sudo update-grub

user@notebook:~ > sudo update-grub
[sudo] password for user:
Generating grub configuration file ...
Found linux image: /boot/vmlinuz-3.13.0-24-generic
Found initrd image: /boot/initrd.img-3.13.0-24-generic
Found memtest86+ image: /boot/memtest86+.elf
Found memtest86+ image: /boot/memtest86+.bin
  No volume groups found
Found Windows 7 (loader) on /dev/sda1
Found Windows Recovery Environment (loader) on /dev/sda2
Found Windows Recovery Environment (loader) on /dev/sda4
Found Ubuntu 14.04.1 LTS (14.04) on /dev/sda6
done
user@notebook:~ >