Unable to boot into Ubuntu after installing fedora 15
 

hi friends, I am new to linux and started using ubuntu and was so impressed with it that I decided to try out other distros as well. So, I installed fedora 15 into another partition and made ubuntu as default. Now fedora works fine but ubuntu doesnt.It gives error 13- unknown file system. What should I do to retain Ubuntu?

Thanks

The correct way involves running update-grub, but it may not work correctly. but the way I've resolved similar problems is to plug in a spare USB flashdrive and install Ubuntu to it. The Ubuntu install will automatically detect other operating systems and add them to grub. (make sure you set the installer to boot from the main hard drive.) Then I remove the flash drive, boot into Ubuntu (the one on the hard drive since the flash drive is no longer attached) and, from a command line I run update-grub. (you can try running update-grub from Fedora before trying this and see if that works btw.)

Just as a point of interest. It's usually recommended, when multi-booting, to always install Ubuntu last as it's install is much better at detecting other OS's than most distros.

Fedora usually detects windows but doesn't usually detect other Linux distros. See posts about this all the time. Another way is to use this entry in your Fedora /boot/grub/grub.conf file:



You may need the savedefault and boot lines. If it doesn't work with the above entry, try removing the hash marks (#) at the beginning of those lines. You will also need to change the root line to reflect the partition Ubuntu is actually on. Fedora is grub legacy so partitions begin counting at zero. You will need the core.img file but if you were previously booting Ubuntu, it will be there.

Thanks a ton. This did work. All the while I didn't know that grub should be installed on main harddrive and not on partitions.
I installed ubuntu once more onto another empty partition and its grub onto main hard drive. Now, all OS are listed in GRUB menu.