On Sun, Jul 5, 2015 at 4:43 PM, Timothy Murphy gayleard@eircom.net wrote:
Gordon Messmer wrote:
On 07/03/2015 03:43 AM, Timothy Murphy wrote:
I've tried this again, and it does not seem to work. Have you actually tried it?
I don't have a CentOS system here that I can reboot readily. And it occurs to me that if I did, I didn't ask if your system boots via BIOS or UEFI.
Thanks for your response. It boots via BIOS, and in fact boots into CentOS-7/KDE on a USB stick (that is how I installed CentOS-7), and into Fedora-21/KDE on a stick.
But it doesn't boot back into the CentOS-7 system that is normally running if I say "sudo grub2-install /dev/sdc" (the USB stick is sdc). It just comes up with the repeated "-", which I take to mean it has found the boot-loader on the USB stick, but has not found the kernel on /dev/sda6.
i think that command is ambiguous because there's four distinct parts to GRUB. The boot.img goes in the MBR (or GPT BIOS Boot partition), which is all the /dev/sdc is telling it; the core.img and the extra modules have to go in a directory on that same device. So you have to tell it where. And in that same directory you need to put a grub.cfg, using grub2-mkconfig. http://www.gnu.org/software/grub/manual/grub.html#Invoking-grub_002dinstall
Such as this example where you have, /dev/sdb1 as ext4 with a boot/ directory on it, and you've mounted it at /mnt
grub-install --boot-directory=/mnt/boot /dev/sdc
Another possibility is using grub2-mkrescue. http://www.gnu.org/software/grub/manual/grub.html#Invoking-grub_002dmkrescue