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I had 4 partitions on my HDD, C, D and 2 reserved, I had GPT style partition table.

To install Ubuntu I shrank D from 338 to 278 GB, started installing Ubuntu on remaining approx 60 GB, from which I used 59.7 GB for installation and the rest for Reserve boot bios type what it wants to install GRUB.

All installation went successfully but now it's directly booting into Ubuntu 20.04, not showing the GRUB menu to make selection between installed OSes.

How can I fix it?

Zanna
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Oralover
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2 Answers2

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Edit your /etc/default/grub as such.
Edit or replace these lines;
GRUB_DEFAULT=0
#GRUB_DEFAULT=saved
#GRUB_SAVEDEFAULT=true
#GRUB_TIMEOUT_STYLE=hidden
GRUB_TIMEOUT_STYLE=menu
GRUB_TIMEOUT=10

Commit the changes then don't forget to... sudo update-grub then reboot.

darth_epoxy
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  • hi, thanks a lot for prompt response, in addition to above mentioned question, i checked bios setup, its boot priority was Legacy First, i change to UEFI Fiirst then it boots into windows but still not showing grub. – Oralover Sep 26 '20 at 04:12
  • hi @darth_epoxy, modified /etc/default/grub as instructed and updated grub, reboot, its now showing grub menu but windows 10 not appeared... is this because of windows 10 is UEFI model ? how i can resolve it? is there anything to set during ubuntu installation so i can re-install it because it is fresh, nothing added/updated except grub as per your instruction. regards – Oralover Sep 26 '20 at 05:17
  • UEFI replaced BIOS some years ago so it is not related to windoze or linux rather the actual PC. Grub or Grub2 is universal as it's name implies so grub can be used to boot and load almost every OS so you should not have a problem getting your windows10 partition to show up However I am not your man for this so hopefully a relevant expert might respond. – darth_epoxy Sep 26 '20 at 05:48
  • isn't it possible to solve this problem? still i am unable to have Win'10 in grub menu. – Oralover Oct 01 '20 at 13:11
  • Go here https://askubuntu.com/questions/661947/add-windows-10-to-grub-os-list and try the anwer that starts with Sometimes os-prober is wrong. and give us all some feedback. – darth_epoxy Oct 02 '20 at 08:28
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In Ubuntu 20.04.2 with MATE desktop, GRUB_TERMINAL=console was what helped reveal the grub boot menu. GRUB_TIMEOUT_STYLE was set to menu but Ubuntu or MATE desktop graphical boot menu was hiding the grub menu.

So these in /etc/default/grub:

GRUB_TIMEOUT=3
GRUB_TIMEOUT_STYLE=menu
GRUB_TERMINAL=console

As always, don't forget sudo update-grub.

If Windows 10 doesn't show up in grub menu, os-prober auto-detected my windows install and then update-grub brought it back. Shew, back to dual-boot. Worked just like you'd want.

Marc Compere
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