I bought a Apple imac 27" in December 2013. It's been a great computer with no issues, until.. Apple decided to not upgrade the OS (OSX) any longer. The last upgrade of the OS also seems to be the slowest by far. Whether that is intentional or not I will let you decide. It now takes a long time to launch anything. All you get is a spinning wheel for clicking almost anything. It has become unusable. I ran tests on the hardware and it passed with no issues. Soooo, I decided the issue is it needs a new OS. I could load windows on it since it has an intel processor but my experience with Windows 11 has been less than desirable. Therefore there is only one other choice, install Linux on it.
I decided to put Ubuntu LTS on it. LTS stands for long term support and they keep it updated for a longer time without forcing an upgrade. Its tricky to put linux on an Apple computer as it doesn't have a normal bios similar to a PC. I read back through my post on here when I first got the iMac and loaded linux on it. I thought would be a similar process but everything changes with time and software.
Since iMac uses no bios you have to download a boot manager. In the past I used Refit...but its no longer supported. I found a new boot manager called rEFInd After download, to install from a terminal on OSX you have to reboot into recovery mode by holding Command + R when you hear the bong sound during boot up. Then you select Terminal from Utilities pulldown menu. To change to the Downloads folder, you have to type cd /Volumes/Mac/Users/(user name)/Downloads. Once there I changed to the rEFInd folder and ran the install script. This installed the boot loader. After a reboot it displayed a menu with choices of what you want to boot.
The next thing to do is free up space to install the new OS. I used the apple disk utility to resize the OSX partition to create a new apple partition of 250GB for Ubuntu OS. After downloading Ubuntu and copying the .iso to a usb stick, I was ready to boot into Ubuntu and install it. Booting into rEFInd now showed my usb stick with Ubuntu as an option. I selected it and booted into Ubuntu.
I installed Ubuntu by doing a custom partitioning. Make sure to not delete sda1 or sda2 apple partitions. Remove the new apple partition made earlier. Create an sda3 root and sda4 swap (8GB) and make sure they are formatted. Install Ubuntu as normal. After install and reboot my imac booted into Ubuntu automatically without allowing any choice of what OS to boot, not what I had wanted.
I realized that Ubuntu had skipped the rEFInd boot loader by installing a new grub entry into my EFI partition and changing the priority of what to boot. The next step is to reset the boot priority of the boot loaders. This all sounds a bit complicated and it's way more complicated than it needs to be due to apples insistence of being so proprietary. Anyway, I was glad it was pretty easy to set the boot order back to what I wanted. Boot into Ubuntu and open a terminal and type "sudo efibootmgr" This shows the order of what is booted.
By typing "sudo efibootmgr -o FFFF,0080,0001" you can change the order of the boot OS. I changed it to rEFInd first, OSX second, and Ubuntu third. Did another reboot and it booted to rEFInd and I selected Ubuntu. Ubuntu booted and everything worked find. Did a software update and configured some apps and then rebooted to make sure OSX was still booting fine which it does (even though I may never use it again, it has some good tools).
The thing I learned from this exercise is that Ubuntu is fast on this older iMac. Whereas OSX is super slow. This confirmed what I first thought, that its not the hardware that suddenly got slow but something is slowing down the hardware. All i can say is Long live Linux as it's the only thing saving us from these companies that want us upgrading hardware every few years contributing to landfill waste and global climate issues, which they claim they are against. Hint: It's all words, they really only care about money. Otherwise they wouldnt make you upgrade hardware unnecessarily and make phones where you can't even change the battery. I still have two ipads v1 that work perfectly from a hardware perspective but Apple stopped updating iOS on them years ago so its impossible to install any new apps on them. I wish companies would quit obsoleting their products on purpose and let the natural change happen if hardware get too slow, or obsoleted due to ports changing or other needed reasons.
