Moving home partition... then update-grub from separate partition?

[chconnor]

Hi -- getting ready to go from 15.04 to 16.04. I want to enlarge my root partition first. Here is where the partitions on my main SSD stand:



...I want to slide sda3 (/home) to the right into the unallocated space, and then enlarge sda2 (/), to use all of that space.

AFAIK I can't resize/move a partition while booted on it, so I need to do this from a separate boot, which is fine -- I have a separate dedicated utility partition I can boot to.

I'm just worried about grub after I've done the operation: since I'm not changing the start of /, but I am moving /home, do I need to update grub before booting?

My instinct says no, but if so, what's the easiest way to update grub from my separate utility boot partition? There are a few bootable partitions on /sdd, besides windows on /sda1 and linux on /sda2; I just want to make sure I can at least get back to my regular linux boot to run a clean update-grub...

I find this: http://askubuntu.com/questions/14524...-from-a-livecd

...the main answer suggests booting from the utility partition, mounting the main linux partition, mount --bind'ing a few system directories over the linux partition directories, chrooting to the mounted partition, and then running update-grub. Is that still the best way? (It's a four year old answer.)

Thanks!

[Qqmike]

do I need to update grub before booting?
My instinct says no, but if so

Gee, I don't think you'll need to run update-grub or re-install GRUB. I can't think of why anything grub-related would be in your personal /home; think it is all in / root system directories, like /boot/grub, etc/default/grub, and so on.

OK, but if you do ever have to re-install GRUB and update the configuration files, then yes, that chroot method is the gold standard. The link you gave should be good. Another popular way is by using the utility Boot-Repair:
https://help.ubuntu.com/community/Boot-Repair
-- very handy, and usually works fine. Boot-Repair will try to detect the setup you have and then will re-install GRUB and do the GRUB updating needed, and will even generate a report you can access on a linked location.

[chconnor]

Thanks! Yeah, I just didn't know if grub cared that the root partition would be resized, or if it cared that /home would be moved. But makes sense that it wouldn't. I will forge ahead.

I've also used boot-repair in the past and appreciated it very much. :-)

[chconnor]

All went without a hitch. It's so nice when things just work. :-)

[Qqmike]

Ah, good! Glad it went well, glad it went "as expected."