Hi David, yes, that is what I thought, would be working. But sadly did not.
I expected, after using update-grub, that os-prober would detect both partitions with the menu.lst or grub.cfg inside and create two entries in the boot menu. However, this did not work, only one (the last installation, which was kali), was seen. Maybe I did something wrong! I had had Windows-7 and Debian on the hardddrive. Then I deleted the Windows-7 partition (good choice, eh?) and installed kali on this partition. With installing grub during the installation process, I expected grub to see both, kali and debian. But, it only recognized kali. So my idea was, to edit kali's grub.cfg manually, so that I got two entries, but did not succeed (becauuse I did not know, how exactly to do). Meanwhile I am using the whole harddrive for kali, because I discovered that the partition was to small for kali (34GB, but I needed 50GB). But I think, this problem will appear in some time, when I am buying a bigger harddrive, where I intend to put several different operating systems on one harddrive. Thanks for the feedback, and all your help. If I got a solution, I will tell you. Best regards Hans > If you want to boot A, just select it from the menu presented by B's > grub. > > When you boot and run A, you can update-grub¹ and that will scan > and see both systems, writing A's grub.cfg with A as the default > system to boot /in its grub.cfg/. However, A's grub.cfg will never > be consulted, because the MBR points to B's grub.cfg. (Think of > B as the "master system".) > > (Only if you run grub-install on system A will the MBR be overwritten > so that it points to A's grub.cfg, and from then on, booting would > use A's grub.cfg.)
