boot ubuntu 16.04into text mode（ubuntu 16.04启动进入命令行）
步骤如下：
sudo vi /etc/default/grub
Comment the line GRUB_CMDLINE_LINUX_DEFAULT=”quiet”, by adding #at the beginning
Change GRUB_CMDLINE_LINUX=”" to GRUB_CMDLINE_LINUX=”text”
Uncomment this line #GRUB_TERMINAL=console, by removing the # at the beginning
sudo update-grub
sudo systemctl set-default multi-user.target
