I have a Macbook Pro 8,1 (early 2011 model). My goal is to have Ubuntu installed onto a USB stick what I can plug into any Macbook / iMac (also potentially any pc) and use Ubuntu anywhere.
Here is what I tried so far:
I followed the official instructions to create a bootable usb stick with the ubuntu live image amd64 14-04. It worked perfectly for me, I was able to boot up from the USB stick by holding down the Option key while turning on the Macbook and selecting the EFI in the boot menu. However, it did not save any of the modifications I made. Since I need to install a package to make WIFI work, it is necessary to save the changes.
After this I created a bootable USB stick with "Startup Disk Creator" on an existing Linux machine, selecting 1GB as a reserved extra space. This was also booted up perfectly (holding down the option key, as above), however I did not see the extra partition mounted anywhere, and indeed it lost all modifications when I restarted.
After this I installed Ubuntu to an other USB stick from the live ubuntu booted from the first USB stick. The new Ubuntu installation works. Set noatime and installed the Wifi driver without issues. There is only one problem: when I start up the Macbook, it starts grub. If the USB stick is plugged in, the grub shows Ubuntu as a boot option. When the USB stick is not plugged in, then I only get a grub prompt where I can enter grub options to boot up the OS.
When I installed Ubuntu I'm sure I selected the usb stick as a target for grub, so I don't know why did it modify anything on the computer's build-in harddrive.
Luckily I can start OSX by holding down the Option key and select the built-in harddrive. But the USB stick does not appear in Mac's boot menu, so I can only start Ubuntu with grub, also cannot boot it up on other Macbooks.
A) How can I make the second USB stick similar to the Live Ubuntu USB stick, so it appears in the Macbook's boot menu as an EFI drive?
B) How can I remove grub from the built-in disk, so I can boot up my Macbook normally?