Upgrade Ubuntu 19.04 and 19.10 without a USB Stick

The following install process allows you install Ubuntu 19.04 or 19.10 from one partition to another without needing to write to a USB stick. There are some modifications to support the Dell XPS 15 9560 laptop, but you can skip these if you don’t need them.

Make sure you have another computer available to create a rescue USB stick if you need it. Most of the time you won’t one and you’ll save you some time.

Install grml-rescueboot:

$ sudo apt-get install grml-rescueboot

Download the installer ISO image into the /boot/grml directory:

$ (cd /boot/grml ; sudo curl -O http://releases.ubuntu.com/19.10/ubuntu-19.10-desktop-amd64.iso)

See: https://ubuntu.com/download/desktop

Update the boot menu to include the ISO:

$ sudo update-grub
...
Found Grml ISO image: /boot/grml/ubuntu-19.10-desktop-amd64.iso
...

Make a note of your current partitions. Be very clear which partition
```
$ lsblk 
```
E.g here are the important part from my partition table:
- /dev/nvme0n1p1 ← boot
- /dev/nvme0n1p8 ← current OS root (will leave unchanged and unmounted)
- /dev/nvme0n1p7 ← new OS root (will reformat and install update here)
- /dev/nvme0n1p9 ← home dir
Reboot.
When the Grub menu appears, choose the ISO image and press Enter.
At the menu select Try Ubuntu without installing and press E to edit the options.
Add entries to the linux arguments:
```
linux <existing args> toram nouveau.modeset=0 --- 
```
- toram loads the rescue image to RAM. See: https://askubuntu.com/a/829962/846736
- (Dell XPS 15 9560 only.) nouveau.modeset=0 is a Dell XPS 9560/9570 option. See: https://github.com/rcasero/doc/issues/6
- the --- separates multiboot arguments. See: https://stackoverflow.com/a/11943253/49630
Press F10 to boot with the modified boot script.
Wait for Ubuntu to boot.
Open a terminal with Ctrl-Alt-T.
Unmount the device the ISO was copied to RAM from:
```
sudo umount -l /isodevice 
```
This is needed so we can edit partitions.

See: https://askubuntu.com/a/896945/846736
(Dell XPS 15 9560 only.) Turn bluetooth off in the system menu as it may interfere with wifi. See: https://help.ubuntu.com/stable/ubuntu-help/bluetooth-turn-on-off.html
Start installation by double-clicking the Install Ubuntu 19.10 launcher.
Proceed through the language settings and wireless connections.
(Dell XPS 15 9560 only.) When you get to choosing updates make sure to install third-party software for graphics so you have graphics card support.

See: https://tutorials.ubuntu.com/tutorial/tutorial-install-ubuntu-desktop#4
Once you get to Installation type choose Something else so you can choose the partitioning strategy.
Choose the <new OS root> partition and choose Ext4, format it and a mount point of /.
I also choose my <home dir> partition, choose Ext4 and mount it.
Click Install Now, review the warning and decide whether or not to proceed.
After installation finishes you can click Restart Now.
Select Ubuntu from the Grub menu and press E to edit it. (This is the new OS you just installed.)
(Dell XPS 15 9560 only.) Add an entry to the linux arguments:
```
linux <existing args> nouveau.modeset=0 
```
Press F10 to boot with the modified boot script.
(Dell XPS 15 9560 only.) Fans will probably overheat, so disable NVidia and use Intel. Run NVidea Settings, choose Prime Profiles and select Intel.

See: https://askubuntu.com/a/1053843
(Dell XPS 15 9560 only.) Restart when prompted.
Fin!