Use existing grub with new Ubuntu 16.04 install

A curiosity question:

I have an existing 14.04 installation, with a customized grub (font sizes, background image - nothing really significant). I have spare space on the boot drive on which I want to install 16.04 for testing.

My question is: will a new install just modify the existing grub (i.e. add 16.04 to the existing list of choices) or will it just overwrite everything and incorporate the existing 14.04 into its own list?

Not a show stopper by any means, but I haven't found anything that explains what all is going on with the boot (well, there is lots of info on the web, but so many conflicts in the undated answers that it's hard to ferret out what's current). I assume that each OS keeps its own version of its ramfs, but also assume that the boot loader is "universal" (I no longer have any Windows partition).

Thanks for any enlightenment ...

I don't know how experienced you are, but you could install with the mini CD, I choose 'Expert Mode', they may have deprecated the 'continue without installing bootloader' option (you can always cancel out of the install if in doubt), they are forever doing silly things to take control away from the user. I 'hand installed' my Ubuntu Xfce 14.04.x on my sdb SSD, that way you have more control over what 'spyware' you can remove post install (in a typical install, removing such packages will drag out many 'dependencies', because a hand install marks packages as 'manually installed', it makes them easier to surgically remove), like 'scope' for example, I was able to totally clean it up from Ubuntu's proprietary 'snoopware'. Then afterwards, go in to your 14.04 install and run "update-grub" as root, it should 'find' your new 16.04 install and point to it in the boot options.

FYI, 14.04.x uses the upstart init system with traces of systemd creep, 16.04 is a full-blown systemd implementation. I found 16.04 to be an ugly and buggy systemd mess, but that's just me, YMMV.

It's been a while since I installed any *buntus but IIRC, if you install 16.04 using the defaults, it will overwrite your current grub. Again, IIRC at some point during the installation when it comes to installing the bootloader you have to go into Advanced mode and then you can select where grub will be installed. You want grub installed on the same partition where you're installing 16.04, i.e. sda* where the "*" is the partition number for your 16.04 installation. By default, the install routine will install grub to "sda" which is shorthand for the mbr of sda, thus overwriting your current 14.04 grub.
After the 16.04 installation is complete, reboot and you will see your old 14.04 grub boot selection screen(if not, you overwrote your 14.04 grub) but there will not be an option to select your new 16.04 installation yet. Boot into 14.04 and then update grub by running:

sudo update-grub

Grub will then pick-up your new 16.04 installation and create a boot entry for it which will be visible next time you reboot.

Originally Posted by kilgoretrout You want grub installed on the same partition where you're installing 16.04

I forgot about that, it is another option to what I already said, but thanks for clarifying.

Thanks much for the quick reply. I wasn't aware that such a thing (the mini CD) existed, and I just downloaded it to take a look. It sounds like that might be just what I'm looking for. As for experience, definitions of that vary wildly, so I don't know; I did my first software modification on a Univac 1004 back in the late 1960s, so I've fiddled with this stuff (countless OSs over the years) for a while, but things keep changing so often (not necessarily improving - just changing) that I'm not often sure what I'm looking at.

You are certainly not the only person with negative opinions about 16.04, which is why I want to try it in such a way that it is still removable with ease. Of course, I'm also one of apparently only a very few who like the Unity interface (I value vertical space more than horizontal for what I do), so I'm likely not in the center of the bell curve anyway.

I can't do anything with all this until the weekend, but I look forward to giving it a shot.

Oh, one more thing, you will need a configurable internet connection to use the mini CD (don't let the name fool you, you can copy it to a bootable USB stick or burn it to DVD/BD), I am currently on 'free wifi' where I am (I'm used to a blazing fast wired cable internet connection, lol) and had no problem using the mini CD (configuring the wifi), it was a bit slow but tolerable. It will first download necessary installer components (most defaults, like the kernel choice for example, are pre-highlighted, you'll just be hitting Enter alot), then after the 'base system' is installed, it will ask you what features/GUI you want, that can be a 1000+ package download (ranging from lite to bloated), easily, it's interesting to watch. Best of luck.

Options are to test using a DVD or flash drive or using a virtual machine. If you want to install to a hard drive, definitely use the manual installation type which is referred to as "Something Else" in Ubuntu. If you use another option, it's basically an auto-install which gives you no control. With the manual option, you will be able to select to install to the root filesystem partition as suggested above. You need to watch for the "Device for bootloader installation" option. You would then reboot to 14.04 and run sudo update-grub which should pick up the 16.04 install.

If you accept the defaults, Grub will install to the MBR from 16.04 and if everything works properly, should include an entry for 14.04 in the boot menu. This option is simpler but the first option is less risky simply due to the fact that if there is a problem with the 16.04 install, you won't be able to boot either.

You haven't indicated whether you are using UEFI and this post will only work if you are not.

Is it just me or are people repeating what's already been said? Why didn't you other people answer before I did if you wanted to help so much? You're saying what's already been said, just worded differently. *eye-roll*

If you read CVAlkan's reply, you would have noticed CVAlkan has DECADES of experience with installing operating systems, CVAlkan also stated he/she is going to try the mini install CD, not the hand-holding typical Ubuntu installer abomination. Which begs the question, why did you chime in after all that? To make yourself feel like your helping, or smarter than other people? Give me a break. I'm so sick of elitism.

Edit: In the future, click on Zero Reply Threads like I do instead of trolling ANSWERED threads at the top of sections lists.