Ubuntu not shown in os-prober

[JoHubb]

I'm struggling after upgrading from 18.04 to 20.04. Now I wish to do a clean install on the existing Ubuntu partition.
Trouble is, I cannot ID the correct partition to overwrite. I run a triple boot system.

OS-prober gives this, but no sign of ubuntu.

I can see from the next command that all is not well! The main thing is to identify the existing Ubuntu partition.

Thanks for some help!

[oshunluvr]

I believe os-prober detects install other than then one you're using, Have you tried booting to Mint and running it there? Although this seems like a very roundabout way to get some basic info.

Is the install you're trying to identify bootable? If yes, boot to it and see what mounts. If the above screenshot is from your *buntu install, it's installed to sde2. Looks like Windows is on sdf4 and mint is on sdb2. Your windows bootloader or it's own efi folder must be on sdf2.

If you're going to keep this number of partitions (like me) you might considered using labels when you install a file system so you can read them with a simple lsblk or maybe have an organization plan you stick to. I do both of these - all partitions are in a specific order: boot or efi, swap, install, other. Then all but BIOS_BOOT partitions are labeled. Here's my lsblk:

[FONT=monospace][COLOR=#54FF54][B]stuart@office[/B][/COLOR][COLOR=#000000]:[/COLOR][COLOR=#54FFFF][B]/subvol[/B][/COLOR][COLOR=#000000]$ lsblk[/COLOR]
NAME      FSTYPE LABEL       UUID                                 FSAVAIL FSUSE% MOUNTPOINT
nvme0n1                                                                           
nvme0n1p1                                                                         
nvme0n1p2 swap               91fe81e2-89a3-453d-9341-3d4a3bd61f66                [SWAP]
nvme0n1p3 btrfs  970Pro      60834933-1e99-4d5c-922c-9abbc373e172    118G    74% /subvol
sda                                                                               
sda1                                                                              
sda2      swap               96e0e474-bd09-4389-b481-6b3dc409f913                 
sda3      ext4   vm_drive2   2d982ea9-abdb-4846-9802-36b721ab5556   49.5G    77% /mnt/vm_drive2
sdb                                                                               
sdb1                                                                              
sdb2      swap               77052132-aa1d-4f53-94a9-ef5d93e1c9c1                 
sdb3      ext4   vm_drive1   155c45ce-3f39-4094-9be7-fab95d5e0df9   63.5G    71% /mnt/vm_drive1
sdc                                                                               
sdc1                                                                              
sdc2      btrfs  storage     34f7d49b-ebf1-4d06-a899-2de14ee92b5d                 
sdd                                                                               
sdd1                                                                              
sdd2      btrfs  root_backup 77de9ade-e3ad-42fb-a400-84493de9827f  452.5G    51% /mnt/root_backup
sdd3      ext4   vm_backup   38c1cdd4-7ca3-4e34-81e1-4a04f6b6ae78    621G    32% /mnt/vm_backup
sr0                                                    
[/FONT]

My setup is somewhat different because all my linux installs reside on the same partition. I use BTRFS so all (currently 8) are on the 970Pro partition. I don't have Windows on this machine.

If you want some fun, mount ALL the partitions under /mnt then try this from the /mnt folder:

find . -maxdepth 3 -type f -name lsb-release -print 2>/dev/null -exec tail -n +1 {} +

[oshunluvr]

Also it occurs to my that your grub config should have the partition info in it if it's bootable right now..

[JoHubb]

Thanks! This is a good help.

os-prober when run in Mint confirmed that Ubuntu is on sde2. I wish I knew how you were able to see that in my lsblk.

Ubuntu does boot, but it's wonky - it does crazy things. For example, I made a terminal screenshot of os-prober for this thread. Now, I find a link to this screenshot on the desktop. It does this with every application I use, Dolphin, websites, etc. It creates an un-commanded desktop link for just about everything, even documents. Other functions aren't right too and it freezes regularly. It's no use in this state. I should have done a clean install at the beginning.

In grub.cfg Ubuntu is reported but its partition is not given. The partition details are there for Mint and WIndows and confirms your info.

I'm usually up for fun! Maybe after I get 20.04 running I will try your /mnt idea.

Best wishes!

[oshunluvr]

... I wish I knew how you were able to see that in my lsblk...

Because your lsblk output included:

[FONT=monospace][COLOR=#000000]└─sde2   8:66    0   931G 0 part /[/COLOR]
[/FONT]

That slash at the end means "mounted as root folder". So assuming you had booted from Ubuntu, that's where it installed.

grub.cfg by default contains UUIDs and you can match those to a partition. My "lsblk" output is generated by this command:

sudo lsblk -o name,mountpoint,label,size,uuid

so it shows UUIDs but blkid will also. For that I use:

sudo blkid -c /dev/null -o list

so it's more readable. Both the above commands are inserted in my bash_aliases file so I can run them with a single word:

~~~
[COLOR=#000000][FONT=monospace]alias blkid='sudo blkid -c /dev/null -o list'[/FONT][/COLOR]
[FONT=monospace]alias lsblk='sudo lsblk -o name,mountpoint,label,size,uuid'
[/FONT]~~~

[claydoh]

os-prober when run in Mint confirmed that Ubuntu is on sde2. I wish I knew how you were able to see that in my lsblk.

From your image, sde2 is marked as being mounted as '/' which is the root of the currently running OS.

[JoHubb]

Because your lsblk output included:

[FONT=monospace][COLOR=#000000]└─sde2   8:66    0   931G 0 part /[/COLOR]
[/FONT]

That slash at the end means "mounted as root folder". So assuming you had booted from Ubuntu, that's where it installed.

grub.cfg by default contains UUIDs and you can match those to a partition. My "lsblk" output is generated by this command:

sudo lsblk -o name,mountpoint,label,size,uuid

so it shows UUIDs but blkid will also. For that I use:

sudo blkid -c /dev/null -o list

so it's more readable. Both the above commands are inserted in my bash_aliases file so I can run them with a single word:

~~~
[COLOR=#000000][FONT=monospace]alias blkid='sudo blkid -c /dev/null -o list'[/FONT][/COLOR]
[FONT=monospace]alias lsblk='sudo lsblk -o name,mountpoint,label,size,uuid'
[/FONT]~~~

Of course / ,I knew this but I did not realise / shifted around depending on the OS selected from the grub menu.

I thought in my ignorance, that there was a boot file somewhere which served all the OS's. Always learning.

The bash_alias commands would be useful too. Maybe it's a bit too soon for me to start writing commands in bash_alias! When I get 20.04 cleanly installed I will feel freer to start enjoying myself.

[JoHubb]

In #4 I referred to 'wonky' behaviour. Before doing a clean install of 20.04 over the upgrade version, I decided to update my UEFI BIOS. There had been three or four updates since the original in 2015.

Since flashing the latest BIOS it seems that the Kubuntu upgrade install is working properly, if a bit slow at times.

So, in the meantime, I am holding off doing a clean install as planned.

Thanks again. oshunluvr, for interest and advice.