There exists quite a bit of controversy today over various ways and means of installing Linux flavors on high quality but low compatibility Apple hardware, and it pleases me to say that i have apparently discovered the easiest and most outrageous means of them all for doing it!

. . . Never seen even a hint of this before, and although it has been accomplished on X86 hardware designed for Windows, as far as i know no one has ever even skipped lightly over this simple, new path to Gretchen Green Apple. And it works!

All it takes is maybe 30 minutes* of minor tedium and you're done, provided you buy a new laptop hard drive. Otherwise it takes a little longer.

You'll need a set of micro screwdrivers, including tiny Phillips heads and a kit for allowing external HD connections. If you Google "USB universal drive adapter" you should get multiple hits and you can buy from whoever has the best price. I've been paying a little under $40 lately.

Now: begin by removing the underbelly of any late model X-86 laptop (maybe your old Windows laptop?) and pull the battery, crack the lid and press the power button (to wick off any residual electricity), remove the HD (if you're planning to make the MacBook Pro your main machine); and set the old laptop aside in the disassembled state.

If it's someone else's laptop and they are allowing you to use it, you'll either want to buy a new HD that will work in both the Mac and the borrowed machine or wipe the Mac HD and use it, pulling the latter out of the MacBook Pro (going under the same drill as above, except that you won't be able to remove the battery; you will have to c-a-r-e-f-u-l-l-y lift up the little connector that attaches it to the mobo); press the power button afterwards to wick the circuit, finally removing the HD from the Mac.

Once you accomplish the latter plz connect the Mac HD to a remote Firewire or USB remote kit and wipe it to your level of satisfaction. Or did you buy the new HD?

You can try using Bleachbit 2.0 on another computer running Ubuntu by setting the remote disk as the target directory, but not merely for a free space wipe; you want to completely remove the old Apple file system and everything that pertains to macOS or OSX. Bleachbit should work for disk wipes but i've never done it.

Or, if you have access to another Mac you can run the wipe using Apple Disk Utility. I like it best.

At any rate, there's nothing to any of the above that requires high-tech knowledge, provided you've been using computers for a while and are beyond the newby stage.

After the Mac HD has been bare-metal wiped (or, if you don't care about high security, just run a quick erase), which in the former case will take at least several hours* (yep; the 30 minutes to completion just flew out the window), install it on the friend's laptop by carefully back-stepping the disassembly process. . . and run an installation of Ubuntu 18.04 LTS on the newly wiped HD, either from thumb drive or DVD. No point in restoring the belly cover now.

Absolutely, positively DON'T try to run a direct Ubuntu install on the Mac!

Despite the verbosity of this summation and its seeming complexity the entire operation is a garden variety cake walk that virtually anyone with a few years' experience can accomplish.

While running the Ubuntu 18.04 installation on the X-86 laptop you will have the standard options for going heavy or lite; your choice.

After the installation completes run updates (it's best to use terminal and although some Ubuntu experts may frown on it i nonetheless do it like this: sudo apt update -m && sudo apt dist-upgrade && sudo apt full-upgrade && sudo apt install -f) - All in one swell foop. Saves time.

Done? (You didn't actually replace the belly cover on that laptop, did you?). . . Turn it upside down and again remove the battery.

Then, crack the lid and hit the power button a couple hundred times to wick off electricity (kidding; 3 or 4 times is sufficient); remove the newly installed HD; replace the original HD with your friend's Ubuntu OS intact and button everything up the way it was when he handed it to you.

As a peripheral task you may consider erasing your friend's RAM modules while you have at the innards by removing the latter while the battery is out. Run a pencil eraser over both sides of the pins, gently brushing them clean of rubber shavings afterwards with an old wire brush i mean tooth brush and carefully replace them, insuring that they're pressed completely back into the risers as far as they will go. B4 you do the latter look for any dust bunnies in the riser slots and give 'um a good blast of hot air.

If you are the saintly type you could even erase the pins on your friend's video card; just be careful with the little connector. A tiny needle-nose pliers and gentle touch will go far.

Okay: You're ready for the acid test.

You 1) reinstall the newly installed Ubuntu 18.04 LTS HD on the Mac; 2) it would be folly to button-up B4 erasing both RAM and GPU; amazing how much difference that makes for error-free computing - your call; dust bunnies all gone? 3) when you're done reattach the tiny battery connector LAST (but watch out! It's dinky); replace the tiny screws on the undercover and upend the Mac; 4) connect the power supply and press the power button.

The Mac should boot initially to the platinum screen and remain there for about 30 - 40 seconds. Don't get antsy.

Then, you'll (hopefully) be greeted by a purple screen, the standard you're accustomed to seeing under normal Ubuntu usage. Or, you can try pressing the option (alt) key and see if it hastens your arrival at login. Again, your call.

Although Ubuntu 18.04 seems a rather slow booter it's not long on my 2011 MacBook Pro B4 the login screen appears; should function similarly with yours; i'd label it as normal and after entering your decryption PW and with Automatic Login enabled you're soon greeted with the familiar Ubuntu desktop.

The best time to decide if you want Automatic login of course is during installation on the X-86 machine.

To encapsulate: Install Ubuntu 18.04 LTS on an X-86 hardware-based machine and transfer the HD over to your MacBook Pro.

I sincerely hope this works for you.