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urs avatar Ubuntu

How can I access grub and boot from USB on an iMac?

cn flag
urs

I can't boot from USB and I can't access grub!

Here's what I tried so far:

  • Holding shift, ESC and Alt on boot.
  • Changing the timeout in grub from 0 to 5
  • Changing grub=hidden to grub=menu

But I just can't get into grub or boot from a USB.

            .-/+oossssoo+/-.               urs@urs-iMac 
        `:+ssssssssssssssssss+:`           ------------ 
      -+ssssssssssssssssssyyssss+-         OS: Ubuntu 21.10 x86_64 
    .ossssssssssssssssssdMMMNysssso.       Host: iMac12,2 1.0 
   /ssssssssssshdmmNNmmyNMMMMhssssss/      Kernel: 5.13.0-21-generic 
  +ssssssssshmydMMMMMMMNddddyssssssss+     Uptime: 8 mins 
 /sssssssshNMMMyhhyyyyhmNMMMNhssssssss/    Packages: 2293 (dpkg), 21 (snap) 
.ssssssssdMMMNhsssssssssshNMMMdssssssss.   Shell: bash 5.1.8 
+sssshhhyNMMNyssssssssssssyNMMMysssssss+   Resolution: 2560x1440 
ossyNMMMNyMMhsssssssssssssshmmmhssssssso   DE: GNOME 40.5 
ossyNMMMNyMMhsssssssssssssshmmmhssssssso   WM: Mutter 
+sssshhhyNMMNyssssssssssssyNMMMysssssss+   WM Theme: Adwaita 
.ssssssssdMMMNhsssssssssshNMMMdssssssss.   Theme: Yaru-dark [GTK2/3] 
 /sssssssshNMMMyhhyyyyhdNMMMNhssssssss/    Icons: Yaru [GTK2/3] 
  +sssssssssdmydMMMMMMMMddddyssssssss+     Terminal: gnome-terminal 
   /ssssssssssshdmNNNNmyNMMMMhssssss/      CPU: Intel i7-2600 (8) @ 3.800GHz 
    .ossssssssssssssssssdMMMNysssso.       GPU: AMD ATI Radeon HD 6970M/6990M 
      -+sssssssssssssssssyyyssss+-         GPU: Intel 2nd Generation Core Proce 
        `:+ssssssssssssssssss+:`           Memory: 1462MiB / 11948MiB 
            .-/+oossssoo+/-.
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avatar Ubuntu
gb flag
AaronTheIssueGuy

You can enter the boot device selection on IMacs by holding alt. I am using a Mac and in my experience spamming Alt during boot works better.

You can also try to spam esc during boot to enter GRUB. If you end up in a commandline type exit and try to immediately press esc again.

Something else that has caused me issues before is an international keyboard. During boot your keypresses will be interpreted as if you are typing on a qwerty layout.

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urs avatar
cn flag
urs
Thank you - but still none of the above works! Now I've got the problem that it stopped booting altogether and there's nothing I can do about it. Can't enter GRUB and it doesn't boot from USB :-(
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