Win7, Ubuntu dual system appears the "unknown filesystem" prompt and the "Grub Rescue" command line, modify the boot-initiated • method.

The Acer bought a notebook, with the original Win7 family version of the system, later installed Win7 flagship version, and then play Ubuntu, notebook to bring 3 systems. In order to expand the flagship version of the system disk space, the original system Acer disk to the grid, merged into the flagship version of the system disk. Not thinking too much, direct formatting. Who knows, after reboot, appear Error:unknown filesystem, also have grub rescue, prompt repair grub. Startled and prepared to reload. But look at the hint, thinking that you should modify the startup items on it, not serious to the point of reloading.

So, on the internet search, http://askubuntu.com/questions/142300/how-to-fix-error-unknown-filesystem-grub-rescue to the post listed a number of solutions, I used the following Warrior's approach. First of all, find out which disk Unbuntu installed, you can use the LS command to identify, such as LS (HD0,MSDOS6)/boot/grub, if the unknown filesystem indicate that the disk is not unbuntu the disk. The full path appears, and that is the disk that we are looking for to install Unbuntu. Then follow the instructions below to set root and prefix, then insmod normal, and then normal. Then reboot and remember to go into the Unbuntu to update grub, directly open the Unbuntu command line, sudo update-grub, and then sudo grub-install/dev/sda. Restart to enter the Win7.

However, because my Acer disk is merged into the flagship version of the system disk, originally installed in the system disk software or data, you can return to the path could not find the situation, it is necessary to choose the flushing installation.

These steps solved the issue. I am having Windows 7 & Ubuntu 10.04. After running steps on the below I don ' t need to run this every time and able to boot OSs normally:set root= (hd0,6) set prefix= (hd0,6)/boot/grub insmod normal normal sudo update-grub  (Run this in terminal after getting into Ubu NTU) sudo grub-install/dev/sda  (Run this in terminal over getting into Ubuntu)