Installing Windows 10 on partition removed Ubuntu option for UEFI
Solution 1:
When you installed Windows it replaced the the Grub (Linux Boot Manager) with Windows Boot Manager. The Windows Boot Manager doesn't see Ubuntu. You'll have to replace the Windows Boot Manager with Grub, which can see both Windows and Linux and will give you both as a boot option.
You can reinstall Grub with these steps:
$ sudo mount /dev/sdX# /mnt$ for i in /sys /proc /run /dev; do sudo mount --bind "$i" "/mnt/$i"; done$ sudo mount /dev/sdY# /mnt/boot/efi$ sudo chroot /mnt# grub-install /dev/sdZ# update-grub# exit$ for i in /sys /proc /run /dev; do sudo umount "/mnt/$i"; done$ sudo umount /mnt/boot/efi$ exit
- Steps #3 and #9:
They are for a UEFI mode setup. It doesn't hurt to perform those steps regardless of the mode. If you don't have the EFI partition, you'll get an error which can be ignored. Continue to the other steps (which shouldn't give errors and should not be ignored). If you do have the EFI partition, but you're installing Grub from a Legacy boot, the Grub Install will ignore the EFI partition.
- The variables:
/dev/sdX# - the partition that has your Ubuntu Installed (ext4). /dev/sdY# - the EFI System Partition. /dev/sdZ - the drive you will be booting from (/dev/sda, /dev/sdb, etc.).
You can identify your drives and partitions with this command:
sudo lsblk -o name,mountpoint,label,size,fstype,uuid;sudo parted -l
After you have completed those steps, you will now see Ubuntu as a boot option. Boot to it and you'll have the both Ubuntu and Windows as a menu choice.
Notice:
The $ and the # part of the command-lines are the terminal prompts. It's important to show that the $ prompt is a normal user, requiring sudo to elevate the command. The # prompt which happens after chroot is a terminal logged in as root. The sudo prefix isn't required. While, for security, it's discouraged, some people always work under a # prompt by executing sudo su - before they start work. The $ prompt and sudo is the official Ubuntu recommended method.