Uninstalling LinuxCNC

Recently I install in my Linux Mint Cinnamon 20.1 desktop theLinux Debian 10 Buster with LinuxCNC version 2.8.2During the installation I thought the LinuxCNC was just another program and I was planning to install it on my 240GB SSD until I realized it was a new OS. The hard disks in my desktop are:/dev/sda  240GB SSD with 2 partitions, Ext4(version 4)/dev/sda1 30GB(Free 15GB), UUID, LinuxBootable Mounted at FileSystem Root/dev/sda2 210GB(Free 155GB),UUID, Linux, Mounted at Home /dev/sdb1 160GB HDD All Free, UUID, Linux File System Ext4(version 1.0)Not Mounted.
/dev/sdc1 79GB HDD, All Free, UUID, Linux, Ext4(version 1.0) Not Mounted/dev/sdc2, 1GB, Extended, Partition2/dev/sdc5, 1GB, UUID, Linux Swap, Swap Version1, Not Active BTW the above 79GB HDD is almost empty except two partitions of 1GB each, so where the LinuxCNC was installed? The install DVD ISO was 2GB and I’m sure the final install was much more.The Linux Mint is installed on the 240 SSD and the LinuxCNC is installed on the 79GB HDD. During the LinuxCNC installation it asked if I want to combine the existing grub menu with the new LinuxCNC grub menu and I said yes (it was the recommended step).I want to uninstall LinuxCNC from the 79GB HDD (which is an old/slow HDD) and install it on the 240GB SSD (the 210GB – Free 155GB) section which is a newer/faster disk. However I don’t know the implication related to the grub boot menu and I want to be careful not to make my desktop unbootable.So how do I uninstall the existing LinuxCNC and re install it from my DVD ISO as per above?Thank you

Do you want to overwrite your current Linux Mint desktop and install the LinuxCNC distribution OS on the 240 GB SSD? If so just install from DVD ISO again and select the SSD this time. All data on the SSD will be lost.

Or do you want to install LinuxCNC to your current desktop OS? If so you'll need to install a realtime kernel and the LinuxCNC package(s) using the package manager. This should be possible but I'm not clear on the details on Linux Mint - others can help if this is what you want to do, I'm sure.

Or do you want to re-partition your 240 GB SSD to make room for a separate LinuxCNC distribution install to coexist with your current Linux Mint desktop install on the SSD choosing at boot (using grub) which one to boot?

I want to re-partition the 240GB SSD and make room for the LinuxCNC to coexist with my LM desktop (there is lots of free space on this SSD).

That’s what I selected in my first attempt to install LinuxCNC but the message/options I got was not clear and decided to install LinuxCNC on the 79GB HDD.

Perhaps it may be better to re partition the 240GB SSD from inside Linux Mint, name this partition “LinuxCNC” is I can and then re install LinuxCNC on the new partition. If I do this what is a reasonable amount of disk space LinuxCNC would need?

However I’m cautious about damaging the grub boot menu which I understand LinuxCNC is part of it now so how do I uninstall LinuxCNC without corrupting the existing grub menu?

Thank you

I would boot a LiveCD (for example your LinuxCNC DVD) and do the partition resizing from there using gparted. If the latter is not installed by default, you can install it using the package manager of the running LiveCD (it will be "installed" to a tempdisk in RAM). I think 32 GiB of disk space should be plenty for a LinuxCNC install.

If you have a somewhat modern system grub should be using UUID:s to identify partitions so things should just work if you just remove the HDD containing LinuxCNC. If it doesn't (for example if grub was installed on the boot sector of the removed HDD) then just install LinuxCNC to the new partition on the SSD; the system will be scanned for bootable partitions and the grub configuration will be updated to show your two existing options only.

Worst case you can always manually run grub-install and/or update-grub from any LiveCD to fix a broken boot loader. See e.g. unix.stackexchange.com/questions/465189/...grub-vs-grub-install for more details.

Many thanks for your time,

I have noticed all my disk partitions are UUID, and I think the easiest way will be to remove the disk containing LinuxCNC and take it from there.

Now I know the required size for LinuxCNC (since I have the space I will go with 50GB partition) I should be able to figure out the rest based on the info from your last post.

Today was the day to fix the “mess” in my Linux desktop but it didn’t go well. From the above discussions I read the link “unix.stackexchange.com….” but didnt help me.

What I did before starting the desktop I unplugged the 80GB HDD which contains LinuxCNC and then started the desktop. Then I got the message “error-no such device 3283a276-4585……”, then error-unknown filesystem. Then at the last prompt I typed exit, or quit, or end but it didn’t work and I shut off the desktop. Since I’m new to Linux I didn’t know what to type at the prompt to exit.

Is there a way to type something at the Grub prompt to direct it to start Linux Mint?

I prefer not to have LinuxCNC installed twice because I’m afraid it may lead to more complications.

Thank you

Had another thought…..

What would happen if I start the desktop with Linux Mint, then when LM is loaded I unplug the data cable from the 80GB HDD where LinuxCNC is located, and then in the Terminal I type Update Grub

Would the Update Grub delete the LinuxCNC boot menu since it can’t be found?

If yes what is the proper command to type at the Terminal? Update Grub or something else?

Thanks

Was your default boot option LinuxCNC before you removed the HDD? I.e. was LinuxCNC the system that started if you made no choice at the grub boot menu? If so, the “error-no such device 3283a276-4585...” message is of course expected once you removed the HDD (the default boot system isn't there any more, after all!).

So just choose another boot option at the grub menu, before you get any error messages? Or don't you get the grub boot menu at all anymore? If so, as I mentioned before grub might have been installed onto the boot sector of the removed HDD, and you would have to boot a LiveCD and install grub to your SSD instead.

Thank you arvidb for your time,

Yes the default boot option was LinuxCNC and as far as I know to change the default I have to edit a file which in the past I was no successful for various reason.

However now I have a major problem as my Linux Mint is not working anymore. I was trying to install the LinuxCNC ISO I have on a DVD into my 240GB SSD. I got to the point where I selected the 200GB free space inside this SSD, I selected to create partition, I was told minimum size is 62GB and I went for that, then format this new partition, and then it was asking for something I didn’t understand, I think it was asking the new partition is not bootable, I selected again the 62GB and again it was not accepted and eventually I got lost and aborted the installation.

After a reboot the LinuxCNC was working fine (since I didn’t touched this HDD) but my Linux Mint took forever to boot, eventually I got to a picture I have as my desktop but I wasn’t able to do anything else in there. Basically Linux Mint is gone but I do have 2 Timeshift backups if I can find a way to access them.

Now I asked the Linux Mint forum for help and if/when I get back my Linux Mint I will not bother to relocate the LinuxCNC(will leave it where it is), too much work for my limited knowledge of anything Linux.

Much appreciated