Ubuntu

Grub Default Boot OS Numbering

Asked by tomdean

I am attempting to select the default boot by editing /etc/default/grub. The machine is remote.

Looking at /boot/grub/grub.cfg, I think the default I want is
  'Ubuntu, with Linux 4.19.240-rt108'
I think it is numbered "1>7"

In /etc/default/grub, I set
GRUB_DEFAULT="1>7"
then,
sudo update-grub

The first item is what I think the menu entry items are. Are these numbers correct?
From /boot/grub/grub.cfg

0 menuentry 'Ubuntu'
  linux /boot/vmlinuz-5.13.0-41-lowlatency

1 submenu 'Advanced options

1>0 menuentry 'Ubuntu, with Linux 5.13.0-41-lowlatency (recovery mode)'
  linux /boot/vmlinuz-5.13.0-41-lowlatency

1>1 menuentry 'Ubuntu, with Linux 5.13.0-41-generic'
  linux /boot/vmlinuz-5.13.0-41-generic

1>2 menuentry 'Ubuntu, with Linux 5.13.0-41-generic (recovery mode)'
  linux /boot/vmlinuz-5.13.0-41-generic

1>3 menuentry 'Ubuntu, with Linux 5.13.0-40-lowlatency'
  linux /boot/vmlinuz-5.13.0-40-lowlatency

1>4 menuentry 'Ubuntu, with Linux 5.13.0-40-lowlatency (recovery mode)'
  linux /boot/vmlinuz-5.13.0-40-lowlatency

1>5 menuentry 'Ubuntu, with Linux 5.13.0-40-generic'
  linux /boot/vmlinuz-5.13.0-40-generic

1>6 menuentry 'Ubuntu, with Linux 5.13.0-40-generic (recovery mode)'
  linux /boot/vmlinuz-5.13.0-40-generic

1>7 menuentry 'Ubuntu, with Linux 4.19.240-rt108'
  linux /boot/vmlinuz-4.19.240-rt108

1>8 menuentry 'Ubuntu, with Linux 4.19.240-rt108 (recovery mode)'
  linux /boot/vmlinuz-4.19.240-rt108

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Bashing-om (bashing-om) said : 		#1

tomdean - Hello

I do not know what command your an to get that output - however the "number" in fact should be a number only - such as 7.

Verify that 7 is the correct menu item:
grep -e "menuentry " -e "submenu" /boot/grub/grub.cfg | sed 's/^[ \t]*//' | cut -d "'" -f1,2 | nl --starting-line-number=0

-hope this helps-

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tomdean (tomdean) said : 		#2

On 5/16/22 15:50, Bashing-om wrote:
> Your question #701812 on Ubuntu changed:
> https://answers.launchpad.net/ubuntu/+question/701812
>
> Status: Open => Answered
>
> Bashing-om proposed the following answer:
> tomdean - Hello
>
> I do not know what command your an to get that output - however the
> "number" in fact should be a number only - such as 7.
>
> Verify that 7 is the correct menu item:
> grep -e "menuentry " -e "submenu" /boot/grub/grub.cfg | sed 's/^[ \t]*//' | cut -d "'" -f1,2 | nl --starting-line-number=0
>
> -hope this helps-
>

I got the syntax from: https://help.ubuntu.com/community/Grub2/Submenus

Using the "1>7" syntax, the system booted into the selected OS.

The 'output' in my email was from typing...

Where does the syntax you describe come from?

Tom Dean

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Launchpad Janitor (janitor) said : 		#3

This question was expired because it remained in the 'Open' state without activity for the last 15 days.