Add Windows boot entries after installing Ubuntu?

Question

I have Windows 7 on its own bootable hard drive, Windows 8 on its own bootable hard drive and Ubuntu on its own bootable hard drive. I'm using the BIOS to manually select on which hard drive to boot. I would like to combine them all in one boot manager/Grub. I was thinking that Ubuntu would be best. Is there a way to manually add the Windows drives to Grub?

Answer 1

On current Debian, and therefore most likely also *buntu, installing 'os-prober' (if not already installed) will help the grub updater auto-detect the other operating systems, and add entries for them.

So you could:

• Configure your Firmware (BIOS/UEFI) to boot from the Ubuntu drive
• apt-get install os-prober just to be sure.
• update-grub and verify seeing the other OSs in the list.
• Reboot and choose.

Answer 2

choose ubuntu as boot disk, you can change ubunutu Grub at

sudo gedit /boot/grub/grub.cfg

This is my grub.cfg.

update/add this part to recognize windows, note that change location to match your device (/dev/sda1)

### END /etc/grub.d/20_memtest86+ ###

### BEGIN /etc/grub.d/30_os-prober ###
menuentry "Windows 7 (loader) (on /dev/sda1)" --class windows --class os {
        insmod part_msdos
        insmod ntfs
        set root='(hd0,msdos1)'
        search --no-floppy --fs-uuid --set=root 6CDA3B7DDA3B431E
        chainloader +1
}
menuentry "Windows Recovery Environment (loader) (on /dev/sda4)" --class windows --class os {
        insmod part_msdos
        insmod ntfs
        set root='(hd0,msdos4)'
        search --no-floppy --fs-uuid --set=root B07227D77227A0D8
        drivemap -s (hd0) ${root}
        chainloader +1
}
### END /etc/grub.d/30_os-prober ###

after edit your grub, save it

sudo update-grub

then restart ubuntu

Note: there also a GUI app called grub-customizer that you can try if you want. this is the reference http://www.howtogeek.com/howto/43471/how-to-configure-the-linux-grub2-boot-menu-the-easy-way/

Hope this help