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A little while ago I switched my late 2015 Macbook Air to Ubuntu (not dual boot) because I needed a linux computer for work. I overwrote the existing os because it was taking up a massive amount of the storage space and i said "I can always just use a bootable usb to switch back if i dont like Ubuntu". This might have been stupid, but it made sense at the time. There have been issues with Ubuntu and I like it less in general, and no longer need it for work, so I am trying to switch back to mac os. I tried booting the computer in Internet Recovery mode by holding Command + R and selected the Reinstall OSX option and went through the steps until I got to the part where you select the disk to install it on. Normally I think there would be an option called Macintosh HD there, but it is currently empty, as you can see in the attached image.
I also should mention that I have a bootable usb with High Sierra on it that I made with my other computer, and when I plug it in, and boot the computer while holding the option key and follow the necessary steps I get the same problem, where the hard drive is not visible, and only the bootable usb is shown. Is it possible that when I installed Ubuntu I overwrote the Macintosh HD? Is there any hope of getting back to mac os? Any help is appreciated.

Note: My Mac has a single internal SSD.

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  • When you get to Recovery, first thing you will need to do is reformat the HD, GUID/HFS+ from Disk Utilities. – Tetsujin Mar 5 '18 at 20:01
  • Okay, I have booted again with Command + R and opened the disk utility. I see an one Internal drive called APPLE SSD SM0128G Media. Is that the one I need to be reformatting? And how do I do this? Sorry, I just don't want to mess it up and go from bad to worse. – Riley Bolen Mar 5 '18 at 20:19
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Yes, when you installed Ubuntu, you overwrote the partition named Macintosh HD. You will need to recreate this partition before installing macOS (OS X).

You can use the Disk Utility application to erase your drive. For name, use Macintosh HD. For the format, use either Mac OS Extended (Journaled) or Mac OS Extended (Journaled, Encrypted).

Sometimes when the previous operating system was Linux, this can fail. If so, perform the steps given below.

  1. From the menu bar, select Utilities→Terminal.
  2. In the Terminal windows enter the following commands.

    diskutil  unmountdisk  disk0
    diskutil  erasedisk  jhfs+  "Macintosh HD"  GPT  disk0
    
  3. Quit the Terminal application.

  4. If you want encryption, use the Disk Utility application to erase the drive again.

  5. Install macOS (OS X).

Note: If you install or upgrade to High Sierra and your internal drive is a SSD, then this drive will probably to converted to use the new Apple File System (APFS) format.

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  • Thank you, this appears to have worked! Just out of curiosity, do you know why this is required? Did Ubuntu reformat the hard drive when it was installed? – Riley Bolen Mar 5 '18 at 20:34
  • There are may ways to install Ubuntu, all require creating new formatted partitions. It is even possible that a working macOS (OS X) is still exists on your Mac. At this point you, it would be best to remove all partitions, create new partitions, format the partitions and install a clean copy of macOS (OS X). – David Anderson Mar 5 '18 at 20:35
  • Thanks, I'll keep that in mind if i run into any issues with this install. When I installed Ubuntu I just used a bootable usb, and chose the overwrite existing os option. Wouldn't it only preserve the old os if I had tried to do a dual boot? – Riley Bolen Mar 5 '18 at 20:40
  • My mistake. You did state you overwrote the previous operating system when you installed Ubuntu. – David Anderson Mar 5 '18 at 20:48

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