Ubuntu – Modified Mac bootloader after installing Ubuntu on external HDD

bootgrub2hard drivemac

I wanted to install Ubuntu in an external HDD to boot it from my Macbook Pro.
After following Coljac's response at:
How to boot Ubuntu on a mac from external USB storage?

I've found that my computer no longer boots by default on MacOS X, but instead shows a GRUB prompt. I can still access the original boot menu if I press Alt after powering the computer on, but I would like the boot to behave as it used to.

How may I get back to that configuration without breaking my Ubuntu boot on the external HDD?

Best Answer

I actually found how to fix this and recover the original MacOS X boot menu and default boot to MacOS X.

It was originally posted as an anser by SamC in the same question I referenced before. A summary as follows:

Run diskutil to find the volume identifier for your EFI partition: diskutil list. Expect an identifier like /dev/disk0s1.
Create a mount point for the EFI partition, for example: sudo mkdir /Volumes/EFI
Mount the EFI partition in the created mount point: sudo mount -t msdos /dev/disk0s1 /Volumes/EFI
Delete the Ubuntu and refind folders and their contents: sudo rm -r /Volumes/EFI/Ubuntu /Volumes/EFI/refind

Restarting should show everything back to normal.

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Ubuntu – Install Ubuntu on external disk ,Mac OS

I've just created a similar configuration on my Mac Mini (OS X Mavericks and Windows 7 on internal SSD, Ubuntu on external drive). Here's what you'll have to do:

create back up images of the OS X and Windows partition (optional but strongly recommended)
create a bootable USB stick with the ubuntu installer
holding down the option key, boot from the ubuntu installer stick
install ubuntu to the external hard disk
On reboot (I had to force the shutdown by pressing and holding the power button, as it seemed to have stalled some time after clicking reboot), hold down the option key to boot into OS X
download and install Refind boot manager
edit the refind configuration file /efi/refind/refind.conf (the line you're looking for starts with scanfor) and make sure hdbios is included in the list
on reboot, you should now be greeted with a menu containing a ubuntu, Mac and Windows logo (you can press esc to refresh the list, as external drives can take some time to show up; you can configure refind to pause befaure showing hte menu)

Hope this helps.

Greg.

Ubuntu – Ubuntu booting in mac

Below is the sequence of steps needed to finish installing Ubuntu on a Mac. I assume you installed Ubuntu to use EFI booting.

Boot to Ubuntu live.
From the Desktop, press the control+option+T keys to open a Terminal window.
Enter the command shown below.
```
sudo  fdisk  -l  /dev/sda
```
Below is the output I saw from entering this command.

Note: For a better view, click on the image or open the image in a new window.
From the output of the sudo fdisk -l /dev/sda command, determine the device for the EFI System partition. For me, this was /dev/sda1. If you determine a different device, make the appropriate substitutions.

Enter the commands given below to make Ubuntu appear in the Startup Manager.

sudo  bash
mkdir  efi
mount  /dev/sda1  efi
cd  efi/EFI
mkdir  BOOT
cp  ubuntu/grubx64.efi  BOOT/bootx64.efi
cd  ~
umount  efi
rmdir  efi
exit
exit

Shutdown Ubuntu live.
Startup the Mac and immediately hold down the option key until the Startup Manager icons appear.
Click on the hard disk icon labeled "EFI Boot". Next, while holding down the control key, click on the circular arrow below this icon.

You are finished. Your Mac will now automatically boot to Ubuntu on startup and restart.

Best Answer

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Ubuntu – Install Ubuntu on external disk ,Mac OS

Ubuntu – Ubuntu booting in mac

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