Save your data...
Well that’s what I’m trying to do - I installed a new copy of Mint and was copying from the old partition to the new partition, ran out of space,
How does “single image mode” show up in Grub?
BTW, I’ve been using Linux RHEL 8,1 for my work computer so I’m not a Linux newbie,
RHEL8 single user mode instructions at this link.
https://lintut.com/how-to-boot-into-single-user-mode-in-centos-rhel-8/
Probably too late for the easy fix which is to search the web for an answer; https://duckduckgo.com/?q=lost+password+ubuntu&ia=web
Something like this: Reset Your Forgotten Ubuntu Password in 2 Minutes or Less
https://www.howtogeek.com/howto/linux/reset-your-forgotten-ubuntu-password-in-2-minutes-or-less/
So if you’re already into resizing/reformatting ...
Anything sensitive is not in your Home folder. It’s in System files.
Your data = your Home folder. That’s all you need to save and even then, you can go through and ignore stuff you really don’t need. Make sure when you save/backup your Home folder that you View hidden files in whatever file manager you’re using. Those hidden files are settings and configuration for all your programs. If you save those and restore them on the new install, everything comes back like nothing ever happened, even your open browser tabs.
That’s why the ideal thing is to create a separate partition for /Home when installing Linux. Then you can re-install at any time and reuse /home but NOT format it.
This time, just boot up with a Live CD/USB, and backup /home to a second USB stick or external hard drive and make sure you get the hidden files. That is anything that starts with a dot/period. They’re not visible by default in the file manager but there should be an option in the menu to view them.
Then reinstall with a separate partition for /home which needs to be pretty big, at least for me. I have a lot of files, including full backups for a few websites. I do about twice the size of the root / partition. With my system, I have 120gb for /home and 60gb for install or system files aka /
You might be able to do 50/50 or even smaller for /home than / aka root/system. Depends.
Use the same partition for the /boot as the / aka system files.
In my case, I have a dual boot with Win7 so when I installed Kubuntu, it had sda1 and sda2 already with sda1 being Windows’ system restore partition and sda2 being Windows.
Since I have two hard drives, sda3 is on that same hard drive and became Kubuntu / and /boot. sdb1 was the second hard drive and became /home.
Been running various flavors of Ubuntu for going on 20 years and this was the first time I made a separate partition for /home. Now I don’t have to worry about backing up 100gb(103.4gb currently) of /home files and restoring them, as long as I don’t format /home when/if I need to reinstall. That’s half a day’s work of copying files and another half a day copying them back.
My full install of Kubuntu 20.04 with plenty of programs totals less then 40gb as opposed to my Home folder of 104.3gb. ymmv