Yesterday I seem to have installed Xubuntu 12.04.3 onto an external HDD (970 gig) and did so with an Acer 1410 (4 gig, 64 bit). I had to use boot-repair-disc afterwards to restore the Acer's ability to boot. The external HDD appears to contain the appropriate files but won't boot on a Windows 7 (HP dv7 6 gig) machine wherein the bios is set to boot from a USB HDD as first choice. That option seems functional because Knoppix 7.2.0 thumb drive boots satisfactorily. At this time, I don't want my w7 computer to be a dual boot. Instead, I'd like to have Xubuntu booted only when the external HDD is connected and start or restart is initiated. Is there a way to install grub only on the external HDD? GUI preferred if possible.
Related, long thread has points of relevance but much that differs from my situation.
In that thread, oldfred wrote:
I would make sure to have an efi partition on external drive, so you can boot from it. But you can install grub2's efi files to either drive(or both, but then will have duplicate entires in UEFI menu). The advantage of having the efi on the external is that then you can boot from that without the internal drive.
I install grub2 everywhere. But sometimes it takes some effort to configure it correctly. And now the new UEFI systems have made it a bit more complex as you have to know if booting in UEFI or BIOS mode. But since installer boots in either mode there are ways to configure both.