install Linux on an Intel Mac

install_Linux_on_an_Intel_Mac.txt

install Linux on an Intel Mac

instructions assume the following:
  you are preparing the Linux installer on a Mac running macOS 14.6
    (older versions of macOS may reference some specifics with slightly different naming in Disk Utility, but the logic is the same going back to macOS 10.11)
  for the purposes of this tutorial, Linux = Elementary OS 7.1
    essentially a stripped-down Ubuntu with a much better UI and a separate app store layer that will feel very familiar to those who have used Apple's App Store

how to install Elementary OS 7.1
  https://www.youtube.com/watch?v=31M6XtYDaho
    somewhat annoying music, and really only the first half of the video is required for general install and software update needs
  https://elementary.io/docs/installation#installation
    this has good general info and a different installation video that may be useful

get the ISO install image
  you will need a minimum 8GB USB flash drive
    4GB might work, but 8GB is a sure thing
    the drive will be completely overwritten, so make sure it doesn't have anything on it you want to keep
  go to https://elementary.io
  you can pay however much you like for it, down to $0, and $0 will reveal a download button, which downloads an ISO file

prepare the USB flash drive

  the easiest way to do this is using the Disk Utility app and a command-line utility called 'dd'
  plug in the USB stick
  open the Disk Utility app (in /Applications/Utilities/)
  click the disk's top-level in the left-hand pane
  note 'Partition Map' field: if the target disk is not already partitioned as 'Master Boot Record', erase and re-partition the disk
    right-click the disk's top level in Disk Utility, choose 'Erase', and select
      Name: leave as-is
      Format: MS-DOS (FAT)
      Scheme: Master Boot Record
  once the disk is prepared, note the Device field, e.g. disk3
  unmount the volume, but NOT the disk, from the left-hand pane
    most likely the volume will be an entry under the disk called 'NO NAME' - eject this, but not the parent entry above it
  launch the Terminal app (also in /Applications/Utilities/)
  we use a data transfer utility called 'dd' to write the ISO file's contents to the USB flash drive, e.g.
    dd if=/Users/mc3/Downloads/elementaryos-7.1-stable.20230926rc.iso  of=/dev/disk3 bs=4m
      'if' means input file, so this is the full path to the ISO file downloaded above
      'of' means output file, thus the USB drive (this is where the "disk#" info noted above becomes relevant)
      'bs' means block size, and while it can influence many things, here means how much data is read from the ISO each pass before an attempt to write is made to the USB flash... 4m is a safe value that won't take forever
  become the root user using the command 'sudo su -', then enter your usual macOS password
  enter the dd command, modified as necessary for your system, from the above example, and press Enter
  writing process will take a while, but once completed, you should see a summary of the actions it took
  
install rEFInd EFI bootloader
  this is a more flexible means of managing non-macOS booting, with the alternative being the less friendly and less flexible 'hold down the Option key after the startup chime'
  just the paste the following into your web browser to download the current rEFInd installer
    https://sourceforge.net/projects/refind/files/0.14.2/refind-bin-0.14.2.zip
  uncompress the downloaded file (if it doesn't do so automatically)
  if you like, read the README.txt file inside the resulting folder
  launch the Terminal app (also in /Applications/Utilities/)
  become root user using the command 'sudo su -', then enter your usual macOS password
  run the rEFInd install script (you can just drag and drop 'refind-install' from the Finder window onto the Terminal app's window, and then press Enter in Terminal app)
  if you get an alert about "SIP ENABLED!", use your phone to take a photo of the instructions, then follow those instructions to run the installer from Recovery Mode
    older versions of macOS do not have SIP, which was introduced in macOS 10.11
    SIP background: https://en.wikipedia.org/wiki/System_Integrity_Protection

boot to USB flash installer and follow install steps
  reboot your Mac and choose the Elementary OS installer icon from rEFInd, which will probably be a circular orange icon
  follow the steps as outlined in the video links recommended above