• Dual boot antergos / kubuntu 18.04

    I have 2 hard drives for 2 operating systems and 2 hard drives for data. on sda I have kubuntu 16.04. and on sdb kubuntu 18.04. Grub2 is sda1 as boot manager.
    Now I want kubuntu 16.04. replaced by antergos but have the fear that I no longer my current kubuntu after installing antergos 18.04. can boot. My plan is a gentle transition from Kubuntu to antergos.
    Can someone help me and say what I have to do to make it happen?
    Thank you and best regards

    Ich habe 2 festplatten für 2 betriebssysteme und 2 festplatten für daten. auf sda habe ich kubuntu 16.04. und auf sdb kubuntu 18.04. Grub2 liegt als Bootmanager auf sda1.
    Jetzt möchte ich kubuntu 16.04. durch antergos ersetzen habe aber die Befürchtung, dass ich nach der Installation von antergos nicht mehr mein aktuelles kubuntu 18.04. booten kann. Mein Plan ist ein sanfter Übergang von Kubuntu zu antergos.
    Kann mir jemand helfen und sagen was ich tun muss um das so umzusetzten?
    Vielen Dank und viele Grüße

  • The easiest way is to install Antergos instead of the Kubuntu 16.04, then after install your system will boot into Antergos.

    • Install grub-customizer and during install mount the Kubuntu 18.04 disk with Dolphin.
    • Run grub-customizer and it will use os-prober to search for Kubuntu (if you don’t mount the disk, this proces will take a long time) then Kubuntu will appear and save the settings.

    It’s most likely that only the kubuntu fallback option will boot the system, you can delete the options that don’t work afterward in grub-customizer.

  • @MatthiasWagner
    I also recommend that you keep the Kubuntu 18.04 installer USB stick around in case of any issues.
    Then you have a way to fix Kubuntu booting if something goes really wrong.

    To fix Kubuntu booting, you would boot from the Kubuntu USB installer, chroot to Kubuntu 18.04, and run a couple of terminal commands to recreate grub stuff. More info about that should be available on Ubuntu related pages.

  • @Bryanpwo Hello,

    here is matthias again. I have antergos installed and after the 1st boot I have in addition to antergos various ubuntu entries in the boot manager - unfortunately, none of them works and ubuntu fallback is not available.
    I mounted my hard drive with kubuntu in antergos and then started customizer - did not help either.

    That’s bad for me now. Can you give me some advice on what to do next?

    many Greetings

  • @matthi-wagner you can copy paste the entry from kubuntu’s grub.cfg to antergos grub.cfg for maintanance… then you will be able to boot to kubuntu and reinstall grub from there…

  • @matthi-wagner I’ve not seen this problem, probably because I use a single disk.

    That said I’ve changed the entries of grub.cfg to something like

    menuentry '(multiboot) Ubuntu 18.10 (18.10) (on /dev/sda7)' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'osprober-gnulinux-simple-de8b07d1-c434-48d5-9204-783d1d8e7b25' {
    	insmod part_msdos
    	insmod ext2
    	set root='hd0,msdos7'
    	multiboot /boot/grub/i386-pc/core.img

    hd0 is the first hard disk /dev/sda
    msdos7 is partition 7 on my hard disk

    What this does is tell grub to boot using the grub setup for disk1 partition 7, so in my case it uses the setup generated by Ubuntu.

    You might have better luck with a similar entry.

    Change hd0 and msdos7 to match your installation.

    I would remove the --class os ... bit.

  • @BlaiseD Oooh! I forgot to say this will not work for machines using EFI.
    I’m still in the process of working out how that will work.

  • @matthi-wagner
    I assume you can now boot to Antergos but not Kubuntu, right?

    You could try writing a menuentry below to a new file /boot/grub/custom.cfg of your Antergos install:

    menuentry "Kubuntu 18.04" {
        search --set=root --fs-uuid "UUID"  # the UUID of Kubuntu 18.04 partition
        configfile /boot/grub/grub.cfg      # grub.cfg in Kubuntu 18.04

    You need to correct UUID on the ‘search’ line. You can find the UUID e.g. with command

    lsblk -fm

    Selecting the menuentry above will show the original Kubuntu 18.04 menuentry.

  • @BlaiseD
    Should be something like this:

    menuentry "Ubuntu..." {
        search --set=root --fs-uuid "UUID"   # put the real UUID of 'hd0,msdos7' here!
        chainloader /boot/grub/x86_64-efi/core.efi  # adjust this path too!
  • @manuel yeah I was aware of that, its just that wasn’t working for me!
    Today for reasons I do not understand it does!

    I have written a python script which reads and modifies grub.cfg, I guess there was something wrong in the generated entries that I was unable to spot :-(.
    Anyways the minimal entry that the script generates and works for me is

    menuentry '(multiboot) Ubuntu 18.04.1 LTS (18.04) (on /dev/sda9)' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'osprober-gnulinux-simple-ede1b768-0cce-4497-bb60-dd4534617c4e' {
    	chainloader (hd0,gpt9)/boot/grub/x86_64-efi/core.efi

    This is within the antergos grub.cfg.

    At the moment my python script locates core.img or core.efi in a hacky way, I need time to change it to use grub-mount.
    Also script runs entirely with root privileges, I plan to modify it so that only the requisite work is done with root privileges. Much more safer that way.

    When I’m happier with the state of the script I will put it on github.

    The reason I prefer multiboot or chainloader is that if other distros are updated and the kernel changes and older kernels images are deleted, bouncing from the Antergos grub.cfg to the distro grub.cfg should just work.

  • @BlaiseD
    If you put that menuentry to file /boot/grub/custom.cfg instead of grub.cfg it will not be overwritten by grub-mkconfig.

  • @BlaiseD
    Hello, I have some bad actions behind me. after an antergos update, the system was no longer serviceable - the windows were criss-crossing - impossible to do. i have reinstalled on sda kubuntu 18-04 hoping that i can reboot my old system on sdb but unfortunately it does not start. it is offered in the boot manager but the following error occurs: PKCS # 7 signed not signed with a trusted key. I urgently need my old system and unfortunately I’m not a pro. Can you help me?
    Greeting Matthias

  • @matthi-wagner Oooh, that error is strange (to me at least).
    Can I suggest you try sysrescuecd to see if you can boot kubuntu 18.04 on sdb I’ve used that to recover when things have gone badly wrong.
    (I have sysrescuecd on a usb-stick ready to use at all times.)
    I think it will help establish that kubuntu on sdb is bootable.

boot320 dual40 kubuntu1 18.041 Posts 14Views 224
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