直接上操作步骤：
leekwen@leekwen:~# grub-mkpasswd-pbkdf2
Enter password: <<<这里输入你的grub密码
Reenter password: <<<这里输入你的grub密码
Your PBKDF2 is grub.pbkdf2.sha512.10000.BC4D0A450E86EE447561FC822C832xxxxxxxxxxxxx45572D3B4E40500CE
leekwen@leekwen:~# cp /etc/grub.d/00_header /etc/grub.d/00_header.bak
leekwen@leekwen:~# vi /etc/grub.d/00_header
leekwen@leekwen:~# tail -n 6 /etc/grub.d/00_header
### Add those line to set GRUB2 password
cat <<EOF
set superusers="leekwen"
password_pbkdf2 leekwen grub.pbkdf2.sha512.10000.BC4D0A450E86EE447561FC822C832xxxxxxxxxxxxx45572D3B4E40500CE
EOF
### Add end
leekwen@leekwen:/etc/grub.d# update-grub <<运行此命令才可以生效
Generating grub.cfg ...
Found linux image: /boot/vmlinuz-3.11.0-15-generic
Found initrd image: /boot/initrd.img-3.11.0-15-generic
Found memtest86+ image: /memtest86+.bin
done
这样重启后，在启动项时，按e后，就会让你输入：
username:
password:
只有用户名（比如我刚刚设置的用户名为：leekwen）及密码正确后（刚刚用grub-mkpasswd-pbkdf2生成的密码），才可以进入启动项的编辑菜单，启动项这一步倒是安全了，记住，修改00_header后一定要运行“update-grub”命令，这样才能生效！