Booting Ubuntu from usb on a Mac

Question

I have a Macbook pro (late 2009) running OSX 10.6.8. I want to partition a flash drive and install my Ubuntu iso image onto it. Then I want to boot up from it by (restarting my computer and) holding down the option key.

How could I:

1. Install Ubuntu on the flash drive?
2. Get OSX to see the drive when booting up?

P.S. I tried following This link but it is for Mountain Lion, not Snow Leopard (which is what I have)

Answer 1

The main difficulty here is that Macs use UEFI instead of BIOS. So, according to this page, the following steps should work (I have not tried this myself as I do not have a mac):

1. Get the ISO-2-USB EFI-Booter for Mac 0.01 beta and a recent version of Ubuntu Desktop Edition 64bit.

2. Format a USB drive to provide a single FAT32 partition featuring MBR.

3. Create the following directories on your USB drive: /efi and /efi/boot

4. Copy the bootX64.efi from “ISO-2-USB EFI-Booter for Mac 0.01 beta” into /efi/boot on your USB Drive.

5. Copy the Ubuntu image into /efi/boot/ on the USB Drive, too and rename it to “boot.iso”.

6. You should have 2 files on your USB drive now: bootX64.efi and boot.iso – both in /efi/boot.

7. You’re ready to reboot: During the startup of your Mac hold Alt/Option. You should see “EFI Boot” which has a nice little USB Drive Symbol on it in the appearing boot menu. Boot from your USB Drive by clicking on the little arrow below it.

   Good Luck!

   Ubuntu should be booting now…

Answer 2

You need an EFI bootable USB stick, no matter what distribution you plan to use. For example Porteus distribution offers it out of the box. So all you need to do is following:

1. Go to Porteus Download section and select 64 bit varian and EFI support; rest can be default.
2. Download your ISO image.
3. Copy the content of the image to your USB stick.
4. Run the installer in /boot directory on your USB stick - this will make the stick EFI bootable.

That's it! It works, tested on MacBook Pro 15" Retina.