system calls 
cannot be made, so to speak.

It's a bit silly perhaps that there is no easier way to do it (a lot of 
manual headaches) (particularly if you want to unmount something after 
the fact etc. etc.) but this is your way to give your chroot environment 
and its programs access to these system 'functions'.

Btw, the following is supposed to be equivalent:

mount --bind /proc /target/proc
mount --bind /dev /target/dev
mount --bind /sys /target/sys

Which is what I always use. (/target is where your target system is 
mounted during installation, it is the same as the /mnt/ubuntu/... you 
use).

There really should be an option to "chroot" that does this, I think.

But anyway, regards.