I used rsync to back up my data from Vbox. I replaced the fstab of the backup with the fstab of a fresh install. I then used that data to restore everything on the same fresh install. Now I'm unable to update my grub as no commands work. I have permission denied on every command. Is there a way to get back those permissions. And if not is there any way by which I can use all the applications and settings of my Vbox install on the fresh install. I have access to that Vbox install. Also I have a complete rsync backup of that install on an external drive.
What do you want to restore? Usually you backup only your home folder, and some other stuff you need that you have put somewhere.
I do not recommend you to restore the whole system, well you can do that, but that is usually not what you want to do. Follow this guide if you really want to backup the whole system.
Taking care of grub can be a bit of a hassle. I suggest you mount all your backed up stuff, then bind
/proc into the mounted root and
chroot into the restored root. In there you can use
grub-install /dev/<something> to install grub.
mount /dev/sdBla /mnt/new_root mount -o bind /dev /mnt/new_root/dev mount -o bind /sys /mnt/new_root/sys mount -t proc /proc /mnt/new_root/proc chroot /mnt/new_root
The permission denied is strange, is assume you are
root? Do the files have the right architecture? (32/64bit, depending on the installed system) Try
file $(readlink -f $(which grub-setup)) and take a look if it matches your system.