“ error: file not found.” followed by “grub rescue> _ ” 解决

安装ubuntu系统，或者在使用过程中重启，可能出现grub rescue issue，通过百度找到下面这个链接：

http://blog.163.com/l1_jun/blog/static/143863882013101234922566/

实验发现没效果，但作为普及相关知识，可以大概了解一下。

百度在这方面一直不给力，而google最近又被和谐的厉害，最后借助 ask.com 找到下面办法：

Use Boot Repair to fix your bootloader.

1. Boot Ubuntu from a LiveCD or Live USB  （可以通过 ubuntu usb 启动盘）
2. Connect to the internet

3. Open a terminal, and add the Boot Repair PPA

   sudo add-apt-repository ppa:yannubuntu/boot-repair && sudo apt-get update

4. Install Boot Repair

   sudo apt-get install -y boot-repair && (boot-repair &)

5. Launch and use, see https://help.ubuntu.com/community/Boot-Repair#Using_Boot-Repair for more details

  完整命令如下：

sudo add-apt-repository ppa:yannubuntu/boot-repair
sudo sed 's/trusty/saucy/g' -i /etc/apt/sources.list.d/yannubuntu-boot-repair-trusty.list
sudo apt-get update
sudo apt-get install -y boot-repair && (boot-repair &)

Advanced options

Warning: the default settings are the ones used by the "Recommended Repair". Changing them may worsen your problem. Don't modify them before creating a BootInfo URL, and asking advice on this thread.