双系统环境下,重装win7，恢复ubuntu的办法

我的电脑配置:

bob@bob-ThinkPad:~$ cat /etc/lsb-release 
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=13.10
DISTRIB_CODENAME=saucy
DISTRIB_DESCRIPTION="Ubuntu 13.10"

+win7

利用livecd，重启，进入livecd环境

sudo fdisk -l : to verify the sda index,to choose the id==83

sudo -i

mount /dev/sda8 /mnt

grub-install --root-directory=/mnt/ /dev/sda

then, restart the computer

sudo update-grub

sudo grub-install /dev/sda