I did not know that. You are talking about shuffling the order in the grub menu, so a particular linux boots by default?
Usually the one that controls grub gets to the head of the menu. I have always left it at that.
1 Like
Thanks so much, You´re really great. 
I looked up the topic of OS-PROBER in the meantime and also found it here: OS Prober is Disabled in Ubuntu 22.04, Here's a Workaround - OMG! Ubuntu
The
OS_proberfeature is disabled by default in GRUB 2.06, which is the version included in Ubuntu 22.04. […]
So, for the moment, Ubuntu 22.04 (or more accurately GRUB in Ubuntu 22.04) does not detect any other operating system during or after install.
I didn´t know that. (L)ubuntu 20.04 still uses grub 2.04
That said your method looks great. 
Just two things there:
I don´t have a separate swap partition but use a swapfile. So I guess I may neglect that point.
With “tell it to install grub” I guess you mean “Device for bootloader installation”, right?
That´s for the new OS. Would I have to do the following in the old OS then?
OS-PROBER-DISABLE=true
If so I´d have to insert the line as my current Lubuntu 20.04 (with grub 2.04) doesn´t have that line already (see comment above).
Thanks so much. You´re too kind.
That would answer my question I just asked Neville. Thanks a lot.
Many greetings
Rosika
Not even remotely a pro, Rosika, although I thank you for the compliment. Just a very old retiree with available time. To the point, I just installed the Mint 21 beta alongside Mint 20.3 and Rolling Rhino ( a Ubuntu spin of 22.04) ON THE SAME HARD DRIVE. I let the installers create the partitioning, and each time, Grub picked up the new distro into its menu. In fact, it also picked up Ubuntu MATE 22.04 on the second HDD in my machine. Each menu title needs to be edited (they all say ‘Ubuntu’ or ‘Mint’) but I can tell them apart by their order.
Yes, I choose the wrong one sometimes. I told you I’m old. But not as old as Neville, who really is a pro.
This forum would be deadly dull without you, Rosika.
1 Like
Hi Bill, 
You´re very welcome.
Still, compared to me, all of you in this thread (and many other threads as well) are real pros…
… and I´m not ashamed to say so. 
That way I can learn so much. You all are great indeed.
Yes, I can confirm that scenario, Bill.
My Lenovo H520e has still WIN 8.1 on the internal disk (although I don´t make much use of it any more).
My Lubuntu 20.04 LTS is installed on an external 1 TB WD Elements 25A2 drive. I put the bootloader there during the installation process.
Grub still shows WIN as an option, although it is - like in your case - an OS on another drive.
What a beautiful compliment. Thank you very much, Bill.
… although I´m convinced my input may be considered pretty limited as far as knowledge and quality is concerned…
Thanks a lot and many greetings from Rosika
1 Like
@nevj
It is not really a shuffling, but a choosing of which OS one wishes to be default. After one runs the grub-update in the new Linux install, one will reboot into the grub menu. Grub, as you know, will have several entry’s, the first entry will be 0, which is usually the default, one then counts from 0 down to the
entry one wishes to be default. You then boot back into Linux and, I use nano, and run nano /etc/default/grub and enter the entry # in the GRUB_DEFAULT=#, and on the next reboot that entry will
be highlighted. I sometimes will use my Windows install as the default OS to boot.
Now the GRUB_DISABLE_OS_PROBER=true, will have to be enabled, so Linux can find other Grub entry’s.
I was in Windows and I need to add this to the data!!!
GRUB_DEFAULT=saved can also be used but the GRUB_SAVEDEFAULT=true has to be entered for this to work.
2 Likes
Well, when I first changed over to a Linux distro in mid 2016 I wanted to leave WIN where it was for the time being.
So I installed Lubuntu on a USB-stick .
There was an article in Easy Linux magazine at the time (2/2016) with the title “Linux am Stiel”, i.e. “Linux on a stick” (in German though), which was quite intriguing. So I followed that path.
Later on it became clear I needed more space for personal data and VMs. Accordingly I installed Lubuntu on the external HDD.
In the meantime I made use of the internal HDD for dumping an ever-increasing collection of ISOs.
It´s pretty full now .
1 Like
@Rosika
Move the data to the external drive and shrink the W8.1 drive for Lubuntu. I would think Linux would run better from the internal drive than from any usb drive.
1 Like
Hi Daniel,
I could do that … in theory.
But the internal HDD is just 500 GB in size and had already been pretty “full” before (just by WIN and what´s installed there)
I guess just by moving the ISOs I wouldn´t gain all too much space.
Hmm. o.k.
Of course that may very well be true.
However I really cannot say that I ever have noticed any lag or some such thing with Lubuntu running from my external HDD.
In spite of the fact it´s using USB 2.0.
Nevertheless your suggestion is certainly worth considering.
I would have to dump the ISOs somewhere else then, as I don´t want them to reside on my external HDD.
When doing my monthly clonezilla disk-backup I wouldn´t want them to be part of the ever-repeating backup routine…
Thanks anyway for your help.
Many greetings
Rosika
@Rosika
ISO’s can consume quite of bit of space, I see no real advantage in saving an ISO, except for the one you may be using.
500GB, how much space do you need for Linux, and if you no longer use W8.1, then boot your PC with Gparted and get rid of W8.1, I see no real advantage of keeping W8.1.
1 Like
It depends on the situation. If your internet connection is very slow and limited due to having only a few GB of download material permitted each month, it might make sense to save the ISOs. If the internet connection is such a big bottle neck, it makes sense to a degree to save all that stuff onto cheap storage media.
1 Like
@Akito
Like I said, keep the one you are using, within the confines, of the OS you are using. The other
ISO’s are just their and using space and in need of being edited due to age.
Yes. What else is a HDD needed for? If you keep the HDD empty, you might as well sell or gift it… 
1 Like
Like what?
… …
…
Right, sorry my terminology confused you
That´s for the new OS. Would I have to do the following in the old OS then? OS-PROBER-DISABLE=true If so I´d have to insert the line as my current Lubuntu 20.04 (with grub 2.04) doesn´t have that line already (see comment above).
First note my correction, which I added to an earlier reply. I guessed
the name wrong, it should be
add GRUB_DISABLE_OS_PROBER=false to /etc/default/grub
Now, as you noticed, there is usually no GRUB_DISABLE_OS_PROBER statement in /etc/default/grub. Therefore it is disabled by default.
Yes you add
GRUB_DISABLE_OS_PROBER=false`
to /etd/default/grub
in the new linux (assuming it controls grub)
So yes you have to insert a line.
Note that it is a confusing double negative! To enable it you have to set disable to false.
What you do in the old linux seems debatable, if you are going to use the new linux to control grub. I think it doesnt matter, Daniel thinks you need to set it to true.
And , of course, if you are going to leave the old linux in control of grub, then you have to edit its /etc/default/grub. It is the linux which controls grub that is in charge of probing for other OS’s
os-prober is just a program. You can run it, without grub , just by typing os-prober as a command. Its quite safe. It will just list all the OS’s it can find on other partitions. What you are setting in /etc/default/grub is whether grub uses os-prober. It only neees to use it if there is more than one OS.
Another thing that happened to me once, is that os-prober is not installed. The fix is simple… you just install it. I think it will be there in Ubuntu.
Regards
Neville
1 Like
Thanks, I get it now. That is useful.
Hi all.
I hope you´re all well … and thanks for your latest comments
Right, that might be one solution. Thanks for the suggestion.
Thatt´s exactly the case with me. Thanks, Akito for remembering my situation.
With my 5 GB data allowance per 28 days I´ll have to take into account such details.
BTW:
When doing a fresh install next April I´ll have to switch over to another data plan (one time only in 2 years, I hope )
I would need “Datenpaket L” then as I get 10 GB instaed of 5 GB (https://media.medion.com/cms/medion/alditalkde/ALDI-TALK-Preisliste.pdf?dl=0722 ).
… cos´ Lubuntu´s ISO download has increased to 2.4 - 2.5 GB for the first time 
Last time ( for focal) it was 1.6 - 1.7 GB …
Don´t worry, that´s alright. I think I got it.
O.K. then.
I add to the new system:
Then:
I think setting the old OS to
GRUB_DISABLE_OS_PROBER=true
surely cannot hurt.
Well, I think I´d want the new system to be in control of grub.
Thanks for the hint. I also found a discussion on the topic here: [SOLVED] GRUB_DISABLE_OS_PROBER=true
Still I´m not quite sure in which situation exactly to apply this command… 
If I run the command … does it take care of editing /etd/default/grub; so is it a one-time-only command or would I have to issue the command every time in a new session 
Yes, my present Lubuntu has it installed by default.
Thanks so much to all of you…
Many greetings from Rosika
No sorry I confused you again
If you run os-prober at the command line , all it does is list things on the screen. It does not setup grub, so it is quite safe to do that anytime.
When grub calls os-prober, it is another matter. Then grub takes the output from os-prober and uses it to construct the grub configuration.
This is how grub ensures that all the linux partitions that you have end up in the grub menu
The entry in /etc/default/grub is just there to tell grub to use os-prober, or not to use it… If you only have one linux partition, grub does not need to call os-prober… that is why it is disabled by default.
If you have more than one linux partition, you need to enable grub’s use of os-prober, otherwise grub will only find the one linux that controls grub.
Sorry for the longwinded explanation. It is my mess and I had to fix it
Regards
Neville
1 Like
No, thats OK, and @4dandl4 thinks it might help.
I think your choice of letting the new linux control grub is the right one
1 Like