I have installed rocky , but cannot found ubuntu in boot menu

Rocky Linux General
1

rocky 8.5 is installed on /dev/sda6 and ubuntu 20.04 on /dev/sda5 . how can i boot in ubuntu ( cannot find ubuntu in boot menu )

2

You have to choose the boot device in bios.
You may have to press del or F8 or F10 or F12 based on ur motherboard model.
I understand your question as you are asking about grub boot loader menu.
Else you can try with Boot-Repair tool found here
https://sourceforge.net/p/boot-repair/home/Home/

3

how do i install boot repair on rocky linux?

4

I’m not sure whether the Rocky installer probes for existing OS when it creates grub.cfg and the BLS entries.

There are questions though:

  • Do you use EFI mode to boot or still the legacy?
  • Are the /dev/sda[56] where the content of /boot is for these OS?

A problem with one, common bootloader is that both distros should maintain it in
agreement, since both will install and remove kernels / entries.

The grub.cfg does include custom.cfg, if such file exists in same directory.
The custom.cfg could have an entry that chainloads the Ubuntu bootloader.
(Never tried with Ubuntu, works ok with Windows’ bootloader.)

If one does use EFI, then EFI has entries for each bootloader and EFI Boot Menu
can be used to select (non-default) bootloader. That way the OS/bootloaders
do not need to know that other OS exists.

5

found the solution by following this article : How to Rescue a Non-booting GRUB 2 on Linux - Linux.com

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